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Nivgasnv LIBRAmES

 

 

 

Liam.“ WWWW WWWQLELWWWWWWW W W W
Michigan State 3
University

 

 

This is to certify that the

dissertation entitled

ULTRAFILTRATION IN SOFT WHITE "DOMIATI" CHEESE MANUFACTURE

presented by

ENAYAT AHMED GOMAA

has been accepted towards fulfillment
of the requirements for

Ph.D. degree in Food Science

 

M Maw

Major professor

 

Date 1/207 I970

 

MS U is an Affirmative Action/Equal Opportunity Institution 0- 12771

 

 

PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before one due.

 

 

1 DATE DUE ” DATE DUE DATE DUE H

 

 

 

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W03” Em—

 

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as v 7 I974

 

SW

 

 

 

3;“ 0? Hf}

 

 

 

 

 

 

 

 

 

 

MSU Is An Affirmative ActlorVEquel Opportunity Institution

 

 

in

 

WIWTION IN SOFT WHITE 'DORIATI"
CHEESE MANUFACTURE

BY

Bnayat Aimed Gonaa

A DISSERTATION

Submitted to
Richigan State University
in partial mltillnent of the requirements
for the degree
of

DOCTOR OF PHILOSOPHY

Department of Food Science and Hanan Nutrition

1990

(:1!
.JC’

oosq

ABSTRACT

ULTREIILTRATION IN SOFT WHITE "DOHIATI"

CHEESE EINUEACTURE

E!

ENRYAT AHMED SONAR

The effects of pilot plant scale ultrafiltration (UF)
on the retention of milk and whey components were studied.
Also, the technical feasibility of ultrafiltration in the
manufacture of white soft "Domiati" cheese was studied.

Retentate produced by diafiltration was lower in
lactose and ash and higher in protein contents than
retentate produced by ultrafiltration. Electrophoretic
patterns of protein revealed substantial increase in its a-
lactalbumin and fi-lactoglobulin. Fat and minerals associated
with protein were quantitatively retained in the retentate.

Soft white Domiati cheese was made from whole milk and
its ultra/diafiltrated retentate using the Maubois, Mocquot,
and vassal ( MMV ) and/or conventional technique. Chemical
analysis confirmed the retention of more whey proteins in
UF-cheese than in conventional cheese. Higher
concentrations of free amino acids and free fatty acids were
also observed in UF-cheese. Sensory evaluation of the

flavor, body/ texture and color revealed that UF-cheese was

timer and
When
pouches to
solids con
observed.
resolution
In am
reconstitui
methods: (a
under vacui
7°C for eig
content the
The liberat
significant

for pouch C

 

firmer and better liked than conventional cheese.

When UF- and conventional cheeses were ripened in
pouches for three months at 10°C, a significant increase in
solids content, free amino acids and free fatty acids was
observed. Texture profile analysis and electrophoretic
resolution indicated differences between the two cheeses.

In another experiment retentate was freeze-dried, then
reconstituted for making cheese. Cheese was ripened by two
methods: (a) in polyethylene-lined aluminum pouches sealed
under vacuum, and (b) in 8 % brine in plastic containers at
7WC for eight weeks. Pouch-ripened cheese had higher solids
content than cheese ripened in brine solution at p< 0.05.
The liberation of free fatty acids and free amino acids was
significantly increased for both cheeses with greater values
for pouch cheese than for brine cheese. The new method of
vacuum pouch ripening resulted in improved cheese yields
and an acceleration of cheese ripening.

A process for incorporating whey protein concentrate
(WPC) into milk to observe its effect on Domiati cheese
yield and quality was investigated. Milk was supplemented
with WPC on protein basis up to 1:1. Increasing the
proportion of WPC resulted in cheese with increasing content
of total solids, protein, lactose and decreasing content of
fat and coagul- ation time. Maximum cheese yield was
obtained with milk mixtures of 1:0.75 protein ratio.
Hardness, chewiness and gumminess were significantly high in

unsupplemented cheese.

DEDICATION

Dedicated to my family
My husband, Dr. Mohamed Abouzied
My daughter, Amy

My son, Sherif

ii

The a
guidance, 5
of this the

Apprec
his guidanc
manuscript.

Sincer
as chairman
doing the b

Gratef
Committee:
Benek, Depa
Department

advice and

 

The au
rewarding i:
eX’cended to

The aul
Egypt who 4'

 

LaSt '
hUSband' HQ
thouslat thi

 

 

 

ACENIILEDGEHENTS
The author wishes to thank Dr. P. Markakis‘ for his
-guidance, support and assistance in reviewing the manuscript
of this thesis and making suggestions for its improvement.

Appreciation and special thanks to Dr. J.R. Brunner for
his guidance, invaluable advice and preparation of the
manuscript.

Sincere appreciation to late Dr. C.M. Stine, who served
as chairman of her Special Committee for the importance of
doing the best job that one can. He was a good friend.

Grateful acknowledgment is due members of the guidance
committee: Drs. L.L.Bieber, Department of Biochemistry, E.S.
Benek, Department of Plant Pathology, J.A. Partridge,
Department of Peod Science and Human Nutrition for their
advice and effort in reading this manuscript.

The author stay at Michigan State University was made
rewarding by many good friends, and grateful appreciation is
extended to Dr. J.I. Gray, Dr. A. Asgher, and S. Rabie.

The author is grateful to the people and Government of
Egypt who supported her during this study.

Finally, to my family for their love, sacrifice and
support.

Last, but not least, I am forever indebted to my
husband, Mohamed, for his love, support, and encouragement

thought this long and difficult process.

iii

LIST 0
LIST OI
INTRODI
REVIEW
Th

APP

TREE! OF CONTENTS

Page
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . vii
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . xiii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . 3

The concept of Ultrafiltration . .
Ultrafiltration Membrane .
Ultrafiltration Configuration
The Mode of Ultrafiltration .
Advantage and Limitation . .

Application of Ultrafiltration in D

Milk . . . . . . .
Soft Cheese . .
Feta Cheese . .
Cottage Cheese .
Cream Cheese . .
Ricotta Cheese .
Other Soft Cheese

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p
O

Retentate-Supplemented Milk for Cheese

Making . . . . . . . . 17
Domiati Cheese made by Ultrafiltration . . . 18
Ultrafiltration of Whey . . . . . . . . . . . 21

MATERIALS AND METHODS . . . . . . . . . . . . . . . . . 24

Preparation of Retentate . . . . . . . . . . . . . 24
Milk . . . . . . . . . . . . . . . . . . . . 24
Whey . . . . . . . . . . . . . . . 24
Ultrafiltration and Diafiltration . . . . 24

Cheese Manufacture from Whole Milk . . . . . . . . 26
Conventional Method . . . . . . . . . . . . . 26
Ultrafiltration Method . . . . . . . . . . . 27
Freeze Dried Retentate . . . . . . . . . . . 27

Cheese from Whey Protein Concentrate Supplemented
Whale Milk 0 O O O O O 0 29

Chemical analysis . . . . . . . . . . . . . . . . 32
pH 0 O O O O O O O O O O O O O O O O I O O I 32
Total Solids . . . . . . . . . . . . . . . . 32

iv

Page

Fat . . . . . . . . . . . . . . . . . . . . . 32
Salt . . . . . . . . . . . . . . . . . . . . 33
Protein . . . . . . . . . . . . . . . . . . . 33
Sample Preparation . . . . . . . . . 33
Discontinuous Polyacrylamide Electrophor es sis 34
Sample Preparation . . . . . . . . . . 34
Electrophoretic and staining Procedure. 35
Gel Densitometry . . . . . . . . . . . . 36
Amino Acids . . . . . . . . . . . . . . . . . 36
Preparation of Cheese Sample . . . . . . 36
Lactose . . . . . . . . . . . . . . . . . . . 37
Minerals . . . . . . . . . . . . . . . . . . 38
Sample preparation . . . . . . . . . . . 38
Free Fatty Acids . . . . . . . . . . . . . . 38
Color . . . . . . . . . . . . . 40
Texture Profile Analysis . . . . . . . . . . 41
Statistical Analysis . . . . . . . . . . . . 42

RESULTS MD DISCUSS ION . O O O O O O O O O O O O O O O 4 3

PART

PART

PART

I. ULTRAFILTRATION PARAMETERS STUDY . . . . . 44

Introduction . . . . . . . . . . . . . . . . 45
Permeation Flux . . . . . . . . . . . . . . . 45
Material Balance . . . . . . . . . . . . . . 50
Retentate Composition . . . . . . . . . . . 52
Permeate Composition . . . . . . . . . . . . 59
Nitrogen Fractions . . . . . . . . . . . . . . 64
Mineral Content . . . . . . . . . . . . . . . 71
Electrophoresis . . . . . . . . . . . . . . . 79

Whole Milk . . . . . . . . . . . . . . . 79

Skim Milk . . . . . . . . . . . . . . . 86

Whey . . . . . . . . . . . . . . . . . 86
Total Amino Acids . . . . . . . . . . . . 88
Fatty Acids Composition . . . . . . . . . . . 90

II. MANUFACTURE OF DOMIATI CHEESE USING
CONVENTIONAL AND ULTRAFILTRATION METHODS . . 93

Introduction . . . . . . . . . . . . . . . . 94
Chemical Composition . . . . . . . . . . 94
Gel Electrophoresis of Protein . . . . . . . 103
Organoleptic Properties . . . . . . . . . . . 105
Color . . . . . . . . . . . . . . 105
Texture Profile Analysis . . . . . . . . . . 108

III. BRINE AND POUCH VACUUM RIPEN OF DOMIATI
CHEESE MADE FROM ULTRAFILTRATED MILK ,., . . 112

IntrOduCt ion 0 O O O O O O O O O O O O O O O 1 1 3
Statistical Analysis . . . . . . . . . . . . 113
Chemical Composition . . . . . . . . . . . . .114

V

P}

CONCLUSIO
FUTURE RE
APPENDIcgg.
1' Elect

Gel E
2 Amino
3 Hinex-
9 Donia.

Fatty Acids . . . . . .
Amino Acids . . .
Organoleptic Properties
Color . . .

Texture Profile Analysis
Whey Content . . . . . .

PART IV. COMPARISON BETWEEN CONVENTIONAL AND
DURING RIPENING

ULTRAFILTRATED DOMIATI CHEESE

IN POUCHES . . . . . . .

Introduction . . . . .
Chemical Composition .
Free Fatty Acids . . .
Free Amino Acids . . .
Electrophoretic Analysis
Cheese Quality . . . .

PART V. DOMIATI CHEESE FROM WHEY
CONCENTRATE-SUPPLEMENTED MILK

Introduction . .
Composition of Milka
Coagulation Time .
Cheese Yields . . .
Cheese Composition
Cheese Quality . .
Color . .

Texture Profile Anal
Electrophoresis . .
Whey content . . .

g

WP

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CONCmS I CNS 0 O O O O O O O O O O O
FUTURE RESEARCH O O O O O O O O O O

APPENDICES . . . . . . . . . . . .
1. Electrophoresis solutions . .
Gel Preparation . . . . . . . .
2. Amino Acid Analysis . . . . . .
3. Mineral analysis . . . . . .
9. Domiati Cheese Score Card. . .

LIST OF REFERENCES . . . . . . . .

vi

eeeeeeeene

PROTEIN

M

ixtures

Page

123
126
129
129
132
138

142

143
143
148
153
155
157

163

164
165
165
169
173
178
180
182
187
188

191
197

198

199
200
202
204
220

235

lo.

11.

12,

130

14.

15,

 

LIST OF TABLES

Table Page

1. Material balances in concentrated whole milk, skim
milk and whey achieved by ultrafiltration and
diafiltration O I O O O O O O O O O O O I O O 0 51

2. Dry matter composition of whole milk,skimmilk and
whey retentate obtained by ultrafiltration or

diafiltration O O O O O O O O O O O O O O O O O 0 55
3. Permeate composition of ultrafiltrated skim milk 63
4. Permeate composition of ultrafiltrated whey . . . 63

5. Change in the nitrogen distribution of whole milk
during ultrafiltration . . . . . . . . . . . . . . 65

6. Change in the nitrogen distribution of whole milk
during diafiltration of whole milk . . . . . . . 67

7. Change of nitrogen distribution in the
ultrafiltration skim milk . . . . . . . . . . . . 69

8. Changes of nitrogen distribution in the
ultrafiltration whey. . . . . . . . . . . . . . . 70

9. Major mineral content of sweet whey, retentate
and permeate using ultrafiltration . . . . . . . . 72

10. Trace mineral composition of sweet whey,
concentrate and permeate using ultrafiltration . . 73

11. Major mineral content of fresh whole milk,
retentate and permeate by diafiltration . . . . . 75

12. Trace mineral composition of whole milk, retentate
and permeate by diafiltration . . . . . . . . . . 76

13. Major mineral content of fresh skim milk,
retentate and permeate by ultrafiltration. . . . . 77

14. Trace mineral composition in fresh skim milk,
retentate and permeate by ultrafiltration . . . . 78

15. Total amino acid contents of sweet whey and whey
protein concentrate . . . . . . . . . . . . . . . 89

vii

Table

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27,

28.

29.

30.

Fret
rate

The
chee
conx

 

Table

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

Free fatty acid composition of whole milk and
retentate O O O O O O I O O I O O O O O O O O O O O

The composition of whole milk and liquid pre-
cheese used for making Domiati cheese by
conventional and ultrafiltration methods . . . . .

The composition of fresh Domiati cheese made by
conventional and ultrafiltrated methods . . . . .

Comparison of protein fractions between fresh
Domiati cheese made by conventional and
ultrafiltrated methods . . .-. . . . . . . . . . .

Free fatty acids of fresh ultrafiltrate-cheese and
conventional Domiati cheese . . . . . . . . . . .

Free amino acids and small peptides of fresh
Domiati cheese made by Diafiltration and
conventional method . . . . . . . . . . . . . .

Organoleptic properties of fresh Domiati cheese
using ultrafiltration and conventional methods . .

Color of fresh Domiati cheese made by
ultrafiltration and conventional methods . . . .

Texture profile analysis of fresh Domiati cheese
made by conventional and ultrafiltration methods .

The composition of ultrafiltrated freeze-dried
whale milk 0 O O O O O O O O O O O O O O O O O O O

The composition of fresh Domiati cheese made from
ultrafiltrated whole milk . . . . . . . . . . . .

Total and free amino acids content of fresh
Domiati cheese made from ultrafiltrated whole
milk 0 O O O O O O O O O O O O O O O O O O O O O 0

Chemical changes of Domiati cheese made from
reconstituted, diafiltrated whole milk and ripened
in pouches for 8 weeks . . . . . . . . . . . . . .

Chemical changes of Domiati cheese made from
reconstituted, diafiltrated whole milk and ripened
in 8% brine solution for 8 weeks . . . . . . . . .

Page

91

95

97

99

100

102

106

107

111

115

115

116

118

119

Ripening index of Domiati cheese ripened in pouches and

in 8% brine solution for 8 weeks . . . . . . . . .

viii

122

32. Quat

33. Free

34. Orga

 

Table Page

31.
32.

33.

34.

35.

36.

37.

38.

39.
40.
41.

42.

Quantitative changes of free fatty acids in
Domiati cheese made from ultra/diafiltrated whole
milk ripened in pouches for 8 weeks . . . . . . . 124

Quantitative changes of free fatty acids in
Domiati cheese made from ultra/diafiltrated whole
milk ripened in 8% brine solution for 8 weeks . . 125

Free amino acid contents of ripened Domiati cheese
made from ultra/diafiltrated whole milk and

ripened in pouches and brine solution after

8 weeks . . . . . . . . . . . . . . . . . . . . . 128

Organoleptic properties of fresh Domiati cheese

made from ultra/diafiltrated whole milk and

ripened in pouches and 8% brine solution for

8 weeks . . . . . . . . . . . . . . . . . . . . . 130

Color profile of Domiati cheese made from

reconstituted freeze dried ultrafiltrated whole

milk and ripened in pouches and 8% brine solution

for 8 weeks . . . . . . . . . . . . . . . . . . . 131

Texture profile changes during the ripening of
Domiati cheese in pouches and 8% brine solution
for 8 weeks . . . . . . . . . . . . . . . . . . . 139

Fat and protein content of serum and brine

obtained from Domiati cheese made from

ultrafiltrated whole milk ripened in pouches and 8

% brine solution for 8 weeks . . . . . . . . . . . 141

Chemical changes of ultrafiltrate-derived and
conventional Domiati cheese ripened for 1 and 3
months in pouches . . . . . . .,. . . . . . . . . 147

Changes in protein fraction during ripening of
conventional and UF-Domiati cheeses in pouches . . 149

Free fatty acids of fresh and ripened UF-Domiati
cheese for three months in pouches . . . . . . . 151

Free fatty acids of fresh and ripened conventional
Domiati cheese for three months in pouches . . . . 152

Free amino acids and small peptides of Domiati cheese

made by ultrafiltration and conventional methods and
ripened for three months in pouches . . . . . . . 154

ix

 

Table

43. Compo
conce

44. Total
suppl
Donia

45. Coaguf
lilk :
prote

46. Coupe
prote
renne

47- Quant
Domia
SUpp]

48- Quant
Donia

SUppj

49s Orga

‘lade
‘flual
4““ Rate
milk

43' Rate

‘11}
4C' Rats
by’.

514. Cha

‘iia
S
B. Che
111‘

Ch.
‘411

Sc‘

SD.
111.

Table

43.

44.

45.

46.

47.

48.

49.

4A.

4B.

4C.

4d.

5A.

SB.

5C.

5D.

Composition of whole milk and whey protein
concentrate used for supplementing the milk . . .

Total solids and protein contents of retentate
supplemented whey mixtures, used for making
mmiati Cheese 0 O O O O O O O O O O O O O O O O

Coagulation time of Domiati cheese made from whole
milk supplemented with different ratios of whey
protein concentrate . . . . . . . . . . . . . . .

Composition of Domiati cheeses made from whey
protein concentrate-supplementing whole milk using
rennet coagulation . . . . . . . . . . . . . . . .

Quantitative changes of total amino acids of
Domiati cheese made from whey protein concentrate-
supplemented whole milk . . . . . . . . . . . . .

Quantitative changes of free fatty acids of fresh
Domiati cheese made from whey protein concentrate-
supplemented whole milk . . . . . . . . . . . . .

Organoleptic properties of fresh Domiati cheese
made from whey protein concentrate-supplemented
whale milk I O O O O O O O O O O O O O O O O O 0

Rate and volume of permeate derived from whole
milk by diafiltration process . . . . . . .

Rate and volume of permeate derived from whole
milk by ultrafiltration . . . . . . . . . . .

Rate and volume of permeate derived from Skim milk
by ultrafiltration . . . . . . . . . . . . . . . .

Rate and volume of permeate derived from whey
by ultrafiltration . . . . . . . . . . . . . . . .

Change in retentate composition during
diafiltration of whole milk . . . . . . . . . . .

Change in retentate composition during
ultrafiltration of whole milk . . . . . . . . . .

Change in retentate composition during
ultrafiltration of skim milk . . . . . . . . .

Changes in retentate composition during
ultrafiltration of whey . . . . . . . . . . . . .

Page

166

167

168

172

176

177

179

205

206

207

208

209

210

211

212

Table

6A.
GB.
7A.

8A.

88.
8C.

10A.

108.

10C.

10D

102.

101?,

11A.

113

Chanfi
ultra

Chang
diaf:

Percr
fatt}

Peak
milk.
proce

Peaks
durir

Peak
ultra

Compe
chees
for s

Nitrc
recor
Poucr

Table Page

6A.

6B.

7A.

8A.

8B.

8C.

10A.

103.

10C.

10D.

10E.

10F.

11A.

11B.

Changes in permeate composition during
ultrafiltration of whole milk . . . . . . . . . . 213

Changes in permeate composition during
diafiltration of whole milk . . . . . . . . . . . 214

Percent recovery and response factor of individual
fatty ac ids O O O O O O O O I O O O O O O O O O O 2 1 5

Peak areas and relative distribution in whole
milk, casein and TAN during ultrafiltration
process 0 O O O O O O O O O O O O O O O O O O O O 2 1?

Peaks area and their distribution in skim milk
during ultrafiltration . . . . . . . . . . . . . . 218

Peak areas and their distribution in whey during
ultrafiltration process . . . . . . . . . . . . . 219

Comparison of compositional changes of Domiati
cheese ripened in pouches and in 8% brine solution
for 8 weeks 0 O O O O O O O O O O O O O O O O O O 2 2 1

Nitrogen fractions of Domiati cheese made from
reconstituted ultrafiltrated whole milk ripened in
pouches and 8% brine solution for 8 weeks. . . . . 222

Texture profile analysis of Domiati cheese made
from reconstituted ultrafiltrated whole milk and
ripened in pouches for 8 weeks . . . . . . . . . . 223

Texture profile analysis of Domiati cheese made
from reconstituted ultrafiltrated whole milk and
ripened in brine solution for 8 weeks . . . . . . 224

Components of whey of Domiati cheese made from
ultrafiltrated whole milk ripened in pouches and 8
% brine solution for 8 weeks . . . . . . . . . . . 225

Calculated true loss of protein and fat from
Domiati cheese during ripening in pouches and
brine solution . . . . . . . . . . . . . . . . . 226

Ripening index of fresh and ripened conventional
and ultrafiltrated Domiati cheese for three months
in poucnes O O O O O O O O O O O O O O O O O O O O 2 2 7

Texture profile analysis of fresh ultrafiltrated and
conventional Domiati cheese . . . . . . . . . . . 228

xi

Table

11C. C0101
ultra
three

12A. Yield
made
whole

128. Prote
prote

12C. Color
whey
whole

120. Textu
whey
whole

lZE. Compo
whey
whole

 

 

 

Table

11C.

12A.

12B.

12C.

12D.

12E.

Color changes of fresh conventional and
ultrafiltrated Domiati cheese and ripened for
three months in pouches . . . . . . . . . . . .

Yields and yield efficiencies of Domiati cheese
made from whey protein concentrate-supplemented

whale milk O O O O O O O O O O O O O O O O O O O
Protein fraction of Domiati cheeses made from whey
protein concentrate-supplementing whole milk . .

Color changes of fresh Domiati cheese made from
whey protein concentrate-supplemented
whale mi 1k O O O O O O O O O O O O O O O O O O O

Texture profile analysis Domiati cheese made from
whey protein concentrate-supplemented
whole milk . . . . . . . . . . . . . . . . .

Components in whey from Domiati cheese made from

whey protein concentrate-supplemented
whale milk O O O O O O O O O O O O O O O O O O O

xii

Page

229

230

231

232

233

234

Figure

10.

11.

12.

13

14.

Sche
adde

Perm
ultr
repr
resp

Rela
of p
obta

Comp
ultr

Comp
diaf

Comp.
Ultn

COmpI
ultr;

COEp1
duril

Comp.
duril

Disc:
dens;

DiSCc
densj

DiSc
densj
milk

DiSCc.

 

Disc
dEns .'
Iilk

LIST OF FIGURES

Figure

1.

2.

10.

11.

12.

13.

14.

Schematic diagram of Domiati cheese made with
added whey protein concentrate . . . . . . . . .

Permeation rate of whole milk during
ultrafiltration and diafiltration. A and B
represent diafiltration start and stop,
respectively. . . . . . . . . . . . . . . . . .

Relationship of permeation rate ( flux ) to volume

of permeate of whole milk, skim milk and whey
obtained during ultrafiltration. . . . . . . . .

Composition changes in whole milk during
ultrafiltration. . . . . . . . . . . . . . . . .

Composition changes in whole milk during
diafiltration. . . . . . . . . . . . . . . . . .

Composition changes in skim milk during
ultrafiltrationO O O O O O O O O O O O O O O O O

Composition changes in sweet whey during
ultrafiltrationO O O O O O O O O O O O O O O O O

Composition changes in permeate of whole milk
during ultrafiltration. . . . . . . . . . . . .

Composition changes in permeate of whole milk
during diafiltrationO O O O O O O O O O O O O O

Discontinuous polyacrylamide gel electrophoresis
densitograms of whole milk retentate. . . . . .

Discontinuous polyacrylamide gel electrophoresis
densitograms for casein of whole milk retentate

Discontinuous polyacrylamide gel electrophoresis
densitograms for total albumin nitrogen of whole
milk retentate. . . . . . . . . . . . . . . . .

Discontinuous polyacrylamide gel electrophoresis
densitograms for casein of skim milk retentate.

Discontinuous polyacrylamide gel electrophoresis

densitograms for total albumin nitrogen of skim
milk retentate. . . . . . . . . . . . . . . . .

xiii

30

46

48

53

54

57

58

60

61

80

81

82

84

85

riqure

15. Di:
der

16. Dis
den
fire

17. Tex
Dom
Tes

18. Con
mad
8*]

l9. Har<
whol
7°C.

20. Gumn
who]
7°C.

21. Chev
whol
7‘c.

22. Cohe
at 7

23- Elas
whol
7°C.

24. Comp

ultr

non
25- Comp
conv
non
26. Ripe;
Conv.
nontl
27' Disc:
dEDSJ
CODVE

Figure

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

Discontinuous polyacrylamide gel electrophoresis
densitograms of whey retentate. . . . . . . . .

Discontinuous polyacrylamide gel electrophoresis
densitograms of conventional and ultrafiltrated
fresh Domiati cheese. . . . . . . . . . . . . . .

Texture profile curve of conventional and UF-fresh
Domiati cheese obtained with the Instron Universal
Testing Machine. . . . . . . . . . . . . . . .

Composition of protein fractions of Domiati cheese
made from UP whole milk and ripened in pouches or
8% brine at 7°C O O O O O O O O O O O O O O O O O O

Hardness changes on Domiati cheese made from UF
whole milk and ripened in pouches and 8% brine at

7°CO O O O O O O O O O O O O O O O O O O O O O O O

Gumminess changes on Domiati cheese made from UF
whole milk and ripened in pouches and 8% brine at

7°CO O O O O O O O O O O O O O O O O O O O O O O O

Chewiness changes on Domiati cheese made from UF
whole milk and ripened in pouches and 8% brine at

7°CO O O O O O O O O O O O O O O O O O O O O O O

Cohesiveness changes on Domiati cheese made from
U? whole milk and ripened in pouches and 8% brine

at 7°C O O O O O O O O O O O O O O O O O O O O O O

Elasticity changes on Domiati cheese made from UF
whole milk and ripened in pouches and 8% brine at

7°C O O O O O O O O O O O O O O O O O O O O O O O

Composition changes of Domiati cheese made by
ultrafiltration method and ripened for three
months in pouches. . . . . . . . . . . . . . .

Composition changes on Domiati cheese made by
conventional method and ripened for three
months in pouches. . . . . . . . . . . . . . .

Ripening index of Domiati cheese made by
conventional and UP methods and ripened for three
months in pouches. . . . . . . . . . . . . . . . .

Discontinuous polyacrylamide gel electrophoresis

densitograms of fresh and ripened (3 months)
conventional and ultrafiltrated Domiati cheese .

xiv

Page

87

104

109

120

133

134

135

136

137

144

145

150

156

rigun

28. ;
l
29. l
<
1
30. I
<
n
31.
32. E
33. p
s
34. c
s
35. T
W
t.‘
36. H.
WI
37- £1
£1
38. C}
f1
39. Dj
de
SI:
40. Co
ma
7A. TY.
fa1
SUI
9A. TY:

Figure Page

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

7A.

9A.

Texture profile curve of conventional and UF-
ripened Domiati cheese obtained with the Instron
Universal Testing Machine. . . . . . . . . . . . . 158

Hardness, cohesiveness and chewiness of Domiati
cheese made by conventional and ultrafiltrated
methods and ripened for 3 months in pouch. . . . . 159

Brittleness, elasticity and gumminess of Domiati
cheese made by conventional and ultrafiltrated
methods and ripened for 3 months in pouch. . . . 160

Color changes of fresh and ripened Domiati cheese
made by conventional and ultrafiltration methods. 162

Yields and yield efficiencies of Domiati cheese
made from WPC supplemented whole milk. . . . . . 170

Protein fraction of Domiati cheese made from WPC
supplemented whole milk. . . . . . . . . . . . . 175

Color changes of Domiati cheese made from WPC
supplemented whole milk. . . . . . . . . . . . . 181

Texture profile curve of Domiati cheese made from
WPC supplemented whole milk curves obtained with
the Instron Universal Testing Machine. . . . . . 183

Hardness and cohesiveness of Domiati cheese made from
WPC supplemented whole milk. . . . . . . . . . . 184

Elasticity and brittleness of Domiati cheese made
from WPC supplemented whole milk. . . . . . . . . 185

Chewiness and gumminess of Domiati cheese made
from WPC supplemented whole milk. . . . . . . . 186

Discontinuous polyacrylamide gel electrophoresis
densitograms of Domiati cheese made from WPC-
supplemented whole milk . . . . . . . . . . . . . 189

Components of whey released from Domiati cheese
made from WPC supplemented whole milk . . . . . . 19o

Typical gas chromatogram of the standard free
fatty acids (on 10 % SP-216-PS on 100/120
supelcoport) O O O O O O O O O O O O O O O O O O O 2 1 6

Typical gas chromatogram of the standard free
fatty aCids O O O O O O O O O O O O O O O O O O 19 o

pic]
Don:
coux

Feta

vari
manu

In E

INTRODUCTION

Soft white ” Domiati" cheese is the most popular
pickled cheese variety in Egypt and the Middle East (Abou-
Donia 1986). Variants are made in Europe and in many other
countries in South America. Domiati closely resembles Greek
Feta cheese.

Domiati cheese differs chiefly from other pickled
varieties in that it is salted at the very first step in its
manufacture: the salt is added directly to the milk.

In Egypt the manufacturing process for Domiati cheese can be
summarized as follows: One third of the cow's milk is heated
to 80 C, and salt (5-14%) is added to the remainder. The two
portions of milk are mixed, renneted and starter is added.
Coagulation takes place in 2-3 h at 38 C and the coagulum is
ladled into moulds of wood or steel lined with coarse cloth
or netting. The drainage time varies from 12-24 h (Abou-
Donia, 1986). The cheese is cut into blocks of convenient
size and wrapped in waxed paper. The cheese may be consumed
fresh. If the cheese is pickled, it is held in a salty whey
or brine for 4-6 months in layers in suitable tins
completely covered with brine . The tins are soldered and
then stored at refrigerator or ambient temperature.

Cheesemakers constantly strive to improve cheese

quality while seeking new technologies that offer higher

p1

ta

313

wt

ul

gr

a1

en

be

va‘

di:

ch!

Che

prc

inc

*1

2
production efficiencies. Since the late 1960's, membrane
technology has significantly evolved in its range of
applications to the dairy industry. Initially, the principal
application of membrane technology was the concentration of
whey and recovery of whey protein. The development of
ultrafiltration (UP) techniques for cheese making has shown
great promise 1 Covacevich and Kosikowski, 1978; Ernstorm et
al. 1980 and Kosikowski, 1980). Reduction in labor, energy,
enzyme requirements, manufacturing time, and work space may
be realized by utilization of UP techniques. By removing
water,lactose and minerals through UF, milk may be converted
directly to the solids content of certain high moisture
cheeses (Anon., 1980: and Maubois and Mocquot, 1975). Soft
cheese may be made from the concentrated retentate, and whey
proteins, which normally would be lost in the whey, are
incorporated into the cheese. The result is increased yield.
The objectives of the present investigation were:

* To study the effects of pilot plant scale UF on the
retention of milk, skim milk and whey components.

* To develop a process based on UF technology for making
soft white "Domiati" cheese and compare it with cheese
made from whole milk by conventional methods.

* To develop a vacuum packaging method for ripening of UP
cheese and compare it with the brine method of ripening.

* The feasibility of manufacturing Domiati cheese by
supplementing the whole milk with whey protein concentrate

(WPC) obtained by UP.

co
lo
we
Chi
inc
the

sol

com~
Dre:
Smal
a C1
spec
rete.
memb]
Passa
in a

membr;

RBVIE' 0? LITERATURE

The Concept of Ultrafiltration

Ultrafiltration ( UF ) is a technique for the
concentration of liquids using semipermeable membranes at
low temperatures and pressures to separate high molecular
weight from low molecular weight components without a phase
change. This process is gaining popularity in the food
industry and is of particular interest in some segments of
the dairy industry, since fluid milk and whey have low
solids and high moisture content.

Ultrafiltration membranes are designed to retain solute
components, depending on shape and molecular size. The
pressure gradient across the membrane forces solvent and
smaller species through the pores of the membrane, producing
a clear fluid known as filtrate or permeate. Large solute
species are retained and recovered as a concentrated
retentate ( Porter and Michaels, 1970 ). The nature of the
membrane controls the retention of some components and the
passage of others during direct ultrafiltration, resulting
in a selective concentration ( Cheryan, 1986 ). The

membranes often retain only macromolecules or particles

 

f]
so
so
as
sa.
911

Ric

dyn
in
the
UP
a '3
cOns

appl.

4
larger than about 0.001-0.02 um ( 10-200 angstroms ) or
particles that range from about SOD-1,000,000 in molecular
weight ( Porter and Michaels, 1970 : Cheryan, 1986 ).

Industrial ultrafiltration applications of milk and
milk products began in 1969 and many large installations
now are in operation throughout the world, especially in
Europe and the United States ( Kosikowski, 1986 ). During
ultrafiltration, milk enters the system under a combination
of pressure, temperature and high velocity to maximize the
flux rate through the membrane surface. This enables
substantial removal of water,lactose, soluble salts, and
some nitrogenous materials, which pass through the membrane
as permeate. Fat, proteins, and colloidal or insoluble
salts are retained in a decreasing pool of milk serum to
give a liquid concentrate ( retentate ) as reported by
Richter (1983) and Kosikowski ( 1986 ).

Peri et al. ( 1973 ) used this principle of membrane
dynamics to describe a method for adjusting lactose levels
in retentate. This is called diafiltration, and it involves
the controlled addition of water to the retentate during
UF, either stepwise or in continuous cycle . The effect is
a "washing out" of lactose to the levels that are
consistent with those of the desired product. The water
applied usually is equal the volume of permeate removed.

Successful application of ultrafiltration has been
reported for the manufacture of cheese, yogurt, fluid milk

drinks and whey protein concentrate ( Richter, 1983 ). Such

 

te
is
da
pr
L'l

ma:
be‘

19E

Ult

dis

Ski
int
Che
Phy
str

met:

5
techniques also serve as a replacement for conventional
isolation methods, thereby avoiding chemical or physical
damage or production of off flavor which may develop in such
processes ( Glover, 1971; Olsen, 1977; Cheryan, 1983 ).
Ultrafiltration is now an established unit operation for
the purification, fractionation and/ or concentration of
many liquid food systems, such as fruit juices, alcoholic
beverages, vegetable proteins and egg white ( Kosikowski,

1986; Nichols and Cheryan, 1981; Nichols and Cheryan, 1982)

Ultrafiltration Membranes

Mo1ecular membranes have evolved rapidly with
distinctive features ( Horton, 1979; Cooper, 1980 and
Lonsdale, 1982 ). Membranes have a thin surface layer, or
skin, where permeation occurs, and most have an open, porous
interior or packing to support the surface skin. The
chemical nature of the membrane governs compatibility and
physical properties to a large extent, while the physical
structure of the membrane is governed primarily by the
method of preparation ( Cheryan, 1986 ).

Two generations of UP membranes were successively
proposed and a third type is appearing. The first
generation used in the dairy industry is made of cellulose
acetate has now been abandoned because of several
disadvantages, including sensitivity to extreme temperature

( above 30°C ) and pH (limited to pH 3 to 8), sensitivity to

 

 

mic:
Chlc
re51
app:

str:

indL
most
198C
char
wide
avai
in n

Sani

min:
Mate
P01)
wide

80 I

UltI

sYst

hollc

6
microorganisms and disinfectants, and poor resistance to
chlorine sanitization ( Harper, 1979; Cheryan, 1986 ). As a
result, time-consuming cleaning procedures involving the
application of proteolytic enzymes were required, with
strict limitations set on pH, temperature and chlorine.

The second generation, widely used in contemporary
industrial processes, are made from synthetic polymers,
mostly polysulfonic or polyolefin derivatives ( Maubois,
1980; Kosikowski, 1986 ). These types of UP membranes are
characterized by higher limits of temperature (up to 75%:),
wide pH tolerance ( 2 to 12 ), wider range of pore size
available for UP applications ranging from 1000 up 500,000
in molecular weight cut-off, and good resistance to chlorine
sanitization ( up to 200 ppm ).

The third generation of UP membranes are made from a
mineral component ( zirconium oxide ). This membrane
material possesses improved qualities over those of
polysulfones, being resistante up to 400°C and tolerant to a
wide range of pH, and ability to withstand pressures up to

80 psi ( Maubois, 1979, 1980 ).

Ultrafiltration Configurations

Currently, there are several type of ultrafiltration
systems being used in the dairy industry. The most common
ones are the plate and frame membrane, the tubular membrane,

hollow fiber and the spiral wound membrane. Each of these

VS‘

per

 

and

won

of

Me:

to:

me:
st

pe:

lif,.il.

of

Vh

CE

er

it

7
systems has some advantages and disadvantages regarding
performance, investment and operating costs , dead volume
and cleaning efficiency ( Maubois, 1980 ). The spiral-
wound system, which was used in this investigation, is one
of the most compact and inexpensive designs available today.
Membranes are basically flat sheets arranged in parallel to
form a narrow slit for fluid flow. In this module,
membrane and supporting material are wrapped around-a
perforated stainless steal pipe and enclosed in a stainless
steel housing. Fluid feed material is pumped into one end
of the module and flows across the membrane. Permeate,
which passes through the membrane, is collected in the
center pipe while the retentate exits through the opposite
end of the housing. Although membranes are easily changed
in this system, some cleaning problems exist

( Harper, 1979; Richter, 1983: Cheryan, 1986 ).

The Mode of Operation

The main modes of operating an ultrafiltration system
are designated as single pass, batch and continuous.
The single-pass system is designed to concentrate the
product to the desired level in a single movement through
the membrane system and involves no recycling of the
retentate, which is a factor limiting the attainment of high
concentrations of the retentate ( Kosikowski, 1986 ). In the
batch system, the retentate is continuously recycled to the

starting supply tank through the module until the desired

t:

wi

se

in'

be:

Mot

ret
thr
mat.

Ros;

Am

and -
Cher:
1) it
Of mj
denat
pr°Pe.
began:
Protej

and tr

8
concentration in the retentate is obtained: meanwhile the
permeate is collected in another storage tank. A heat
exchanger is included in the recycle loop to control
temperature. The batch system is the fastest and the
simplest method for concentrating a given amount of material
with minimum membrane area.

In a continuous system, the retentate moves through a
series of modules and, before entering each module it passes
into a loop where an individual pump raises the pressure
before the retentate moves through the succeeding modules.
Modules can be arranged in series or in parallel. The
retentate becomes concentrated to high levels as it moves
through the system and is released. Meanwhile, fresh
material is supplied to the feed tank ( Richter ,1983:

Kosikowski, 1986 ).

Advantages and htnitations of or Processes

There are numerous advantages of UF processing of milk
and whey as reported by Bundgaard et al. ( 1972 ) and
Cheryan ( 1986 ). The most important advantages are:
1) increased cheese yield ( 10-20 % ) from a given quantity
of milk due to the recovery of whey proteins, ii) less
denaturation of protein with minimal loss of functional
properties, iii) higher nutritional quality of the products
because of the high protein efficiency ( PER ) of whey
proteins, iv) lower energy requirement for heating, cooling

and transportation of the products. Considerable savings in

 

manuf
50 tc
There
demo!
whey
appl:
the:
cont
limi
such
linj
solj
menu
col_
pm
in

SD]

9
manufacturing costs are expected, partially as a result of
50 to 80 % reduction in rennet and starter requirements.
There is a substantial decrease in the biological oxygen
demand ( BOD ) of the discharged wastes since little or no
whey is produced by the UP process. UF also facilitates the
application of continuous cheese processing and increases
the capacity of the cheese making equipment with minimal air
contamination. Despite these advantages, there are
limitations to ultrafiltration processing of dairy products
such as: i) the ultrafiltration membrane processes are quite
limited in their ability to concentrate milk to very high
solids content, ii) the decline in flux with time due to
membrane fouling from accumulation of macromolecular or
colloidal particles on the membrane surface.or the
precipitation of smaller solutes that are normally permeable
in the membrane pores, and iii) the poor cleanability of

some modules ( Cheryan, 1983 ).

Application of Ultrafiltration
in Dairy Products
Ultrafiltration is now an accepted processing
operation throughout the world. The two main applications
are the fractionation of cheese whey to produce whey protein
concentrate ( WPC ) and pre-concentration of milk for the

manufacture of fresh and ripened cheese.

 

or di
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ms
The partition of milk constituents by ultrafiltration

or diafiltration has received much attention and research.
Maubois et al.( 1969 ) were granted a patent for the use of
UP technology in cheese making. The process involves
passage of whole or skim milk across a porous membrane.
Removal of water and dissolved material is effected by
application of pressure. Practically complete retention of
fat and protein is achieved during concentration of milk by
HP (Ernstrom et al. (1980).

Kosikowski ( 1986 ) reported that the composition of
retentate and its stability at low temperatures were
contributing parameters affecting ultrafiltration processes.
The optimization of protein purification has been reported
by Peri et al. ( 1973 ), who used the principle of membrane
dynamics to describe a method of adjusting lactose levels in
the retentate by diafiltration. The process involved
"bleeding" deionized water into the ultrafiltration holding
tank at the same rate permeate was removed. The effect was
a "washing out" of lactose to levels that were consistent
with those of the desired product. Diafiltration was
carried out at constant volume in order to maintain a proper
balance between low retentate viscosity and high lactose
concentration in the water phase.

Several investigations have addressed the practical

limits of UP when used for production of milk retentate. An

impor
conce
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Yan ‘

flux
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important factor governing the extent to which milk can be
concentrated by ultrafiltration is the development of a
proteinaceous deposit on the membrane ( Glover et al., 1974:
Yan et al., 1979 ). This deposit, sometimes referred to as
the "secondary membrane", is responsible for the drop in
flux rate. Glover ( 1985 ) described the formation of the
secondary membrane as concentration polarization. After the
milk passes across the membrane under pressure, solids
collect on the membrane surface and inhibit filtration. Yan
et al. ( 1979 ) reported a decrease in flux with increasing
concentration of whole milk due to retentate viscosity and
development of the secondary membrane, whereas Fenton-May et
al. ( 1972 ) ascribed this effect to an increase in the
protein concentration in the retentate of skim milk. Glover
( 1985 ) proposed that high feed velocities during process
would produce shear forces that would inhibit the
development of the secondary membrane. Electron microscopy
and enzymic analysis of the deposit formed on reverse
osmosis ( RO ) membranes revealed a triple gel layer
composed primarily of casein ( Glover et al. 1974: Brooker,
1974 ). Closest to the membrane is a thin ( 11 nm ),
electronsdense layer which, probably, was deposited at the
beginning of R0. The second layer was thicker ( 10-15 nm )
and electron-lucent. The third layer was the thickest ( 30
nm ) and most diffused.

Brule and Fauquant ( 1965 ) investigated the effects of
acidification of milk and retentate on the levels of soluble

12

calcium. The amount of soluble calcium increased with
decreasing pH. Also, the amount of bound calcium in milk
and retentate increased linearly with temperature. Finally
they concluded that physicochemical characteristics of the
aqueous phase in milk retentate were responsible for the
equilibria of colloidal and solubilized mineral salts.
Ernstrom et al. ( 1980 ) demonstrated that removal of
calcium during UF of whole milk could be enhanced by
performing this process at pH 5.7. However, decreased flux
rate and frequent membrane fouling were the problems
associated with acidified milk.

Ultrafilterating whole milk of the dairy farms has
received serious attention and was pioneered by Maubois
( 1979, 1980 ). It may be desirable to concentrate milk to
double or triple concentration at the farm to decrease the
number of milk collections and final volume, resulting in
potential economies in transportation. The permeate
obtained from this procedure, containing lactose, soluble
salts, non-protein nitrogen, and vitamins, can be fed to
farm animals. The incorporation of UF units into farm

milking systems has been described by Slack et al. ( 1982 ).

W

Industrial scale manufacturing of soft cheese from
ultrafiltered milk is currently practiced in Europe and in
the United States ( Bundgaard et al.,1972: Anon, 1980 and

Kosikowski, 1986 ). The cheese industry has sought to

13

capitalize on the potential of ultrafiltration to increase
product yield and decrease production costs. Traditional
cheese making has been defined as a "fractionation process
by which fat and casein are concentrated in the curd by the
action of the enzyme , while lactose, soluble proteins,
minerals and vitamins are lost in the whey fraction ". The
yield of curd is typically 9-16 % of the weight of the milk,
leaving 84-91 % in the form of whey ( Kosikowski, 1986 ).

The use of ultrafiltration has change this concept
somewhat as the retentate ( pre-cheese ) has the same
composition as the final cheese in terms of fat, protein and
moisture. Also, whey proteins are incorporated into the
cheese rather than drained off with the whey. Mann (1982)
discussed the status of the application of ultrafiltration
of milk for cheesemaking and referred to several patent
applications and current commercial utilization of
ultrafiltration processes throughout the world.
Ultrafiltration allows for the adjustment of concentration
and proportion of principal components of milk to aid in the
mechanization of cheese manufacturing. It also increases
the recovery of milk components in cheese and controls the
selected properties of the cheese. A number of procedures
for manufacturing cheese from UF-milk have been developed.
Each procedure may influence cheese quality and composition
in a characteristic ways ( Mann, 1982). Two very basic
concepts for making cheese are: first concentrating and

adjusting milk to the composition of the cheese to be made

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14
and, second using traditional cheesemaking techniques in
which retentate of varying concentrations were used instead
of milk. Maubois and Mocquot ( 1975 ) reviewed several
methods of soft cheese making by ultrafiltration. An
increase in yield is achieved by UF techniques as a result
of retaining albumin and globulin when compared to the
conventional procedures for processing high moisture cheese.
Covacevich and Kosikowski ( 1977a ) and Yan et al.( 1979 )
provided a description of early laboratory scale UF systems
and their use in concentrating milk for production of high
moisture cheese such as Camembert, and a goat's milk cheese
called Feta.

Bacteriological, biochemical, and physico-chemical
criteria for these cheese making procedures are reviewed by
several investigators. It was suggested that UF of skim
milk should proceed for no longer than 5 hr at a UF
temperature of 50 to 54°C to preserve milk quality.
Ultrafiltration for longer periods at these temperatures may
promote bacterial growth and damage proteins. Garnot and
Corre ( 1980 ) studied the influence of protein content of
ultrafiltered milk on the action of milk-clotting enzymes
and subsequent clotting times of milk. Reuter et al.

( 1981 ) and Green et al. ( 1981 ) demonstrated that rates
of firming of curd formed from ultrafiltered milk increased
in proportion to the extent of concentration of the milk.
Green et al. ( 1984 ) presented data on whole milk
retentate obtained by ultrafiltration which suggested that

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15

cheeses made by ultrafiltration processes would be
comparable to conventionally made cheese with respect to
contents of water soluble vitamins. Brule et al.(1974)
discussed the mineral content of products from milk
concentrated by UP and demonstrated the feasibility of
producing a retentate with the necessary mineral content for
cheesemaking. The use of UF to concentrate and separate
milk constituents has far-reaching effects, especially for
soft and semisoft cheese ( Setti and Peri, 1976: Kosikowski,
1983 : Barbar and Bynum, 1984 and Zall, 1984 ).

2g;a_ghgg§g. Feta is a high-moisture, white cheese
which originated in southeastern Europe and Asia. It is
characterized by high salinity and a sharp taste.
Ultrafiltration offers an interesting and profitable
alternative to the conventional methods of manufacture by
increasing the yield by about 25 %, but the structure of the
cheese is slightly different ( Anon., 1980a ). In Denmark,
almost all Feta cheese is produced by UF techniques, with
nine Danish Feta cheese plants in operation (Anon., 1980b).
In the process, whole milk is ultrafiltered and the
retentate passed into a holding vat for adjustment of
composition to that of the final cheese. Yoghurt culture
and calcium chloride are added followed by the addition of
rennet and subsequent coagulation. Following drainage of
the free whey and when the pH drops to 5.0, blocks are
formed, dry-salted and placed in tins. A yield increase of

30% over conventionally produced Feta cheese was claimed

16

(An18,1984).
Qgfigggg_ghgggg. Matthews et al. ( 1976 ) developed a
procedure for making Cottage cheese from skim milk
retentates. Three separate lots of skim milk ( 9.0 % total
solids ) were concentrated by UP to total solids contents of
12.2, 12.9, and 13.1 % and made into cheese by conventional
method. Yields of Cottage made from the three retentates
were similar to that of the control which was made from skim
milk. Flavor and texture scores were acceptable although
some cheese curd exhibited a tough texture. Covacevich and
Kosikowski ( 1978 ) studied the feasibility of producing
Cottage cheese from retentate concentrated five fold. The
final product displayed a good flavor but the curd was
gelatin-like and possessed poor absorptive qualities when
cream dressing was added. The color and general appearance
of the cheese was poor. Diafiltration of the retentate
prior to fermentation improved overall cheese quality.
Jepsen ( 1979 ) has suggested that concentrating the milk to
two fold should decrease the required starter culture for
making cottage cheese by 50 % and double the capacity of the
plant. Also cottage cheese was produced by direct
acidification of the retentate through the slow addition of
glucono-delta-lactone to pH 4.8. The curd cut easily,
cooked well, and had good quality. And the final creamed
curd was considered excellent in flavor and texture.

ng§|_gngggg. Covacevich and Kosikowski ( 1977b )

reported that cream cheese produced from ultrafiltrated milk

showe
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the 1

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17
showed excellent shelf-life and smoothness, comparable with
standard commercial cream cheese but with much greater
hardness of body. Maubois ( 1979 ) reported that adjusting
the mineral content of UP cheese solved the texture
problem.

Biggi§§_ghgggg. Maubois ( 1979 ) developed a complete
mechanized process for the continuous production of Ricotta
cheese which had higher yield and good sensory properties.

Qghg;_fig:t_gngggg. Soft, mold-ripened cheeses such as
Camembert have been made successfully using ultrafiltration
procedures ( Kosikowski 1974, 1986: Maubois, 1979 ). These
cheeses were satisfactory in yield, appearance, flavor and
texture.

A Danish blue cheese manufactured at a Danish dairy
plant using a UF process was described by Jepsen ( 1977 )
and reported to be of sufficiently high quality to justify
export. Mahaut and Maubois ( 1978 ) reported that blue
cheese made from retentate possessing between 4-12% protein

exhibited better sensory qualities than the control cheese.

WWW

Alternative ultrafiltration techniques are possible
with LCR ( low concentrated retentate ) where highly
concentrated milk or whey retentate is added to cheese milk,
after which cheesemaking proceeds in the traditional manner.

The supplementation of skim milk or whole milk with

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retentate offers potential in cheesemaking for shorter
setting time, rapid acid development and reduced rennet
requirements. Acid flavor was the only significant defect
associated with cheese containing concentrated whey (Richter
1983 ). Further investigations by several researchers
( Kosikowski 1979, 1981: Kealey and Kosikowski 1982:
Fernandez and Kosikowski 1983: Massaguer-Roig and Kosikowski
1983 ) showed that optimum cheese quality is attained with
retentate supplemented milk mixtures adjusted to a milk:
retentate protein ratio between 1.4:1 and 1.8:1 for Cheddar
cheese, Cottage cheese, Mozzarella, and Queso Blanco.

Abrahamsen ( 1979 ) investigated the possibility of
manufacturing hard and semi-hard rennet cheese of acceptable
quality from milk fortified with different amounts of whey
protein concentrate. He obtained increased yields of cheese
depending on the manufacture procedure. Brown and Ernstrom
( 1982 ) studied the benefits of incorporating UF-whey
concentrate to cheddar cheese milk and found that such
incorporation increased the yield by 4%. The cheese had a
higher moisture content and lower fat content than the
cheese made by a conventional method. Specific body,

texture and flavor characteristics were identified.

WM
Domiati cheese, the most popular soft, white-pickled

cheese variety in Egypt, is usually consumed either fresh or

after a ripening period varying from two to four months.

19
The cheese is made from fresh or reconstituted whole or
skimmed buffalo or bovine milk, or from a mixture of both.
However, a specified amount of fat is added if skimmed milk
is used for making Domiati cheese. Increasing demand for
this cheese conflicts with a market shortage in the fresh
milk supply. Several investigations were directed to solve
this problem by incorporating the ultrafiltration technique
into the manufacturing process. Omar ( 1987 ) studied the
physical and chemical composition of cheese made from
ultrafiltered, reconstituted milk and compared it with
conventional cheese produced from recombined milk.
According to this study the ultrafiltered milk cheese was
characterized by a higher content of moisture, protein and
fat in the dry matter, higher buffering capacity and pH than
that of the cheese prepared by conventional method. Abd
El-Salam et al. ( 1981 ) studied the ripening of Domiati'
cheese made from ultrafiltrated Buffalo skim milk mixed with
fresh cream. The cheese stored without brine solution,
showed less weight loss as compared to the cheese ripened in
brine. Mahmoud et al. ( 1983 ) developed a method for
making Domiati cheese from UF reconstituted skim milk and
lipolyzed recombined cream. Organoleptic scoring revealed
that the cheese made with cream which had been treated with
an intermediate level of lipase ( 2 or 5 g/500 9 cream ),
ranked highest in flavor after one and four months of
storage. El-Shibiny et al. ( 1983 ) investigated the

possibility of using vegetable oils in making soft cheese

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20
from UF recombined milk and observed that replacement of
milk fat with vegetable oil up to 100 % had no significant
effect on the chemical composition or weight loss during
storage. A slight oily flavor was observed in fresh cheese,
especially when cottonseed oil was employed. During
storage, this oily flavor was greatly reduced. Abd El-Salam
and El-Shibiny ( 1982 ) explored the influence of rennet,
rennet substitutes and different starter cultures on the
composition and quality of Domiati cheese made from
recombined milk which was concentrated by ultrafiltration.
They reported that all the cultures used gave the same
effect on cheese composition and quality, while rennet
affected protein breakdown and weight lose during storage.
Ernstrom and Anis ( 1985 ) studied the effect of
incorporating heated retentates in the production of soft
white cheese similar to Domiati varieties made in the Middle
East. They reported that this type of cheese can be made
from UF whole milk by heating the retentate to at least
180° F for 30 min prior to culturing and setting with
controlled pH. Mahmoud and Kosikowski ( 1979 ) also studied
the ripening of Domiati and Feta cheeses made from
ultrafiltrated skim milk. The resulting cheese obtained in
higher yield and possessed more flavor than the
traditionally ripened cheese. El-Gendy et al.( 1983 ) and
Omar ( 1987 ) observed that quality Domiati cheese made from
ultrafiltrated cows' milk had a uniform and closed texture,

good appearance and improved organoleptic properties. The

d2

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21
data showed that the breakdown of protein with the
'accumulation of free amino acids and the liberation of
volatile free fatty acids were faster in UF-cheese than in

cheese made by a conventional method.

W

Whey is a highly nutritious by-product of cheese and
casein manufacture and it contains about 0.9 % protein, 0.1
% fat, 0.5 % ash and 4.9 % lactose. The whey proteins
represent the non-casein proteins as well as the fractions-
and fragments of the casein which remain soluble when
casein has been precipitated enzymatically by rennet or
isoelectrically by acid.

Total world cheese whey production is estimated to be
about 187.4 billion lb, which would contain about 133.8
million lb of whey proteins ( Zall, 1983 ). Approximately
50 percent of the total whey solids are disposed of by
various industrial and municipal waste treatment systems and
only five percent used for manufacturing whey protein
concentrate ( WPC ) by ultrafiltration (Morr 1984). Only 50
% of the WPC is processed further ( Spangler and Amundson,
1986 ). Whey contains highly desirable nutritional
proteins which also possess good functional properties. The
nutritive value of whey is essentially related to its high
content of essential amino-acids especially cystine, lysine,

leucine, isoleucine and threonine ( Hambraeus 1982 ).

22
Dehydrated whey contains only 10-12 % protein, but when
concentrated by UP and dehydrated, the powder consists of 50
to 80 % protein ( Ritcher, 1983 ). The composition of WPC
produced by UF was reported by Morr et a1. ( 1973 ) and
Marshall ( 1982 ). Most WPC is dried and is widely used in
foods such as cheese supplement, ice cream, bakery products
and confectionery applications where the functional
properties of the proteins are required and high quality
nutritional protein is desired ( Richter, 1983 ). One major
advantage of WPC over casein products is the high degree of
solubility in acidic food products. This unique property of
WPC was used for improving the nutritional quality without
adversely altering the sensory characteristics of the food
products. UF has emerged as the most appropriate process
for industrial manufacture of WPC, and advances are being
made in the design and operation of this process ( Wesley,
1981 ). After concentrating whey by UP to 18-22 % protein
content, the retentate is pasteurized and spray dried under
mild conditions to minimize protein denaturation that would
adversely alter protein solubility and functionality. The
primary use of UP is to produce WPC that can be marketed
more profitably than the conventionally dried whey powder.
Whey protein concentrate competes economically with protein
ingredients such as non-fat dry milk ( NFDM ), casein and
egg albumin in major product categories. Morr (1984) stated
that whey solids in the form of WPC which contain more than

35% whey proteins, with lower lactose and mineral contents,

 

are no]

replac:

23
are more suitable than dried whey or concentrated whey for

replacing NFDM in many food formulations.

HATERIALB AND METHODS

Preparation of Retentate

Raw, whole cow's milk and skimmilk used for this study
were obtained from the Michigan State University Dairy
Plant. The milk was pasteurized at 63°C for 30 min. and

cooled to 50°C .

Sweet whey used for ultrafiltration processing was
obtained from manufacture of Cheddar cheese at MSU Dairy
Plant. Salted whey was obtained from pilot plant production
of Egyptian Domiati cheese in which 7 % ( w/w ) salt was
added to the milk before manufacture. The whey was
clarified by centrifugation to remove curd fines, followed
by pasteurization at 63°C for 30 min. and cooling to 50°C

before ultrafiltration.

111W”
An S-l ultrafiltration system equipped with an HFK-131,

Spiral-wound, polysulfone membrane with 5 m3 of filtering
surface and a nominal molecular weight cut-off of 5,000

Daltons ( Koch membrane system, Inc., Wilmington, MA USA )

24

ml

V.

Eli

01
di
5C
Fe
Co
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CO
19.

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25
was used in the batch mode. An inlet pressure of 50 psi and
outlet pressure of 30 psi were used throughout the
operation.

Thirty gallon lots of whole milk, skim milk or whey
were held in a jacketed, stainless steel vat ( 100 gallon )
which served as the feed tank to the ultrafiltration unit
and recycled from the feed tank to the UP membrane, passing
through a heat exchanger to maintain isothermality. The
operation continued until the retentate reached a desired
concentration or the permeate no longer passed through the
membrane ( very low flux ). Once the desired concentration
was attained, the retentate was placed in 3 liter plastic
containers, and stored at -20°C for later use in cheese
manufacture.

During the concentration of whole milk, using
diafiltration, the milk was concentrated until 60 % ( V/V )
of the milk was removed as permeate. At this point,
diafiltration was started by introducing deionized water at
50°C to the retentate as described by Vieira et al. (1983) .
Following diafiltration, an additional recirculation was
continued until 80 % of the original milk was removed as
permeate, resulting in a retentate possessing a volume
concentration ratio ( VCR ) of 4.5. ( Ernstrom et. al.,
1980). After processing, the system was cleaned as follow:
rinsed with 30 gallons of deionized water at 50° C: followed

by 20 min recirculation of phosphoric acid ( 250 mL/25

oi
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26
gallons of water ) and finally rinsed with water follow by
circulation of 10 gallons of 200 ppm available chlorine
solution. The ultrafiltration unit was sanitized
immediately before use with water containing 150 ppm
chlorine as recommended by the manufacturer.

To monitor the effect of the ultrafiltration and
diafiltration processes on milk and whey composition,
retentate and permeate samples were taken at appropriate
intervals during the operation. Samples were frozen at
-20°C for subsequent chemical analysis. Permeation rate was
determined by a measurement of permeate flow ( mL/min.) and

dividing by the system's active membrane surface area.

Cheese Manufacture From Whole Milk

We:

Domiati cheese was made from pasteurized cow's milk
in 10 gallon stainless steel vats resting in an insulated
metal container as outlined by Ibrahim ( 1963 ) with minor
modification. Milk was divided into two portions and 5 %

( w/w ) sodium chloride was added to one half. Thawed,
frozen concentrated lactic starter (Redi-Set DVS, Chr.
Hansen's laboratory, Inc., Milwaukee, WI) was added ( 0.015
% v/v ) to the second (unsalted) portion at 35°C. After
ripening for 20 min., the two portions were mixed together
and coagulated with 0.025 % single strength microbial rennet

(Emporse SF-100, Dairyland Food laboratories, Inc.,

W81

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130
Mu
wa.

we.

16
181
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the

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in

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27
Waukesha, WI). The smooth gel obtained after 105 min was cut
with 1 cm wire knives lengthwise and crosswise and left
undisturbed for 15 min. Following the removal of whey, the
curds were dipped into round molds 10 cm in diameter and 14
cm high to drain over night at room temperature. Cheeses
were sealed under vacuum in polyethylene-lined aluminum
pouches, 26 cm x 16.5 cm (Fisher Scientific), using a
Multivac, type AGW Vakuum Verpackungs Maschinen. The Cheese
was ripened at 7-10°C for 3 months. Representative samples

were analyzed at intervals of one month.

21W
Liquid pre-cheese retentate was heated to 71.6°C for

16 sec and cooled to 35°C, then inoculated with 0.07 %
lactic acid starter, poured into 0.45 Kg cottage cheese
containers and ripened for 10 min. Rennet ( 0.09 % ) was
added to each container to induce complete coagulation in
8-10 min. A firm cured was obtained with a little whey
exudation. Five percent salt was spread on the surface of
the cheese which was ripened in polyethylene pouches for 3

months at 7-10°C. Samples were analyzed monthly.

W
The retentate obtained by ultra/diafiltration of whole

milk was spread over aluminum trays ( 11 1/4 x 7 1/2 x 1 1/2
in ) for the freeze-drying experiment. Each tray was sealed

with freezer tape and frozen immediately at - 209F. A

28

Virtis REPP, Model FFD 42 WS freeze-dryer, with a capacity
of 50 lb of water removal per drying run, was employed in
these studies. The freeze-dryer was equipped with
instrumentation for the control of freeze-drying variables.
Automatic controls for condenser and platen temperature,
vacuum adjustment, weight system recorder for determination
of drying curves, constant recording of absolute pressure
and thermocouple connections were controllable with this
unit. Operating conditions employed were: 20 microns Hg
absolute pressure, platen temperature of 125°F, and
condenser temperature of -65°F. Samples were removed when
product temperature had reached 85°F. After completion of
drying, nitrogen ( W/P ) was introduced into the vacuum
chamber to establish atmospheric pressure. The freeze-dried
powder was removed from the tray, screened, put into small,
brown-glass jars, tightly sealed and stored at 5°C until
used. Freeze dried retentate was reconstituted in warm
water ( 40°C ) to the same composition of the liquid
pre-cheese, then blended with a mixer (Ultra-Turrax Model
SDT 1810, Tekmar Company) for 5 min. Following heat
treatment to 71.6°C for 16 sec. , the reconstituted retentate
was cooled to 35°C and used in the preparation of Domiati
cheeses as described in the section on ultrafiltration.

Cheeses were ripened by two method, in 7% brine
solution and in vacuum pouches for 2 months at 7-10°C and

analyzed at two week intervals.

29

Cheese from Whey Protein Concentrate
Supplemented Whole Milk

Fresh whole milk was pasteurized at 71.6°C for 16 sec
and then cooled to 35°C. Concentrated whey protein was
'obtained by ultrafiltration of whey produced from Domiati
cheese manufacture by the conventional method. The
concentrated whey was kept frozen at -20°C until used for
supplementation of the whole milk for Domiati cheese making.
The WPC was heat-treated to 75°C for 30 min with gentle
agitation and cooled quickly to 35°C. Whole milk was
fortified with the heat-treated WPC to give progressively
increasing total protein concentrations ranging from 1:0
(unsupplemented control) to a maximum of 1:2 in the
mixture. Domiati cheese was produced by the traditional
method from whole milk supplemented with WPC ( Figure 1 ).
Whole milk was divided into five equal portions of 5 Kg
each. The first portion represented the unsupplemented
control while the other four portions were supplemented with
WPC. The amount of WPC added to the milk was 25, 50, 75,
100 or 200 % based on the original total milk protein. The
mixture was inoculated with 0.15 mL/L of frozen,
concentrated lactic starter ( Redi-Set DVS, Chr. Hansen's
laboratory, Inc., Milwaukee, WI ) and held for 20 min.
Single strength rennet ( SF-100, Dairyland Food

Laboratories, Inc., Waukesha, WI ) was added at the rate of

30

 

 

Tradltlonal
cheese maklng

 

 

1

w Whey I
O

 

 

\

 

Cheese

 

 

 

 

 

UF-Operatlon

 

 

 

v

 

 

Retentate (WPC)j_. Permeate

 

 

 

Different Ratio... 1

 

Whole mllk

 

 

 

fl

 

 

 

Cheese maklng

 

4—-starter
<— Rennet

 

WPC-supplemented

cheese

Figure 1. Schematlc diagram of Domlatl cheese
made tram WPC-supplemented whole mllk.

 

0.3 mm
at the t
calculat

was reps

31
0.3 mL/L of mixture. Each batch of cheese curd was weighed
at the time of hooping and the yield of cheese was
calculated following draining for 48 hr. Each experiment

was repeated three times.

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32

CHEMICAL ANALYSIS

The composition of the milk, whey, retentate, permeate
and the cheese produced were determined using the following

methods.

25

Ten grams of cheese were slurred with 40 mL of
deionized, distilled water in a Waring semi-micro blender
for 2 min. The slurry was immediately transferred to a
glass beaker and pH was recorded with an Orion Research
Model 301 pH meter. The pH of the fluid samples was
obtained directly on the product without dilution.

W
Total solids of fresh milk, whey, retentate,

permeate and cheese were determined by a vacuum oven method

at 100°C to constant weight ( AOAC, 1984 ).

m
The fat content of milk was measured by the Babcock

procedure (AOAC, 1984). Milk and whey retentates, and
cheese samples were determined by the modified Babcock

procedure ( Kosikowski, 1977) .

m]
hc
Vc
as
a1
10

di:
No!
fil
Get

”it

33
£31!
Determination of salt in cheese,milk retentate,and whey
samples was performed by a modified Volhard test described

by Kosikowski ( 1977 ).

21:23:11.1:
The micro-Kjeldahl method ( AOAC, 1984 ) was used for

the determination of total nitrogen (TN ), non-casein
nitrogen ( NCN ), non-protein nitrogen ( NPN ), and total
albumin nitrogen ( TAN ).

sample Preparation

For the determination of the reduced nitrogen
fractions, a sodium citrate-cheese extract was prepared by
weighing 10 g of cheese and blending in a Waring
micro-Blender with 40 mL of sodium citrate ( 0.5 N ) and 80
mL of distilled water for 7 min at high speed. The
homogenate solution was quantitively transferred to a 200 mL
volumetric flask and tempered to 20°C with distilled water
as described by Vakaleris and Price ( 1959 ). A 10 mL
aliquot was taken for determination of TN. An aliquot of
100 mL of sodium citrate cheese extract was adjusted to pH
4.4 by adding 10 mL of 1.14 N HCL and made to 125 mL with
distilled water. The mixture was filtered through a Whatman
No. 42 filter paper and an accurate portion of the clear
filtrate, which contained soluble nitrogen, was used for
determining NCN. Twenty mL of a pH 4.4 filtrate was treated

with 80 mL of 15 % trichloroacetic acid and filtered through

f 11
mic
pre
nor.
the
4 0%
3O

Tot

det

Dre
(19
dis
lire
Eff
min
at g

2‘11]:

34

Whatman No.42 filter paper ( Grippon et al., 1975 ). The
filtrate containing the NPN fraction was assayed by
micro-Kjeldahl. Because of the ability of sodium sulfate to
precipitate all nitrogen fractions except total albumin and
non-protein nitrogen ( whey protein ), a 20 mL aliquot of
the sodium-citrate cheese extract was mixed with 20 mL of a
40% sodium sulfate solution at 45°C and allowed to stand for
30 min and then filtered through Whatman No.4 filter paper.
Total albumin nitrogen and non-protein nitrogen were
determined in this filtrate ( Aschaffenburg, 1959 ).

Additional nitrogen fractions were derived from the
above four fractions determined as follow : Casein nitrogen
( CN ) was equal to TN minus NCN and the total albumin N

(TAN ) was equal to ( TAN+NPN ) minus NPN.

We

sample Preparation

Samples of milk, whey, retentate and cheese were
prepared following a procedure described by Ledford et al.
(1966) with some modification. Two hundred mg of cheese was
dispersed in 0.8 mL of distilled water and 2.0 ml of 7 M
urea was added. Samples were warmed to 37°C for 1 hr to
effect a layering of fat and centrifuged at 2000 rpm for 10
min at 10°C. The supernatant was dialyzed against 7 M urea
at 5°C for 24 hr to remove the salt. Two drops of

2-mercaptoethanol were added to the sample, which was held

for
ele-
suc
mil
for
(M
iii
id
ar.
e]

SC

35
for 2 hr at 37°C to visualize kappa-casein by subsequent gel
electrophoresis. Ten mL of 1% bromophenol blue and 125 uL
sucrose solution were added prior to electrophoresis. All
milk and whey samples were dialyzed against distilled water
for 48 hr at 5°C. Standards of a-Casein, B-Casein,
fi-Lactoglobulin and a-Lactalbumin, isolated from bovine
milk (Sigma Company ,St. Louis, MO.), were used for
identification and comparison with the samples ( Swaisgood
and Brunner, 1973 ). A standard was included in each of the
electrophoretic run. Procedures for the preparation of
solutions and electrophoretic gels are included in

Appendix (1).

Electrophoretic and staining procedure

Electrophoresis was carried out in 9% polyacrylamide
gels in a vertical, water-cooled Bio-Rad, Model 150A,
electrophoretic apparatus according to a method essentially
similar to that of Ornstein and Davis ( 1964 ).
Electrophoresis was performed at 1 mA/tube for the first 10
min and subsequently at a constant current of 3 mA/tube
supplied by a MRA Corporation Model M158 Automatic power
supply. The gels were removed from the pyrex tubes and
stained in Comassie Brilliant Blue R-250 ( Sigma ) overnight
and destained by diffusion for 24 hr in a mixture of acetic

acid:methanol:distilled water 4:10:86 ( v/v ).

36

Gel Densitometry

Gels were scanned using a Beckman DU spectrophotometer,
Model 2400 equipped with a gel scanner Model 2520 and a
photometer, Model 252 (Gilford Instrument Laboratories). The
system was augmented by a Hewlett-Packard Integrator , Model
3380s. The gels were scanned at a wavelength of 580 nm at a
rate of 1.0 cm/min. Results were recorded at a chart speed
of 2.0 cm/min. Relative areas of the individual proteins
were calculated and recorded from integration signs on the

densitograms.

mm

Picomole quantities of total and free amino acid were
determined according to the HPLC method of Cohen et a1.
( 1986 ). Whey , final retentate ( WPC ) and extracted
cheese were hydrolyzed in 6N HCl at 110 C for 20 hr.

Preparation of Cheese Sample

The samples were prepared by weighing accurately 10 g
of cheese, homogenizing in a Waring micro-Blender with 100
mL of redistilled water for 2 min. The slurry was removed
and heated to 75°C with agitation for 5 min and cooled to
room temperature. Equal volumes of slurred cheese and 24 %
TCA were mixed. The resulting solution was allowed to stand
30 min, centrifuged at 2000 rpm for 10 min at 5°C and
filtered through Whatman No. 42 filter paper. To remove

the residual TCA, the supernatant was washed with an equal

vol
upp
tim
sol
let

for

cm
111
de

in

37
volume of ethyl ether (1:1), using a separatory funnel, the
upper layer was removed. This step was repeated three
times. To remove the majority of remaining peptides, the
solution was mixed with absolute ethanol (1: 4 v/v) and
left undisturbed for 12 hr before centrifuging at 10,000 rpm
for 30 min, which was followed by filtration through a
Millipore 0.45 um filter (Kosikowski, 1951). An aliquot
containing 10 mg of protein was hydrolyzed with 6N HCl at
110°C for 20 hr. Thirty uL of the hydrolysate was used for
derivitization with phenylisothiocyanate (PITC) as described

in Appendix 2.

£12321:

The lactose content was determined by the phenol-
sulfuric acid method of Dubois et al.(1965). One hundred mg
of milk , whey ,retentate or cheese sample was made up to
100 ml with distilled water and mixed thoroughly. Two mL of
this solution was added with 1 mL of 5 % mixture of
redistilled phenol in a test tube. Five mL of concentrated
sulfuric acid was added rapidly while the tube was agitated
to insure maximum mixing and heat development. The samples
were allowed to stand at room temperature for 10 min and
the absorbance was read at 490 nm using a Spectronic 2000
(Bausch and Lomb) spectrophotometer. A standard curve for
lactose was constructed to cover a range of concentration

from 0 to 225 pg.

coup
Jar:

19 e

ali
nit

Tai

10
fir
(A;

CO

Pu.

(]

0!

[an

38
Linen].

Minerals analysis was performed using an inductively
coupled plasma (ICP) Atomic Emission Spectroscope,
Jarrel-Ash Model 955, equipped for simultaneous analysis of
19 elements as described by Braseton et a1. (1981).

Sample preparation

Samples were sonicated for one-half hour and one gram
aliquot (wet weight) were combined with 2 mL of concentrated
nitric acid in a 15 mL screw-capped, Teflon vial (Tuf-
Tainer, Pierce Chemical Co.). Samples were incubated at
95-100°C over night, cooled, and quantitively transferred to
10 mL volumetric flasks. Yttrium (Y) was added to give a
final concentration of 1 ug/mL as an internal standard
(Aldrich Gold Label, 99.999% or better, Aldrich Chemical
Co.). Samples were diluted to the final volume with water
purified with a four-bowl Milli-Q Water Purification System
(Millipore Corp.) and analyzed by inductively coupled plasma
(ICP ) spectroscopy. Instrumental parameters were
optimized and the final operating conditions are given in

Appendix 3.

Wide
The method described by Deeth et al. (1983) for the

isolation and quantitative determination of free fatty acids
( FFA ) in milk, retentate and cheese was used. Separation
of FFA and lipids was done by placing 5 g of grated cheese

or fluid sample in a screw-capped test tube (18 mm x 150 mm)

cor
(c7
sta
ble
Ins
of
wit
sod
sar
for
The
chr
dea
neu
was
Was
rem
ads
Out
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add.
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detE

39
containing 25 mL of dimethyl ether, 100 ug of heptanoic acid
(C7) and 100 ug heptadecanoic acid (C17) as internal
standards and 0.5 m1. of 5.5 N H280," The mixture was
blended thoroughly with a Brinkmann homogenizer (Brinkmann
Instruments Co. Westbury, NY) at speed 7 for 30 sec. Ten mL
of hexane were used for rinsing the probe twice and combined
with the sample extract. Approximately 12.5 g of anhydrous
sodium sulfate was added to the test tube containing the
sample extract. The test tube was centrifuged at 700 x g
for 5 min. (IEC Clinical Centrifuge, Needham Heights, MA).
The supernatant was added carefully to a glass
chromatographic column (17mm x 265mm) containing 5 g of
deactivated neutral alumina (Chromatographic alumina
neutral, activity grade 1, Sigma (chemical Co.). The eluate
was passed over the column for the second time, followed by
washing with 10 mL of hexane:dimethyl ether (1:1, v/v) to
remove other soluble materials. The alumina, containing
adsorbed FFA, was dried in a vacuum applied to the column
outlet for a few seconds, and then transferred to a
screw-capped test tube ( 12mm x 125mm). Five mL of 6%
formic acid in Nazsordried diisopropyl ether (v/v) were
added to the eluted FFA, followed by mixing and
centrifugation at 700xg for 5 min. Fatty acids were
analyzed with a gas chromatograph (Model 5840A , Hewlett
Packard, Avondal, PA) equipped with a flame ionization

detector. A glass column ( 2mmx3mm, ID ) packed with 10%

SP-Z]
Belle
acid:
min,

temp
dete
res;

was

com;

aci

Co
Qu
tr

C}

40
SP-216-PS ON 100/120 Supelcoport (Supelco, Inc.,
Bellefonte. PA.) was used for the separation of the fatty
acids. The GC oven temperature was held at 100°C for 10
min, then increased at a rate of 3.0°C/min to a final
temperature of 190°C and held for 30 min. The injector and
detector temperatures were held at 225°C and 275°C,
respectively. The flow rate of the nitrogen carrier -gas
was 25 mL/min.

Identification of the fatty acid was based on
comparison of retention times of samples to those of fatty
acid standards prepared in diisopropyl ether containing 4%
formic acid. Fatty acid distribution for each fraction was
based on integration of peak areas (HP-5840A GC Terminal
Integrator). To determine the influence of the cheese on
FFA recovery, known weights of synthetic FFA mixtures of
C:4, C:6, C:8, C:10, 0:12, C:14, C:16, C:18:0, C:18:l,
C:18:3 were added to cheese sample and extracted as outlined
above. Correction factors were obtained for C:4 to C:6
compared to C:7 and for C:10 to C:18:3 compared to C:17.
Quantitation method and response factors were the same as
those described by Deeth et al. ( 1983 ). All solvents and

chemical were of analytical grade.

9912:

Cheese color was evaluated with a color-difference
meter ( Hunter Lab, Model D 25-2). The instrument was

standardized against a white standard C2-12400.

Sam

and

co]
Un

Ca

pr
te
SE

VIE

41
Samples were placed in a cup covered with the glass plate

and readings were taken in triplicate.

WW;

Textural properties of cheese such as hardness,
cohesiveness and adhesiveness were measured with the Instron
Universal Testing Machine, Table Model 4202 (Instron Co.,
Canton, MA.) following the procedure of Bourne et al.
(1967,1968). Fresh and ripened cheeses were tempered at 5%:
iJPC for 12 hr. Samples were cut into 1.5 cm cubes just
prior to evaluation. The instrument was operated at room
temperature with a crosshead speed of 20 mm/min and a chart
speed of 76 cm/min. Full scale load was 50 N, and samples
were compressed to 75 % of their initial height. Each
sample was compressed twice by the compression load cell.
The textural evaluation was done in quadruplicate on each
batch of cheese. Areas under the response plot were
determined by a Planimeter (Keuffel-Esser) . The A1and
A2(cmz) represent areas under the curves formed during the
first and second compression cycles and represent work done
during compression. The height of the first peak during the
first bite represented the extent of hardness ( force )
while the distance of the sample under compression during
the second bite represented the springiness ( cm ).

Cohesiveness was derived from the ratio of Az/A1 whereas the

ch

of

Th4

of

42
gumminess was equal to hardness x cohesiveness and the
chewiness was equal to gumminess x springiness. The height

of A3 represented the adhesiveness.

W

The effect of ultrafiltration process on cheese
production were analyzed using the analysis of variance
(ANOVA), mean separation, and correlation subprograms of the
MSTAT Microcomputer Statistical Program ( ver. 4C, 1989).
The statistical analyses were performed on the mean values

of the duplicates for each replication.

RESULTS AND DISCUSSION

RARE-I

ULTRAI'ILTRATION 9mm STUD!

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W

Although the interest in the application of
‘ultrafiltration and diafiltration to food systems continued
'to increase, yet more information is needed on the changes
in composition of whole milk, skim milk and whey before

these membrane processes can find wide use in the food

industry. The purpose of this part was to study the effects
of pilot plant scale ultrafiltration on the retention of
milk and whey components, especially the minerals, nitrogen

fractions, amino acids, fatty acids, total solids, fat, ash

and lactose .

ML!
The permeation rate for whole milk, skim milk and whey

was studied using ultrafiltration and diafiltration
processes. Flux rate versus the amount of permeate removed
is shown in Figures 2 and 3. A gradual decrease in the

flux rate of whole milk was observed as the concentration

increased through stages of the UP and DF process. Yan et

31- ( 1979 ) reported a decrease in flux rate with increasing

c°ncentration of whole milk. As protein and fat were
concentrated in the retentate, the viscosity increased as

well as the development of a secondary membrane followed by

a decrease in

45

46

 

e—ODF
e--e UF

   

e§

\\<3\,

Flux Rate (L/mz/hr)

O

 

AAA.‘AAA.LAAA‘AA‘LI‘!LL.A‘AA._A_AAALALAA1AAL‘1AAA..AAM‘L‘A‘A

o 10 20 so 40 so so 70 so eatoonouo
Permeate Removed (x of whole milk)

Figure 2. Flux rate of whole milk during ultrafiltration

and diafiltration. A and B represent diafiltration start and
stop, respectively.

47
diffusivity . Thus, concentration became a limiting factor
of the UF process. Diafiltration was employed to purify the
protein to a greater degree and to reduce lactose and ash in
the retentate. The data in Figure 2 indicate that during
the UP of whole milk the flux decreased from 36.9 to 5.9
lymfi/hr with the permeate accounting for 80.3% of the milk.
The drop in flux represents the practical limitation of UF
when used for the production of pre-cheese retentate. The
same trend was observed when diafiltration was applied to
whole milk (until the point of adding deionized water). The
effect of "washing out" the lactose increase the flux from
19 to 25 L/mz/hr, followed by a reduction to 5.9 L/mz/hr.
Typical data comparing the permeation rate of whole milk,
skim milk and whey during UF, as previously described, are
plotted in Figure 3. For all materials, the flux decreased
as the process continued. The initial flux for whey, skim
milk and whole milk was 78, 50, 36.9 lymfi/hr, respectively..
The UF process stopped when the flux for whey, skim and
whole milk was reduced to 27, 18.3 and 9.12 L/mz/hr,
respectively.

Fenton-May et al. ( 1971 ) and Besik et a1. ( 1971 )
stated that permeation rates are directly proportional to
Reynolds number (RE) and inversely proportional to the
viscosity of the solution. Consequently, as the

concentration increased, the viscosity also increased

.L_.,

n .E\NE\-._ \ atom knew

 

flux Rate ( L/mZ/hr )

48

 

 

 

 

 

100 —
°° AWhey .
so OSkIm Milk
‘Whole mnlk

7a A
60
50
‘0 \

+ . A
20 \\.
'0 .e.

 

O

otozoaowsoco'mooootoo

Permeate Removed ( x of milk )

Figure 3. Relationship of flux rate to volume of permeate
of whole milk, skim milk and whey obtained during
ultrafiltration.

wh
fl
di
pe
wt

pi

49
whereas the RE values decreased. Thus, the variation in the
flux of whole milk, skimmilk and whey is related to the
differences in total solid, protein and fat contents. The
permeate flux of UP skimmilk was higher than that for UF
whole milk. Peri et al.( 1973 ) reported that the
permeation rate during UF of skim milk was inhibited by the
increasing concentration of lactose, protein and other
solutes. Starting flux for whey was higher than that for
skimmilk and whole milk because whey contains less protein
and fat ( Glover et al., 1978 ). The type of milk coagulant
used in cheese manufacture may influence the subsequent
permeate flux. The amount of permeate removed during UP and
DF processes is recorded in Tables 4A, 4B, 4C, 4D, appendix
4. The influence of protein and fat concentration on
permeation rates during ultrafiltration and reverse osmosis
of whey and skim milk is well documented in the literature.
Fenton-May et al.( 1971 ) reported that the flux rate was
controlled by the thickness of the protein and fat deposit
on the membrane surface. Also, the calcium ion
concentration, the formation of calcium phosphate gels, and
the ionic strength of whey directly influence the

ultrafiltration permeation rate of whey.

50

W

Mass balance was determined for ultrafiltration and
diafiltration processes ( Table 1 ). These data illustrates
the recovery of total solids and mass from whey, whole milk
and skim milk processed by ultrafiltration and
diafiltration. Recoveries were not quantitative in all cases
and ranged from 94.0 % to 99.4 % for total solids and from
91.7% to 96.0% for the mass. The recovery of total solids
from whole milk was higher by ultrafiltration (98.3%) than
by diafiltration (94.1 %). These results agreed with the
data reported by Covacevich and Kosikowski ( 1977b ) who
explained the difference between ultrafiltration and
diafiltration on the basis of greater protein purification,
and the interactions of flux, RE , protein content and
viscosity. Higher retentate viscosities encountered in
diafiltration experiments presented difficulties in draining
the retentate from the ultrafiltration apparatus. This
difficulty resulted in lower recoveries than did direct
ultrafiltration. Higher recoveries of total solids and mass
were obtained from whey and skim milk than obtained for

whole milk by ultrafiltration and or diafiltration.

51

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52

W

Gross changes in composition of the retentate of whole
milk, skim milk and whey obtained by direct ultrafiltration
and diafiltration processes are presented in Figures 4, 5, 6
and 7. Ultrafiltration of whole milk yielded retentate
with an average total solid content of 38.4 % , fat 16.5 %,
protein 10.5 %, lactose 7.9 % and an ash of 3.5 for three
trials after 80.3 % of the original product was removed as
permeate ( Figure 4 ). For concentrating protein to a
greater degree and reducing lactose and ash in the
retentate, diafiltration was employed. The compositional
changes of whole milk during the diafiltration process are
depicted in ( Figure 5 ). It shows that the retentate had
an average composition of 32.6 % total solid , 15.5% fat,
13.65 % protein, 1.9 % lactose and 1.5 % ash for three
replicates in which 113 % of permeate was removed. More
lactose and salts are removed by diafiltration than by
ultrafiltration. Flux limitations were encountered at lower
levels of total solids (32.6 %) for diafiltration than for
ultrafiltration (38.4%). These results are in agreement
with the data reported by Covacevich and Kosikowski (1977b).

The data presented in Table 2 illustrate that the
effects of diafiltration as compared to ultrafiltration on
the composition of retentate were primarily a reduction in
lactose and ash levels from 18.9% and 8.7% to 6.0% and 4.3%

(on dry weight basis), respectively, and an increase in

Away acoucoo

Content ( x)

53

 

  
    
 

 

 

 

 

 

so _
45 O—O'l'otol solids
o—OFot
4o A—ALoctose
A—A Protein
35 e—eAsh
30 /
25 O
20 /
15 do
‘0 o/ ‘
5 4
o ....... lAb—AIAALA‘ALLAtAA.ALAA.AAAA.AAA

o 10 20 so 40 so so 70 so so 100
Permeate Removed ( x of milk )

Figure 4. Composition changes in whole milk retentate
during ultrafiltration.

Ax“ v accucoo

54

 

50‘

45 o—OTotol solids
O-—O F at

40 a—a Protein
A—A Lactose

35 4n-MDASh

3° . ,/
2. /'\f/./

Content ( x )
N
U.

 

10 '\.
. §F===EF—"""
5.. k
‘ O—A ‘

 

 

 

0 cu“ 2mm“ 1'- o-nr- m

0 1O 20 3O 4O 50 60 7O 80 90 100 110 120

Permeate Removed ( x of milk )

Figure 5. Composition changes in whole milk retentate during
diafiltration. A and B represent diafiltration start and

stop, respectively.

 

‘19:.

55

Table 2. Dry matter composition of whole milk,skimmilk and
whey retentate obtained by ultrafiltration or
diafiltration

 

Content (%)

 

 

Fluids Protein Lactose Ash Fat
Whole milk (UF) 26.6 18.4 8.7 43.3
Whole milk (or) 42.0 6.0 4.3 47.4
Skim milk (UF) 51.5 35.5 13.9 ND
Whey (UF) 45.3 44.7 10.0 ND

 

The data represent average of three determinations.

ND- not detectable.

56

protein content from 26.6% to 42% (on dry weight basis) in
the final retentate. Such differences in composition were
also observed by Brown ( 1986 ). Figures 6 and 7 depict
the change in skim milk and whey retentate induced by the
ultrafiltration process. The data reveal a pattern similar
to that of ultrafiltrate whole milk using UF ( Figure 4 ).
A large increase in individual components was observed when
about 82 % of the permeate was removed for producing a whey
protein concentrate (WPC) with 15.7 % total solid, 7.1 %
protein, 7% lactose and 1.6 % ash and a concentrated skim
milk was made with 19.5 % total solid, 10.0 % protein, 6.9 %
lactose and 2.6 % ash content. The higher recovery of total
solid from whole milk than from skim milk may due to the
essentially complete retention of fat ( Glover, 1971: Green
et al., 1984 ). Both products showed similar lactose and
ash contents and a high degree of protein retention
( Table 2 ), a relationship also noted by Glover ( 1971 ),
Bundgaard et al.( 1972 ), and Green ( 1984 ).

The data presented in Tables 5A, SB, 5C, 5D ( Appendix
5) show the volume concentration ratio (VCR) as determined
periodically during ultrafiltration and diafiltration.
there was an increase in the VCR of whole milk ,skim milk
and whey which was higher for whey than for milk. This
observation reflects a greater volume reduction of whey.
Also, the ultrafiltration retentate possessed a higher VCR
than the diafiltration retentate as a result of greater

retention of fat, lactose and ash in the former.

 

57

 

IV

O— O Total solids
A — a Protein

A — A Lactose
O— 0 Ash

'j'

 

 

 

 

01020'304050507030‘90100

Permeate Removed ( x of milk )

Figure 6. Composition changes in skim milk retentate during
ultrafiltration.

I a \ illi‘lq‘l.‘

58

 

O—eTotal solids
A—A Protein
A — A Lactose

A“ . O—OAsh /

d
D
' V fv

(
033
I‘UfUri

 

 

 

  

F

o 10 20 30 4o 50 so 70 so so 100
Permeate Removed ( x of milk )

Figure 7. Composition changes in sweet whey retentate
during ultrafiltration.

59
By comparing the VCR of the final retentate obtained by
ultrafiltration and diafiltration with the concentration
factor (CF) for each constituent ( Tables 5A and 5B,
Appendix 5 ), it was found that the fat was equal to or
close to the value expected from the amount of permeate
removed. These values indicate that fat was completely
retained by the membrane which was confirmed by the analysis
for fat in the permeate. Conversely, the protein content
was less than expected from the amount of permeate removed,
indicating that some of the protein passed with the

permeate and some were retained in the ultrafiltration unit.

mam-9211112:
The effect of ultrafiltration and/or diafiltration on

the compositional characteristics of whole milk permeate is
indicated by data plotted in Figures 8 and 9. These graphs
reveal a complete recovery of fat in the ultrafiltration
and diafiltration retentate, confirming the findings of
Ernstrom et al. ( 1980 ). They have reported that rejection
of fat during ultrafiltration was complete while a small
loss of nitrogenous fraction occurred in the permeate,
consisting primarily of non-protein nitrogen (NPN).

Barbano et al. ( 1988 ) reported that the NPN content did
not increase in the retentate because most of it passed

through the membrane, mainly in the form of urea.

Content ( X)

9

d

O

60

 

O— O Total solids _
A— A PFOtSifl .

A—A Lactose ,A
O—O Ash /

A #47

 

 

 

 

 

 

i
it
no

a
O
o
o
.e
3

 

7O

8
8
8
8

20

0
d
O

Permeate Removed ( x of milk )

Figure 8. Composition changes in whole milk permeate during
ultrafiltration.

61

 

a
A o—OTotal solids
7 a—a Protein
A— A Lactose
A ‘ fl ._....
3 5 a/
a
c .
.3 4.
5
o

N

d

  

 

 

 

 

e

10 20 30 4O 50 60 70 SO 90 100 110 120

Permeate Removed ( X of milk )

Figure 9. Composition changes in whole milk permeate during
diafiltration. A and B represent diafiltration start and

stop, respectively.

 

stud:
nitri
and a
agrei
chara
founc
prot.
perm:
lact«
of d
soli
in F
cons
addi
Tabl
that
(0.2
i).

Fret
Corr
Coto‘
ultr
“0th;
skim
resp‘

solil

62

Based on the protein analysis and electrophoretic
studies of the final permeate, it can be concluded that the
nitrogen fraction found in the permeate was composed of NPN
and a small amount of a-lactalbumin. This observation
agrees with the finding of Barbano et al. ( 1988 ), who
characterized the ultrafiltrated permeate by SDS-PAGE and
found that a-lactalbumin composed 90 % of the permeate
protein. Ultrafiltration produced a final whole milk
permeate with a composition of 7.4% total solids, 6.5 %
lactose, 0.4 % protein and 0.5 % ash. While the composition
of diafiltration whole milk permeate consisted of 3% total
solid, 2.4 % lactose, 0.2 % protein and 0.4 % ash. As shown
in Figures 8 and 9, the high content of permeate
constituents was more pronounced with UF than DF due to
adding water and lower lactose content. As presented in
Tables 6A, 6B, Appendix 6, the average calculation indicated
that percentage loss of protein in the permeate was higher
(0.22 %) for ultrafiltration than for diafiltration (0.13
%). As stated by Ernstrom et al.( 1980 ) the rate of
protein loss varied through the process and appeared to be
correlated to the protein concentration in the retentate.
Coton ( 1980 ) stated that most of the nitrogen content of
ultrafiltrated permeate from milk was NPN material
normally found in milk. The average permeate composition of
skim milk and whey is recorded in Table 3 and 4,
respectively. The data indicate that the high level of

solids in the permeates consist primarily of lactose and

63

Table 3. Permeate composition of ultrafiltrated skim milk

Composition (%)

Total solid

Ash Lactose NCN NPN

0.83 4.76 0.35

NCN-non-casein nitrogen, NPNsnon-protein nitrogen, a-La
(a-lactalbumin) equals to NCN-NPN.

The data are the average of three determinations and
presented by (%Nx6.38 ).

Table 4. Permeate composition of ultrafiltrated whey

Composition (%)

Total solids Ash Lactose NCN NPN

NCN-non-casein nitrogen, NPN-non-protein nitrogen, a-La
(a-lactalbumin) equal to NCN-NPN.

The data are the average of three determinations and
presented by (%Nx6.38 ).

64
minerals, accompanied by a small amount of NPN and
a-lactalbumin. This incomplete rejection of protein may be
due to distribution of pore size in the membrane and/ or the
configuration of the protein under these processing
conditions. .Also, Barbano et al.( 1988 ) attributed the
passage of protein through an ultrafiltration membrane to
protein molecular weight plus other protein characteristics
such as charge, hydrodynamic size, shape and hydrophobic or
hydrophilic character. The nature of the foulant material
adsorbed on the UP membrane surface may also effect the

passage of protein in the membrane.

Was
The effect of ultrafiltration and diafiltration on the

nitrogen distribution of whole milk, skim milk and whey was
investigated. The data obtained from the nitrogen analyses
are presented in Table 5 through 8. The data reveal a
gradual increase in total nitrogen, casein, non-casein and
total albumin level in the retentate as a result of UP and
FD processing. Most of this increase was due to the
retention of casein and total-albumin, especially
fi-lactoglobulin, with a little increase in the non-protein
nitrogen. Matthews et al. ( 1976 ) and Clover et al.

( 1979 ) reported that the percentage of NPN in milk
retentates did not increase with concentration because a
portion of the original milk NPN ( mainly urea, amino acid

and ammonia ) freely passed through the membranes.

65

Table 5. Change in the nitrogen distribution of whole milk
during ultrafiltration

 

Volume Concentration Nitrogen Fractionsa

 

 

Ratio ( % )
(VCR)
TN CN NCN TA NPN

1.0 3.25 2.49 0.76 0.00 0.15
1.14 4.04 2.90 1.14 0.90 0.16
1.5 4.90 3.50 1.40 1.20 0.16
2.5 7.17 5.48 1.69 1.40 0.16
4.1 9.32 7.10 2.22 1.85 0.17
4.8 10.50 8.00 2.50 2.20 0.18
CF 3.23 3.2 3.3 3.6 1.1

 

'Protein concentrations (%Nx6.38 ) as the average of three
determinations.
CF- Concentration Factor at.conclusion of UP is the ratio
of final protein in retentate to the protein of original
product.
TN, CN, NCN, TA and NPN represent total nitrogen, casein,
non-casein nitrogen, total albumin nitrogen and non-
protein-nitrogen, respectively.

66
A comparison between the ultrafiltration and diafiltration
processes on the nitrogen distribution of whole milk is
presented in Tables 5 and 6. These data indicate that
diafiltrated retentates had greater protein concentration
than ultrafiltrated retentates. The nitrogen distribution
in diafiltration retentate was 13.65 % total nitrogen,
10.35% casein nitrogen, 3.3 % non-casein nitrogen, 2.2%
total albumin and 0.17 % non-protein nitrogen as compared to
10.5% , 8.0 % , 2.5 %, 2.2 % and 0.175 %, respectively, in
retentates from ultrafiltration . This difference may be
attributed to the effect of adding water during the
diafiltration process which causes an increase in
concentration and purification of the constituent proteins.
The protein content decreased upon initiation of
diafiltration due to dilution of the retentate. However,
it increased during the terminal stages of diafiltration as
a result of an increase in the permeation rate and due to
the amount of permeate removed (Table 6). When the volume
concentration ratio ( VCR ) was compared to the
concentration factor (CF) of the protein fraction, the
increase in protein concentration was not as high as
anticipated. The same was true in the case of
ultrafiltration processed products ( Tables 5, 7 - 8 ). A
possible explanation for this discrepancy is the retention
of a highly concentrated protein layer on the membrane in
the ultrafiltration unit which was not recovered in the

retentate. This connection was confirmed qualitatively by

67

Table 6. Change in the nitrogen distribution of whole milk
during diafiltration of whole milk

 

Volume Concentration Nitrogen componentsa

 

 

Ratio ( % )
(VCR)
TN CN NCN TA NPN
1.0 3.10 2.38 0.72 0.48 0.16
1.09 3.38 2.62 0.76 0.54 0.16
1.5 7.40 5.81 1.59 1.30 0.16
3.0 8.99 7.19 1.80 1.62 0.17
2.0 5.74 4.78 0.96 0.73 0.16
2.66 7.59 5.70 1.89 1.62 0.17
4.0 9.83 7.68 2.23 1.94 0.17
4.5 13.65 10.35 3.30 2.20 0.17
CF 4.4 4.3 4.5 4.5 1.06

 

'Protein concentration( N x 6.38 ) as average of three

determinations.

CFa Concentration Factor at conclusion of UP is the ratio
of final protein in retentate to the protein of original
product.

TN, CN, NCN, TA and NPN represent total nitrogen, casein,
non-casein nitrogen, total albumin,and non protein nitrogen
compounds, respectively.

obser
mater
shutd
surfa
reten
show

durin
durin
obser
conta
% NPN
0f wj
reten‘
remOVl
becau:
rennei
also a
the wt
diafi]
c°mPOs
inCreE

t° 7.:

 

fNet.

but n

68
observing the release of thin sheets of proteinaceous
material during the clean up step after the unit was
shutdown. The presence of this protein film on the membrane
surface caused a decrease in the flux and lower protein
retention ( Ernstrom et al.,1980 ). The data in Table 7
show the change in the nitrogen fractions of skim milk
during UP. The trend of increasing protein concentration
during ultrafiltration, that occurred with whole milk, was
observed with skim milk. The final skim milk retentate
contained 10 % TN ,7.55 % CN , 2.4 % NCN, 2.0 % TA and 0.17
% NPN. The data in Table 8 relating to the ultrafiltration
of whey indicate that the protein concentration of the
retentate increased directly with the amount of permeate
removed. There is more NCN present in whey than in the milk
because of the release of macropeptides by the action of
rennet on casein during the manufacture of cheese. There is
also a small, variable amount of casein ”fines" present in
the whey which is concentrated by ultrafiltration /or
diafiltration. As the data in Table 8 reveal, the
composition of the whey protein concentrate (WPC) was
increased from 1.12 % TN ,1.1 % NCN, 0.6 % TA and 0.5 % NPN
to 7.0 t , 6.3 t, 3.7 % and 0.6%, respectively. As
discussed in the earlier studies with milk, the membrane
permits free passage of the NPN fraction, while the TA
fraction, a-lactalbumin and fi-lactoglobulin are concentrated
but not to the same extent. The VCR of whey was higher than
the VCR of both whole milk and skim milk due to the

Table
ultra

 

Volun
Rati
(VCF

1.0
1.08
1.4

1.8

2.6

 

69

Table 7. Change of nitrogen distribution in the
ultrafiltration skim milk

 

Volume Concentration Nitrogen Components“

 

 

Ratio ( 3 )
(VCR)

TN CN NCN TA NPN
1.0 3.10 2.40 0.70 0.50 0.15
1.08 3.20 2.40 0.80 0.60 0.15
1.4 4.50 3.50 1.00 0.80 0.15
1.8 6.00 4.70 1.20 1.10 0.16
2.6 7.80 6.10 1.60 1.40 0.16
3.6 8.9 6.8 2.1 1.90 0.16
4.2 10.0 7.60 2.40 2.00 0.17
CF 3.2 3.15 3.5 3.6 1.15

 

'Protein concentration (%Nx6.38) as average of three

determinations.

CF- Concentration Factor at conclusion of UP is ratio of
final protein in retentate to the protein of original
product.

TN, CN, NCN, TA and NPN represent average of total
nitrogen, casein, non-casein nitrogen, total albumin and
non-protein nitrogen compounds, respectively.

Table
ultra

1.0

1.15

 

70

Table 8. Changes of nitrogen distribution in the
ultrafiltration whey

 

Volume Concentration Nitrogen componentsl

 

 

Ratio ( % )
(VCR)
TN NCN TA NPN

1.0 1.12 1.10 0.60 0.50
1.15 1.34 1.29 0.60 0.57
1.5 1.78 1.70 1.00 0.57
2.6 2.60 2.40 1.70 0.57
4.4 5.00 4.60 3.00 0.58
6.2 7.00 6.30 3.70 0.60
CF 6.2 5.7 6.1 1.2

 

IProtein concentration (%Nx6.38 ) as average of three
determination.

CF- Concentration factor at conclusion of UP is ratio of
final protein in retentate to the protein of original
product.

TN, NCN, TA and NPN represent mean of total protein,
non-casein protein, total albumin and non-protein nitrogen
compounds, respectively.

inc
dem
can
Dia
tha:
pro’
not
ratj

proc

71
increased quantities of permeate removed. These results
demonstrate that ultrafiltration and diafiltration processes
can be used to concentrate constituent protein fractions.
Diafiltration permits higher levels of protein concentration
than does direct ultrafiltration. However, recovery of
protein, as estimated from the concentration factor, was
not the same as estimated from the volume concentration
ratio. This was especially true for ultrafiltration

process.

W

Nineteen mineral elements of whole milk, skim milk and
whey and of their respective retentates and permeates were
assayed to ascertain the potential contribution of these
nutrients to the nutritional value of foods in which they
are utilized, especially for milk designated for
cheesemaking. The concentration of major and trace minerals
in the final retentate and permeate of ultrafiltrated sweet
whey is presented in Tables 9 and 10. Higher levels of Ca,
P, Mg, Zn, Fe and Cu were observed in the retentate than in
the permeate. The remaining minerals showed no definite
difference. Since all or a major portion of these elements
are associated with proteins they are expected to be
retained during the ultrafiltration process. The percent
retention of each mineral ( Table 9, 10 ) decreased in the

order: Ca 2.3) P 2.1> Hg 1.6> Zn 1.4> K 1.3 > Fe 1.3. When

Tabl
and

Sweet
Reten

Perms
CF

.Avera
CF: Cc
final
Pl'Odm

 

72

Table 9. Major mineral content of sweet whey, retentate

and permeate using ultrafiltration'

 

 

 

 

Ca Hg Na K P
mg/100g
Sweet whey 34.4 6.1 47.8 123 45.4
Retentate 79.2 10.0 53.2 160 95.3
Permeate 41.3 7.1 60.0 157 46.8
C? 2.3 1.6 1.1 1.3 2.1

 

'Average of three determinations.

CF- Concentration factor at conclusion of UP is ratio of

final protein in retentate to the protein of original

product.

Ta
co

Swe
Rat:
Per:
CF
AVe:
CF:
fina.

Pr0d1
ND :1

73

Table 10. Trace mineral composition of sweet whey,
concentrate and permeate using ultrafiltration

 

 

 

 

Zn Fe Cu B Mn Mo Ba

#9/1009
Sweet whey 19 90 7.2 5.1 1.9 NDA NDA
Retentate 26 120 19 1.5 1.7 0.36 0.2
Permeate 26 60 6.1 6.4 3.0 3.0 1.9
or 1.4 1.33 2.6 0.29 0.89 ND ' ND

 

'Average of three determinations.

CFa Concentration factor at conclusion of UP is ratio of
final protein in retentate to the protein of original
product.

ND -not detectable.

com;

for

repl

Howe

higt
coul
mine
prod
lact
mine
in T.
Na, 1
in t]
at a]
with
nine:
casej
with
Casej
fath
Jenna
the h
Table
the r
facto
rate”

Milk

74
compared with the published data for liquid whey, the values
for the major minerals were almost identical with those
reported by Wong et al.( 1978 ) and Feeley et al.( 1972 ).
However, the values for Cu, Mn, 8, Mo, and Ba were somewhat
higher than reported by those researchers. This discrepancy
could be due to several factors which may influence the
mineral content of whey, including the type of cheese being
produced, the geographic area, source of milk, stage of
lactation and processes employed. The major and trace
minerals of whole milk retentate and permeates are tabulated
in Tables 11 and 12. Generally, the content of Ca, P, Mg,
Na, K, Zn, Fe, Cu and B were higher in the retentates than
in the permeates. These results are in agrement with Brule
et al.( 1974 ) who stated that calcium increased linearly
with CF in milk retentate, and constant in permeate. These
minerals have been shown to be partially associated with
casein micelles and the fat globule membrane and retained
with the protein concentrate. The amount relative to
casein usually decreased with increase in the concentration
factor, reported by Green et al.( 1984 ), and Walstra and
Jenness ( 1984 ). The higher the protein concentration,
the higher was the colloidal Ca. The data presented in
Table 11 and 12 indicate that the minerals concentrated in
the retentate were in order of decreasing concentration
factors: Ca 4.1; P 3.2; Zn 2.4; Mg 2.1: Fe 1.8. The high
retention of Zn and Fe during the ultrafiltration of whole

milk was also observed by Fukuwatari et al.

ret:

 

75

Table 11. Major mineral content of fresh whole milk,
retentate and permeate by diafiltration

 

 

 

 

Ca Mg Na K P
m9/100 9
Fresh 110 9.7 47.9 200 98.6
Retentate 450 20.1 35.6 250 310
Permeate 32.9 6.59 46.15 107 42.4
CF 4.1 2.1 0.74 1.3 3.2

 

'Average of three determinations.

CF- Concentration factor at conclusion of UF is ratio of
final protein in retentate to the protein of original
product.

Table
reter

 

76

Table 12. Trace mineral composition of whole milk,

retentate and permeate by diafiltration

 

 

 

 

Zn Fe Cu B Ba Mn Mo

#9/1009
Milk 390 50 8.0 17 NDA 5.0 5.8
Retentate 940 90 5.0 6.0 0.6 4.3 '3.8
Permeate 410 49 13.0 7.9 ND 0.9 2.0
CF 2.4 1.8 0.63 0.35 0.0 0.86 0.66

 

'Average of three determinations.

CF- Concentration factor at conclusion of UP is ratio of
final protein in retentate to the protein of original

product.
ND- not detectable.

Tabl
rete

I I

skim
Retex

Perm.
CF

AVer‘
CF: C
final
prOdu

 

77

Table 13. Major mineral content of fresh skim milk,
retentate and permeate by ultrafiltration

 

 

 

 

Ca Mg Na K P

mg/100g
Skim milk 125 10.8 48.1 160 180
Retentate 400 16.6 40.8 300 410
Permeate 53 9.0 40.0 110 85
CF 3.2 1.5 0.84 1.9 2.3

 

9Average of three determinations.

CF- Concentration factor at conclusion of UP is ratio of
final protein in retentate to the protein of original
product.

Tablel
reten‘

Skin
Reta
Perm

CF

 

 

Table 14.

retentate and permeate by ultrafiltration

78

Trace mineral composition in fresh skim milk,

 

 

 

 

Zn Fe Cu 8 Ma
ug/100g
Skim milk 420 62 8.2 15.0 3.5
Retentate 840 70 15.0 8.0 4.6
Permeate 390 30 3.1 1.5 0.5
CF 2.0 1.13 1.8 0.5 1.3

 

'Average of three determinations.
CF- Concentration factor at conclusion of UF is ratio of

final protein in retentate to the protein of original

product.

( 1

cas
Fe,

198
ski]
per]
14
ultl
expe
mil}
simj

more

Ofw
EIEC

ultr

'hOIe

Drot

its

 

ultr-
12

79
( 1982 ). The retention of Na and trace minerals was low in
the retentate. Enzymes, including those associated with
casein micelles and milk fat globule membrane, contain Mo,
Fe, Cu, P and Zn ( Webb et al., 1974: Walstra and Jenness,
1984 ). This Content of the major and trace minerals in the
skim milk and their distribution between retentate and
permeate were similar to those of whole milk ( Table 13 and
14 ). Since macromolecules were retained during
ultrafiltration, high recoveries of associated minerals were
expected even though the retention varied a little from one
milk to an other. In general all the products showed
similar mineral levels as a result of UF processing, with

more retention in retentate than permeate.

W
The effect of ultrafiltration on the protein fractions

of whole milk, skim milk and whey was studied
electrophoretically at the beginning, middle and end of the

ultrafiltration run.

whole Milk

A typical densitometer tracing for separation of
protein in the whole milk, its casein (Cn) fraction , and
its total albumin (TA) fraction at different stages of the
ultrafiltration process are presented in Figures 10, 11 and

12, respectively. Peaks were identified from the protein

 

 

 

1"191.11% 10. Discontinuous polyacrylamide gel electrophoresis
densitograms of whole milk retentate. A; a-casein 8: #-
la<=1zoglobulin & B-casein, c: a-lactalbumin. Ultrafiltration
*- llle: 1: 0.0 min; 2: 30 min: 3: 60 min.

80

 

 

 

 

a My...

M

Figure 11. Discontinuous polyacrylamide ge1 electrophoresis
densitograms for casein of whole mi1k retentate. A: a -casein

B: fl-casein. Ultrafiltration time: 1: 0.0 min: 2: 30"min: 3:
60 min.

 

 

 

 

 

81

densit
lactog

 

82

LL

Figure 12. Discontinuous polyacrylamide gel electrophoresis
densitograms for total albumin nitrogen of whole milk
retentate. A :c-lactalbumin, 8: n-lactoglobulin B, C :8-
lactogfibulin A. Ultrafiltration time: 1: 0.0 min: 2: 30 min:
= 60 n.

83
standards of a-casein, fi-casein, a-lactalbumin and 8-
lactoglobulin. The pattern illustrates that there was
substantial increase in component peak areas corresponding
roughly to the degree of concentration achieved by
ultrafiltration. Representative protein profiles for whole
milk are shown in Figure 10. Areas under peaks A, a;-
casein (c.Cn): B, B-casein and fi-Lactoglobulin (fi-Cn and
8-Lg ) and C, a-lactalbumin (a-La) increased with the
duration of ultrafiltration, i.e., corresponding roughly to
the extent of concentration (Table 8A, whole milk, Appendix
8). As the minor peaks were not identified, they were not
used in the computation. The identified bands from whole
milk were similar to that bands which extracted for casein
and total albumin nitrogen from same whole milk. Figure 11
represents a typical densitometric tracing of the total
albumin nitrogen (TAN) fraction of the whole milk. The B
and C peaks represent fi-lactoglobulin. In Figure 12, the
peak areas under A, B and C were increased with the duration
of ultrafiltration. The data in Table 8A for TAN ( Appendix
8) reveal that the dominant component of TAN is to p-Lg (A
and B), ranging from 77.5% to 83.8 % , whereas a-La ranged
from 22.4% to 16.2 t. The ratio between a-La and fi-Lg
changed with processing time due to the release of a-La
through the UP membrane. This relation was confirmed by
fractional analysis of the retentate and by the nitrogen
determination of the permeate. Figure 12 represent a

typical pattern derived from the casein fraction of whole

 

 

00

 

 

 

 

m'

Figure 13. Discontinuous polyacrylamide gel electrophoresis
densitograms for casein of skim milk retentate. A: afl-casein
B; fi-casein. Ultrafiltration time: 1: 0.0 min: 2: 30 min: 3:
60 min.

84

85

B
c
A

3

c313
2 A

<33
1 A

Figure 14. Discontinuous polyacrylamide gel electrophoresis
densitograms for total albumin nitrogen of skim milk
retentate. A :a-lactalbumin, B :8-lactoglobulin B, c :p-
lactoglobulin.A. Ultrafiltration time: 1: 0.0 min: 2: 30 min:

3: 60 min.

86
milk. Areas under peak A, a.-Cn and B, (fi-Cn) indicate a
noticeable increase with concentration. Calculations
(Table 8A, Appendix 8 ) indicate that the relative increase
in a-Casein and fi-Casein was constant throughout the
ultrafiltration process. It is also apparent that milk
proteins were concentrated during ultrafiltration but with a

little less of a-lactalbumin.

Ski-.milk

Typical densitometer tracings which illustrate the
separation of proteins in the casein and TAN fractions of
skim milk and its retentate obtained during UF processing,
are presented in Figures 13 and 14. The PAGE pattern of
casein and TAN in skim milk and their relative distribution
were similar to those observed in the case of whole milk

( Table 88, Appendix 8 ).

whey

A typical densitometer tracing for the separation of
a-La and fi-lg, the principal fraction of (TAN) in the sweet
whey, is presented in Figure 15.

A comparison of whey and concentrated whey obtained at
different ultrafiltration processing times indicates
increasing peak area with concentration. Area under peaks
A and 8 represents the relative amount of a-La and 8- Lg,

respectively. The larger fraction of TAN was attributed to

87

ijarul

 

 

 

 

Figure 15. Discontinuous polyacrylamide gel electrophoresis
densitograms of whey retentate. A :c-lactalbumin, B :p-
lactoglobulin A and p-lactoglobulin 8. Ultrafiltration time:
1: 0.0 min: 2: 15 min: 3: 30 min: 4 :60 min.

88
B-Lg, ranging from 76% to 90.2 % , whereas a-La ranged
from 24% to 9.8 %. The distribution between both
components changed as a result of increased concentration,
but not in the same ratio ( Table 8C, Appendix 8). These
observations indicated that either the ultrafiltration
membrane permitted molecules greater than 5,000 Daltons to
pass through or the conformational characteristics of a-La
(14,200 Daltons ) allowed its passage through the membrane.
Also, the release of a-La may be due to the age of the
membrane used in this process. These results were within
same limits previously reported by Lee and Merson ( 1974 )

and Barbano et al.( 1988 ).

W
Whey protein is a highly nutritious by-product of

cheese. The whey represent the non—casein protein as well
as the fractions and fragments of the casein which remain
soluble when casein have been precipitate. Total amino acid
content of sweet whey obtained from a manufacture of
Egyptian Domiati cheese and its concentrated protein
obtained by ultrafiltration was analyzed by HPLC. The

- pattern of seventeen amino acid is presented in Table 15.
The data revealed a large increase in the total amino acids
from 115.8 to 453.36 mg/g of dry matter resulting from
ultrafiltration. The increase of individual essential and

nonessential amino acid residuals was consistent and

89

Table 15. Total amino acid contents of sweet whey and whey
protein concentrate

 

Whey WPC
Amino Acids Fold Increase

mg/q (dry weight)

 

Essential_ala
Histidine 2.3 8.2 3.6
Threonine 7.7 33.2 4.3
Valine 8.0 33.6 4.2
Isoleucine 8.8 36.9 4.2
Leucine 13.0 55.6 4.2
Phenylalanine 3.4 17.0 4.1
Lysine 10.8 50.2 4.6
Methionine 3.3 10.5 3.2
Cystine 2.5 6.2 2.5

Hsnessentlallhla
Aspartic acid 7.4 25 3.4
Glutamic acid 18.9 69.5 3.6
Serine 5.9 24.3 4.1
Glycine 3.0 12.2 4.0
Arginine 4.5 16.8 3.7
Alanine 8.3 27.0 3.3
proline 4.0 13.7 3.4
Tyrosine 3.8 13.2 3.5

IQS:1_A‘A 115.8 453.3 3.9

 

WPCa Whey Protein Concentrate.
The data are averages of three determinations.

90
ranged from 2.5-fold to 4.6-fold of that present in whey. A
low concentration of sulfur amino acids ( cystine and
methionine ) was detected probably due to destruction during
the analysis. The results showed that whey protein
concentrate (WPC) is a very good source of amino acids
reflecting the presence of a-lactalbumin and fl-
lactoglobulin in the retentate. This observation was
previously reported by Wingerd ( 1971 ) and Hambraeus (1982)
who stated that whey protein concentrate is a superior
source of essential and nonessential amino acids and could

be an excellent supplement for processed foods.

W
The separation and quantification of free fatty acids

of whole milk and retentate was achieved by GC on a
SP-216-PS column. The results are presented in Table 16.
The data revealed an increase in the total free fatty acids
from 33.7 to 80.1 mg /100 9 when whole milk was concentrated
by ultrafiltration. The total increase of 2.38-fold in FFA
was compatible with the increase in fat content in the
retentate ( Tables 5 and 6 in appendix 7 )

Individual fatty acids increased consistently from 2 to
3-fold except the short chain fatty acids ( C:4 and C:6 ).
High temperature (50°C) used during ultrafiltration may have
resulted in the volatilization of short chain fatty acids.

91

 

 

 

Table 16. Free fatty acid composition of whole milk and
retentate
Fatty acid Milk Retentate Concentration
factor
mg/100g
C4:0 1.5 1.6 1.1
C6:0 1.0 1.6 1.6
C8:O 0.6 1.4 2.0
C10:0 1.2 2.7 2.3
C12:0 1.6 3.5 2.2
C14:0 2.8 7.1 2.5
016:0 10.4 25.5 2.5
C18:0 3.5 10.0 2.9
C18:l 8.5 21.0 2.5
C18:2 1.5 3.6 2.4
C18:3 1.1 2.2 2.0
IQ§§1_E‘£‘A 33.7 80.1

 

The data are averages of three determinations

92
However, adding water during the diafiltration step could
also wash out some of the soluble short chain fatty acid.

A typical chromatogram of the fatty acid retention time
is presented in Figure 7A ( Appendix 7 ). A recovery study
on the procedure and the correction factors for relating the
internal standards to the individual fatty acids measured
are presented in Table 7A, ( Appendix 7 ). The results for
milk fat, correction factor and recovery data agree
reasonably well with the results obtained by Deeth et al.(

1983 ).

em 11.

meme 0' noun: cause cam
Wlom m “MIMIC!
muons

W

Egyptian white, soft cheese ” Domiati" differs greatly
from other cheese varieties by having its milk highly salted
before renneting ( Fahmi and Sharara, 1950 ).

Manufacture of Domiati cheese from ultrafiltration
retentate, using the concept of Maubois, Mocquot, and Vassal
(MMV) in 1969, saved several processing steps normally
required in conventional methods. The MMV technique
required only 10 min for curd formation, reduced the amount
of rennet used, eliminated the cutting and drainage process
(12-48 hr) and produced cheese higher in whey protein
content.

The objective of this phase of the experiment was to
compare fresh Domiati cheese made from ultrafiltration
retentate with cheese made from whole milk by a conventional

method.

W

Fresh whole milk was used to manufacture Domiati cheese
using the conventional method as outlined by Mahmmoud
( 1980 ). A portion of the same milk was ultrafiltrated to
produce the liquid pre-cheese (LPC) used to manufacture
Domiati cheese by the MMV technique. The composition of
whole milk and liquid pre-cheese is presented in Table 17.

94

Table 17.

95

The composition of whole milk and liquid pre-

cheese used for making Domiati cheese by conventional and

ultrafiltration methods

 

 

 

Composition Whole milk Liquid pre-cheese
mg/lOOg'
HQQDIfiD 8990350

Total solids 12.16iO.61 32.610.96
Fat 3.4110.21 15.510.64
Ash 0.7110.06 1.5:0.11
Lactose 4.7510.28 1.910.24
Protein 3.1910.22 13.711.10
Non-casein N 1.24:0.07 3.3:0.43
Non-protein N 0.2510.03 0.410.05
Total albumin N 0.75:0.09 2.2:0.16
PH 6.60iO.16 6.310.11

 

'Values are the means and standard deviations of three

replications.

Protein represented by (% N x 6.38).

96
The composition of fresh Domiati cheese obtained by the
conventional and ultrafiltration methods are presented in
Table 18. The data reveal only a slight difference in
composition between the cheese produced by the two methods.
The moisture was higher in ultrafiltrated milk-derived
cheese ( UF-cheese ) but the difference was not significant
at p< 0.05. Despite the fact that UF-cheese had a lower
total solids content ( 36.9 vs 38.1 % ), it contained a
higher total protein content which resulted from the
incorporation of whey protein ( Covacevich and Kosikowski,
1977b ). Cheese produced from ultrafiltrated milk had a pH
of 6.1 and acidity of 0.09 % which are significantly
different than corresponding values of pH 5.8 and 0.3 %
acidity respectively, for conventional cheese. These
differences could be attributed to the diafiltration step
which reduced the salt and lactose content in the liquid
pre-cheese concentrate. The net result is an increase in
the buffer capacity of the produced cheese
( Green et al., 1981 ). Salt and ash contents of
conventional and UF-cheese are not significantly different
at p< 0.05 ( Table 18 ).

Nitrogen determinations provided information about
differences in protein fractions of fresh Domiati cheese
made from ultrafiltrated milk and whole milk, see Table 19.
Nitrogen values for total protein, non-casein nitrogen,
total albumin nitrogen and soluble nitrogen (SN) fractions

of ultrafiltrate-derived cheese were significantly different

Table 18. The composition of fresh Domiati cheese made by

97

conventional and ultrafiltrated methods

 

 

 

Composition UF-cheese Conventional cheese
mq/g
Moisture 63.10' 61.90'
Fat 15.75' 18.00b
Ash 4.88' 4.56'
Protein 14.78' 13.07b
Salt 2.87' 2.80'
PM 6.10' 5.80”
Acidity 0.09' 0.30b

 

"Means within rows for each components with the same
superscripts are not significantly different (p < 0.05)
Protein represented by (%N x 6.38).

98
at p< 0.05 from the corresponding fractions of conventional
cheese. These results reflect the concentration of all the
whey protein in the UF-retentate. The non-casein nitrogen
(NCN) fraction of ultrafiltrate-cheese (4.09 %) contained
2.04 % of total albumin nitrogen (TAN), whereas the NCN
fraction of conventional cheese ( 1.47 % ) contained about
0.05 % of TAN. The data, also indicate that there was not a
highly significant difference of NPN between the two
cheeses. Koning et al.( 1981 ) stated that the production
of SN in UF-cheese is linearly correlated with the amount of
rennet used for the manufacture of the cheese.

The ratio of NCN/TP initially presented in the fresh
cheese indicated the obvious difference between the UF-
cheese and conventional cheese 27.7% and 11.2 %,
respectively. The higher NCN/TP ratio for UF-cheese was
attributed to the whey protein retained by the
ultrafiltration process which increases the proportion of
TAN in NCN from 3.4 % in conventional cheese to 49.8 % in
ultrafiltrate-derived cheese. These findings are consistent
with the work of Koning et al., ( 1981 ).

Free fatty acids are one of the major components which
contribute to cheese flavor. A typical reference
chromatogram of a mixture of fatty acids, representing the
fatty acid profile of milk fat, is shown in Figure 7A.
(Appendix 7). The means and standard deviations of free
fatty acids in fresh UF-cheese and conventional cheese are

presented in Table 20.

99

Table 19. Comparison of protein fractions (%N x 6.38)
between fresh Domiati cheese made by conventional and
ultrafiltrated methods

 

 

 

Protein UF-Cheese Conventional cheese
fractions
9/1009

Total Protein 14.78' 13.07b
Casein 10.69' 11.59b
Non-casein N 4.09' 1.47b
Non-protein N 1.50' 1.04b

Total albumin N 2.04' 0.05b
Soluble N 2.05' 1.42b

 

”HMeans within rows for each components with the same
superscripts are not significantly different (p < 0.05)

100

Table 20. Free fatty acids of fresh ultrafiltrate- and
conventional Domiati cheese

 

 

 

Free fatty Ultrafiltration Conventional

acid
mg/lOOg'
8:58:52 Meanisn

C4:0 2.110.29 3.2iO.66
C630 2.2iO.36 2.610.33
C8:O 2.010.21 2.4:0.10
ClO:0 3.4i0.85 1.910.73
C12:0 5.2t0.55 3.2iO.66
C14:0 12.3i1.1 10.ltl.3
C1630 31.0:1.56 25.111.41
C18:0 15.5tl.33 10.611.15
C18:1 ll.012.1 19.111.25
C18:2 4.0:0.8 2.7il.8
C18:3 2.010.94 1.310.80

W 90.5 82.2

 

'Values are the means and standard deviations of three
replications.

101

A pattern of eleven free fatty acids were identified in
fresh UF-cheese and conventional cheese. The total
concentration of the free fatty acids was 90.5 mg/100g and
82.2 mg/100g for UF-cheese and conventional cheese,
respectively. The higher content of free fatty acids in UF-
cheese was due to the higher concentration of the free fatty
acids in the Liquid pre-cheese as mentioned in part I.

The concentration of total volatile fatty acids (C:4 to C:8)
in conventional cheese ( 8.2 mg \100g ) was higher than in
UF-cheese ( 6.3 mg/lOOg ). 0n the other hand, the amount of
non-volatile fatty acids ( C:10 to C:18 ) was higher in UF-
cheese ( 84.2 mg/lOOg ) compared to conventional cheese (74
mg\100g). This decrease of volatile fatty acids in UF-
cheese may due to the low amount of these fatty acids in the
liquid pre-cheese used.

Free amino acids and very small peptides contribute in
part to the cheese flavor. The concentration of free amino
acids in the UF-cheese and conventional cheese are presented
in Table 21. Similar patterns for sixteen amino acids are
found in both cheeses. The data indicate that there is a
higher concentration of free amino acids in UF- cheese (262
mg/100g) than in conventional cheese (185 mg/lOOg).

Aspartic acid, lysine, glutamic acids, leucine and proline
account for 60.65 % of total free amino acids in UF-cheese,

whereas leucine, phenylalanine, lysine, aspartic and,

102

Table 21. Free amino acids and small peptides of fresh
Domiati cheese made by Diafiltration and conventional method

 

 

 

UF-cheese Conventional cheese
Free amino
acids
mg/100g*
Hflanfiifin Hfifinfiififi
Histidine 610.4 510.8
Threonine 911.3 811.0
Valine 1210.9 1111.0
Isoleucine 1811.8 1511.3
Leucine 2711.5 1911.1
Phenylalanine 2111.4 1811.2
Lysine 3311.9 1911.2
Cystine 210.8 211.5
Methionine 210.8 211.6
Aspartic acid 3412.9 1912.1
Glutamic acid 4012.7 2211.8
Sarina 1011.1 911.1
Glycine 911.0 710.9
Arginine 1011.5 810.9
Pro1ine 2512.5 1711.2
Tyrosine 410.8 410.7
IQ§§1_£‘AA 262 185

 

'Values are the means and standard deviation of three
replications.

103
glutamic acids account for 52 % of the total free amino
acids in conventional cheese. The higher concentration of
certain free amino acids in UF-cheese is related to the
higher concentration of free amino acids in the whey used
for making the cheese. This difference in the amino acid
profile could contribute to flavor characteristics of UF-

cheese and conventional cheeses.

WM]!

Densitometry was performed on the gels to quantitate
the relative changes in nitrogen fractions of conventional
and UF-cheeses. The densitometric pattern are presented in
Figure 16. Casein and whey proteins standards were run with
the cheese samples to allow the identification of the casein
components, a.-casein and fi-Casein, and the major whey
protein components, fi-Lactoglobulin and a-Lactalbumin.

These were identified by comparing of relative mobilities
and densitogram characteristics.

The electropherograms of conventional and UF-cheese
show the presence of whey protein. In UF-cheese, the a-
lactalbumin peak appears as a distinct zone ahead of the fi-
casein zone. The other whey protein zones ( fi-Lactoglobulin
A and B) overlap with the fi-casein zone. This

electrophoretic characteristic emphasized the results

104

 

 

 

 

 

 

 

 

1...}

Conventional Ultrafiltration

Figure 16. Discontinuous polyacrylamide gel electrophoresis
densitograms of conventional and ultrafiltrated fresh
Domiati cheese: A, B-casein: B. c.-casein; C, a-lactalbumin.

105
obtained by nitrogen fractionation ( Table 19 ) and is in
agreement with Koning et al.( 1981 ) and El-Shabrawy

( 1985 ).

greenglentis_n£222:ties

Sensory evaluation of fresh UF and conventional Domiati
cheese were judged for flavor, body, texture, and color by
judges familiar with Domiati cheese using cheese score card
with maximum scores given for the different attributes of
flavor, body/texture, and color. A copy of the score card
is provided in Figure 9A ( Appendix 9 ). Scores and
comparisons for the conventional and UF-cheese are presented
in Table 22. The evaluations indicate that UF-cheese was
liked better ( p< 0.05 ) when compared to the conventional
cheese. Ultrafiltrate-cheese was characterized by a creamy
color, a pronounced flavor and a consistently firm texture.
The higher concentration of the free fatty acids and free
amino acids in ultrafiltrated fresh cheese may explain the

higher sensory scores ( Tables 20 and 21 ).

£212:

Variables L, a and b were measured for color in
ultrafiltrate and conventional cheese and the data are

presented in Table 23. Variable (L), whiteness, was 93.3e

106

Table 22. Organoleptic properties of fresh Domiati cheese
using ultrafiltration and conventional methods

 

 

 

 

Cheeses Flavor Body Color Total
Texture Scores
Means1SD
Conventional 25.412.9 53.411.5 1010 88.80'
Ultrafiltration 27.711.4 57.511.8 910 97.15b

 

"Total scores that have different superscript differ
significantly at p< 0.05.
Body and Texture, 60 = Excellent.
Flavor, 30 - Excellent.
Color, 10 8 Excellent.

107

Table 23. Color ( L,a,b ) of fresh Domiati cheese made by
ultrafiltration and conventional methods

 

 

Cheeses L a b
Conventional 93.310.25 -3.310.l 10.010.15
Ultrafiltration 83.310.2 -3.810.2 12.610.2

 

Values are the means and standard deviation of duplicate
analyses of three replications.

LP indicates lightness: 100 =perfect white
as + indicates redness: - indicates greenness: 0 = gray

b= + indicates yellowness: - indicates blue: 0 = gray

108
for ultrafiltrate cheese compared to 83.3 for conventional
cheese. Instrumental value (L) and sensory scoring for color
show a high degree of correlation (0.98). Ultrafiltrate
cheese possessed a slightly creamer color than the
conventional cheese. These results agree with those of

Mahmmoud (1980). and El-Gendy et al.(1983 ).

W

A texture profile, indicating hardness, cohesiveness,
adhesiveness, gumminess and elasticity, is offered as a
means of helping the food researcher obtain descriptive
characteristics of a food ( Brandt et al.,1963 ). Typical
force-distance profiles obtained from the conventional and
ultrafiltrate fresh cheeses are illustrated in Figure 17.
Area and height of the diagram were measured and the data
related to mechanical properties are summarized in Table 24.
The data reveal that the texture characteristics of
ultrafiltrate Domiati cheese are significantly different at
p< 0.05 from the conventional Domiati cheese. UF-cheese was
firmer and more adhesive than conventional cheese. This
result was in agreement with Covacevich and Kosikowski
(1974) who stated that cream cheese produced by
ultrafiltration possessed more hardness, cohesiveness and
adhesiveness than conventional cream cheese. This
observation may be due to higher retention of calcium and

phosphorus associated with the casein micellar complex in

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

        

         

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
  

 

 

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109

110
liquid pre-cheese, which remained in the curd of the UF-
cheese, whereas in the conventional method, during
coagulation of the casein component, more micellar calcium
is solubilized and lost in the whey. Higher levels of
calcium affect the hardness of cheese ( Lawrence et al.,
1983 ). The rates of firming of curd formed from
ultrafiltrated milk increased in proportion to the extent of
concentration of the milk used for cheese manufacturing
(Reuter et al., 1981 and Green el al., 1981).

The data also, indicate that conventional cheese is
characterized by higher chewiness and gumminess than
observed in ultrafiltrated cheese. The two cheeses exhibit
no difference in texture related to cohesiveness and
elasticity. The mechanical measurement of texture was
confirmed by the sensory evaluation of the cheeses. And the
differences were related to the composition of the cheese as
well as the manufacturing process. Green et al. (1981)
suggested a possible role of fat in cheese firmness.

Reduced fat in the curd would result in a smaller fat-
protein interfacial area and an increased separation between
fat globules. The capacity of the fat and protein phases of
cheese to move in relation to each other would be reduced

and would consequently result in a firmer cheese.

111

Table 24. Texture profile analysis of fresh Domiati cheese
made by conventional and ultrafiltration methods

 

 

UF-cheese Conventional cheese
Hardness 9.00b 7.28'
Cohesiveness 0.31' 0.69'
Chewiness 1.36b 5.81'
Guminess 1 . 36" 2 . 91'
Elasticity 1.43' 2.25'
Adhesiveness 0.5 ND

 

'JMeans within rows for each components with the same
superscripts are not significantly different (p < 0.05)
ND- not detectable.

an: 111 .

um um none! vacuum “PM
0' name: curs: m: m
utmnmm nu

M95121:

Ripening of Domiati cheese is traditionally
accomplished by aging or pickling the cheese in salt brine.
Weight losses as high as 40 % of fresh curd weight have been
reported during pickling of Domiati cheese ( El-Shibiny et
al., 1973 ). When Domiati cheese is ripened in brine, the
retained whey protein dissolves to a great extent in the
brine. Possibly this loss could be avoided by ripening the
ultrafiltrate-cheese in vacuum pouch to maintain it's WPC.

The objective of this phase of the experiment was to
develop a vacuum packaging method for ripening Domiati
cheese and compare it to the conventional method of brine
ripening. Fresh Domiati cheese manufactured from
ultrafiltered / diafiltered milk by the MMV method, was
vacuum packed in polyethylene-lined aluminum pouches and
ripened for two months. The experimental cheese was

compared to a control cheese packed in brine.

MW:

To examine the difference between the two methods of
ripening and the changes occurring during storage, two
analytical designs were followed. First, total solids, fat,

protein, ash, lactose, free fatty acids and texture profile

113

114
analysis of cheese were analyzed by a one-way analysis of
variance. If the F-test proved significant, the Dunnett's
procedure was applied to determine the significant
difference at p< 0.05 and < 0.01 between fresh cheese and 2,
4, 6 and 8 weeks ripened cheese within the same method of
ripening. Second, to compare the two methods of ripening at
the same time, e.g., 2, 4, 6 and 8 weeks, a split-plot
repeated measurement was followed and a T-test was used to
differentiate the means at p< 0.05 significance (Gill,

1978 ).

Ens-1231.22322115123
Whole milk was ultrafiltered / diafiltrated and the

final retentate was freeze dried to total solids of 98.99 %
and kept in dark brown jars until used for the manufacture
of cheese. Retentates were\reconstituted in warm water
(40°C) to a composition close to fresh retentates ( Table 25
). The composition of Domiati cheese made from
reconstituted freeze dried retentate (RFDR) is presented in
Table 26. These data reveal that fresh cheese made from
RFDR exhibited a higher moisture content than fresh cheese
produced by conventional methods as cited previously in Part
II in this thesis.

The nutritional value of fresh Domiati cheese could be
assessed from the amino acid profile of cheese, presented in

Table 27. The data reveal that the total essential and

115

Table 25. The composition of ultrafiltrated freeze-dried
whole milk

 

 

Moisture Fat Protein Ash Lactose
% % % % %
Eganfiifin
70.210.9 14.0tO.61 12.05i0.8 2.18:0.21 l.9510.35

 

Values are duplicate analyses of three replications.

Table 26. The composition of fresh Domiati cheese made from
Ultrafiltrated whole milk

 

 

Moisture Fat Protein Ash Lactose
% % t % %
usinfiififl
65.07iO.7 14.510.6 12.5510.45 6.01:0.45 1.54:0.16

 

Values are duplicate analyses of three replications.

116

Table 27. Total and free amino acid content of fresh
Domiati cheese made from ultrafiltrated whole milk

 

 

 

 

Total Free

Amino Acids mm mm
Means1SD Means1SD
mg/lOOg'
W
Histidine 330119 511.00
Threonine 510121 811.15
Valine 830117 1011.58
Isoleucine 1080136 1111.20
Leucine 710126 1411.95
Phenylalanine 590118 510.95
Lysine 1020135 2412.33
Cystine 3018 ND
Hethionine 170110 ND
.
Aspartic acid 980115 2511.73
Glutamic acid 2490156 3512.65
Serine 610118 911.39
Glycine 240128 711.00
Arginine 510119 811.00
Alanine 410121 811.20
Proline 991165 1711.22
Tyrosine 640118 110.40
IQ§§1_A1A 12.141 187

 

'Values represent the means and standard deviation of three

determination.
ND- not detectable.

117
nonessential amino acids accounts for 5.27 and 6.87 g/100g
cheese, respectively. Essential amino acids account for 43
% of the total amino acids in fresh cheese with higher
values of isoleucine, lysine followed by valine,
phenylalanine and thyronine. The low values for sulfur amino
acids, cysteine and methionine, may due to destruction
during the analysis as mentioned before.

Domiati cheese can be consumed fresh as well as a
ripened cheese, so the characteristics of fresh cheese with
respect to free amino acids, free fatty acids, protein
fraction, color and texture will be monitored through out
the ripening study.

The effect of the ripening period on cheese composition
and characteristics was studied. Compositional changes
after 2, 4, 6 and 8 weeks of ripening in vacuum pouches
are recorded in Table 28. These data demonstrated a
statistical difference (at p< 0.05 and 0.01 ) between fresh
cheese and the cheese ripened for 2, 4, 6 and 8 weeks. The
means of total solids, fat, protein and ash increased from
34.93, 14.5, 12.55, and 6.01 % to 39, 17.23, 13.5 and 6.66
after 1 month and to 42.15, 18.3, 15.3 and 6.96 % after 2
months, respectively. The chemical composition of brine-
ripened cheese after 8 weeks are presented in Table 29.
Increases in total solids, fat, ash and protein show
significant difference (at p< 0.01) after 4 and 8 weeks
compared to fresh cheese. The increase in protein content

was not significant (at p< 0.05) prior to the sixth week,

118

Table 28. Chemical changes of Domiati cheese made from
reconstituted, diafiltrated whole milk and ripened in
pouches for 8 weeks

 

Composition (%)

 

 

Ripening

time

(Weeks) Total solids Fat Protein Ash
0 34.93 14.50 12.55 6.01
2 37.64“ 16.63" 13.38 6.20
4 39.00” 17.23” 13.50 6.55'
6 40. 07” 17 . 55” 14 . 60” 6. 77*
8 42.15” ' 13.30“ 15.30” 6.96’

 

* p < 0.05 and ** p < 0.01 ) for differences among values of
each column compare to zero time.

Standard errors for T8, Fat, protein and Ash are 0.3, 0.28,
0.40, 0.17, respectively.

119

Table 29. Chemical changes of Domiati cheese made from
reconstituted, diafiltrated whole milk and ripened in 8%
brine solution for 8 weeks

 

 

 

Ripening Composition (%)

time

(weeks)

Total solids Fat Protein Ash

0 34.93 14.50 12.55 6.01
2 35.11 15.03“ 12.30 6.61“
4 36.00” 15.40” 12.50 7.17"
6 36. 95" 15. 87” 12 . 79" 7 . 56”
a 37.90" 16.20” 13.00‘ 7.90”

 

* p < 0.05 and ** p < 0.01 ) for differences among values of
each column compare to zero time.

Standard errors for Ts, Fat, Protein and Ash are 0.3, 0.27,
0.29, 0.19, respectively.

120

 

 

 

     

 

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AXV «cameo: £381

Ripening Time ( Weeks )

Composition of protein fractions of Domiati cheese

Figure 18.
made from or whole milk and ripened in pouches or in 8% brine.

TP= total protein, NCN: non-casein nitrogen,

NPN: non-protein nitrogen.

121
while increased significantly after 6 and 8 weeks.
Statistical comparisons of cheese ripened in pouches and in
brine after 2, 4, 6 and 8 weeks are presented in Table 10A,
Appendix 10. The result indicated that cheese ripened in
pouches had higher total solids, fat and protein at any time
observed than cheeses ripened in brine solution. The
observed increases in values reached maximum after 2 months
of ripening. These results are in agreement with those
obtained by Mahmmoud and Kosikowski (1979) and El-Gendy et
al. (1982).

Cheese ripening is a dynamic process during which the
proteins undergo considerable decomposition. Schormuller
(1968) stated that a complex mixture of decomposition
products including proteose, peptones, peptides, amino
acids, amines and ammonia is formed during cheese ripening.
And the changes in cheese proteins were dependent on the
variety and stage of maturity of the cheese. In this study
the protein fractions were studied for the two methods of
ripening and the mean values plotted in Figure 18. Changes
in the protein fractions of pouched cheese were more
pronounced than brine-treated cheese at any time of
ripening. Total protein (TP), non-casein nitrogen (NCN)
and non-protein nitrogen (NPN) were 12.55%, 2.31% and 1.02
%, respectively, for fresh and increased significantly (p<
0.01) to 15.30%, 3.37% and 2.2%, respectively, for pouched-
ripened cheese and to 13%, 2.22% and 1.48%, respectively,

for brine ripened cheese (Table 10 B, Appendix 10). The

122

Table 30. Ripening index' of Domiati cheese ripened in
pouches and in 8% brine solution for 8 weeks

 

 

 

 

Pouch 8% brine
Ripening
(weeks) Ripening index
NCN/TN NPN/TN NCN/TN NPN/TN
0 18.40 8.12 18.40 8.12
2 19.86 11.33 15.40 9.42
4 20.74 12.74 15.60 10.14
6 21.18 13.01 16.42 10.95
8 22.02 14.37 17.07 11.45

 

Values represent the means of three replications.
Ripening indices are: Non casein nitrogen/Total nitrogen
and Non protein nitrogen/Total nitrogen.

123
ratio of NCN/TN has been used to monitor the aging of cheese
(Noomen, 1977; El-Salam et.a1., 1981; and El-Shabrawy,
1985). The nitrogen-distribution data revealed, as shown in
Table 30, that the NCN/TP ratio increased to 22.02 after 2
months in pouches compared to 17.07 for brine-ripened
cheese. This difference indicates a higher proteolytic
activity in the pouch. The NPN/TP ratio was 8.12 for fresh
cheese and increased to 12.74 and 14.37 for pouch comparing
to 10.14 and 11.45 for brine after 1 and 2 months,
respectively. The ripening index was lower in brine cheese
because of increased exudation of cheese serum carrying more
soluble N from the cheese ( Abd El-Salam and El Shibiny,
1982 ). Salt content, or salt-in-moisture (SM) of the
cheese, could influence hydrolysis of protein during

ripening (Lawrence and Gilles 1982: Thomas and Pearce 1981).

111114914:
The pattern of the free fatty acid composition in fresh

Domiati cheese and the changes occurring during the two
methods of ripening are presented in Tables 31 and 32.
Eleven free fatty acids were identified in fresh cheeses,
totaling to 74.9 mg/lOOg. The liberation of free fatty
acids in cheese ripened in a pouch ( Table 31 ) showed
highly significant increases in total FFA with values of
130.4, 173.6 and 226.7 mg/lOOg after 2, 4 and 8 weeks,
respectively. This increase of the FFA due to some

lipolysis occurs during the ripening. Cheese ripened in

124

Table 31. Quantitative changes of free fatty acids in
Domiati cheese made from ultra/diafiltrated whole milk
ripened in pouches for 8 weeks

 

 

 

 

Free fatty Ripening Time (Weeks)
acids
0 2 4 8
Standard
errors
mg/100g'
04:0 1.47 2.07 2.99” 4.85" 0.11
C6:0 2.87 3.22 10.12” 12.65” 0.16
08:0 1.75 4.92” 13.34” 18.40" 0.10
c10:0 2.76 3.36 3.47 7.77” 0.11
012:0 1.65 1.80 1.92 2.96" 0.07
014:0 11.50 17.36” 17.87” 20.70“ 0.12
016:0 29.90 35.65" 38.87“ 47.60“ 0.08
018:0 11.73 12.42 21.62” 27.69” 0.12
018:1 5.24 32.15" 41.86” 74.75" 0.17
C18:2 2.64 11.27" 12.24” 17.96“ 0.14
018:3 0.62 3.79” 7.15" 7.36“ 0.14
Total 74.3 130.36 173.6 226.68

 

Means within a row are significantly different at *, p <
0.05; **, 0.01 from fresh ( 0 time ).

Values are the means and standard errors of three
replications.

125

Table 32. Quantitative changes of free fatty acids in
Domiati cheese made from ultra/diafiltrated whole milk
ripened in 8% brine for 8 weeks

 

 

 

 

Free fatty Ripening time ( Weeks )
acids
0 2 4 8 Standard
errors
mg/lOOg

04:0 1.47 1.72 2.28 2.76’ 0.14
06:0 2.87 2.99 8.74" 10.05” 0.13
08:0 1.75 1.89 3.15“ 5.29“" 0.11
010:0 2.76 2.99 3.11 4.14‘ 0.11
012:0 3.79 3.59 5.66" 6.83” 0.12
014:0 11. 50 11.96 19.44” 24 . 61“ 0. 16
016:0 29.90 34.66" 40.62“ 43.95” 0.19
018:0 11.73 14.26” 18.17” 20.15“ 0.11
018:1 5.24 30.13” 38.18“ 40.94” 0.14
018:2 2.62 7.15” 7.89” 23.76" 0.16
C18:3 0.62 2.30"" 2.99” 5.64" 0.10
193;; 74.3 122.8 150.21 188.1

 

Sample with the same raw are significantly differ from fresh
at * p< 0.05: ** 0.01 .

Value are the means and standard errors of three
replications.

126
brine showed increases in free fatty acids to 122.8, 150.2
and 188.1 mg/100g, respectively, for similar times of
ripening ( Table 31 ). The percent of volatile fatty acids
( C4-C10 ), which contribute to cheese flavor, was higher
(20 % of total) in pouch ripened cheese than in brine-
ripened cheese (11.8% of total) after 2 months of ripening.
This result is in agreement with the data obtained by
Buruiana and El-Senaity ( 1986 ) in their study on white
soft cheese. Rabie et al.( 1984 ) stated that ripening of
Domiati cheese made from dried milk took place at a
relatively slow rate compared with cheese made from fresh
milk. Generally, long chain free fatty acids were more
prevalent than the short chain species in UF-cheese,
probably as a result of ultrafiltration process. Analysis
of variance for the two methods of ripening showed that
pouch-ripening favored the formation of total free fatty
acids, especially after two months. This result was
confirmed by the flavor evaluation score ( Table 34 ) and is
in agreement with Morris (1970), who found that good flavor,
color and uniform composition can be obtained in cheese made

from pasteurized cow milk and ripened in pouches.

mm;

The quantity of free amino acids accumulated during the
ripening period was the direct result of liberation of amino
acids from casein and a transformation of amino acids

already liberated into further decomposition products.

127

The changes in amino acid composition during ripening
of Domiati cheese in pouches and brine are presented in
Table 33. The concentration of free amino acids increased
from 187 mg/lOOg in fresh cheese to 397 and 791 mg/100g in
brine-ripened and pouch-ripened cheese respectively, after 2
months. These results illustrate the greater breakdown of
proteins in pouch-ripened cheese. The low-concentration of
free amino acid in brine cheese may be attributed in part to
the loss of free amino acids in the brine. This result
agrees with El-Sadek and Abd El-Motteleb ( 1958 ) who
ascribed the lower concentration of free amino acids in more
ripened Domiati cheese to the brine solution. Also, free
glutamic acids, proline, lysine and leucine, which are
mainly responsible for the formation of cheese flavor, were
found in greater concentration in pouched cheese compared to
brine-ripened cheese. The concentration of glutamic acid,
leucine, aspartic acid and lysine represent about half of
the total free amino acids present in Domiati cheese ( Table
33 ). This observation is in agreement with that reported
by Buruiana and Frag ( 1983 ) and Omer et a1. ( 1987 ) in
their study on white soft cheese.

These results indicate that as total free amino acids
increase, the flavor of the cheese increase and that a sharp
increase in amino acid concentration coincide with optimum
flavor and body. The variation in the rate of production

of certain amino acids after ripening reaches a certain

128

Table 33. Free amino acid contents of ripened Domiati
cheese made from ultra/diafiltrated whole milk and ripened
in pouches and brine solution after 8 weeks

 

 

 

Fresh Pouch Brine

Free Amino
Acids mg/100g

usinfiififl MQQDEIED Mfiénfiififl
Histidine 511.00 2111.9 1112.0
Threonine 811.15 3212.7 1812.2
Valine 1011.58 5912.6 2411.9
Isoleucine 1111.20 4113.6 2211.9
Leucine 1411.95 7512.6 3112.3
Phenylalanine 510.95 3311.8 1911.2
Lysine 2412.33 9913.5 4412.3
Aspartic acid 2511.73 4512.2 3612.1
Glutamic acid 3512.65 17514.1 8613.2
Serine 911.39 4811.3 2312.1
Glycine' 711.00 1511.3 9010.6
Arginine 811.00 2411.9 1511.1
Alanine 811.20 2612.1 1311.2
Proline 1711.22 8913.5 4213.3
Tyrosine 110.40 110.2 210.2
Cystine ND 310.5 11.05
Methionine ND 210.3 ND
Ammonia ND 510.8 1111.9
W 137 793 397

 

‘Values are the results of three determinations.
ND - not detectable.

129
point makes it difficult to evaluate the role of free amino

acids in the development of typical Domiati cheese flavor.

WW
Using the cheese Score card as a guide ( Figure 9A,

Appendix 9), fresh and ripened cheese were evaluated for
flavor, body /texture and color by experienced judges who
were familiar with Domiati cheese; the scores are presented
in Table 34. Fresh cheese was scored 80.5. Pouch-ripened
cheese was scored 88 and 94 after 4 and 8 weeks,
respectively. Cheese ripened in brine for similar periods
scored 83.5 and 85.0, respectively.

Vacuum treatment compacts the cheese, produce a close
texture and smooth surface, which also aids in preventing

mold growth and spoilage ( Morr and Richter, 1988).

9212:

Color evaluation for fresh and ripened cheeses are
presented in Table 35. The changes in color, variable L, a
and b, reflected differences in the method of ripening.
Variable L (whiteness) was 82.6 in fresh cheese and changed
to 79 for pouch compared to 89.3 for brine-ripened cheese
after 8 weeks of ripening. Variable b (yellowness) was 11.2
for fresh and changed to 18.74 for pouch compared to 9.5 for
brine cheese after 8 weeks of ripening. This result
indicates less whiteness and more yellowness in pouch-

ripened cheese than brine-ripened cheese. The sensory

130

Table 34. Organoleptic properties of fresh Domiati cheese
made from ultra/diafiltrated whole milk and ripened in
pouches and 8% brine solution for 8 weeks

 

 

 

 

 

 

Ripening Flavor Body/Texture Color Total
(Time) .
Fresh 2411.5 4712 9.510.3 80.5
EQBQD
4 Weeks 2911 5011.5 9.010.7 88.0
8 Weeks 3010 5612.2 8.011.0 94.0
man:
4 Weeks 2511.3 4911.9 9.510.5 83.5
8 Weeks 2612.0 4912.5 10.010.0 85.0

 

Values are the mean and standard deviation of duplicate
analyses of three replications.

Flavor 30 = Excellent.

Color 10 - Excellent.

Body and Texture 60 - Excellent.

Table 35.

131

Color profile of Domiati cheese made from
reconstituted freeze dried ultrafiltrated whole milk and
ripened in pouches and 8% brine solution for 8 weeks

 

 

 

 

 

 

Ripening L a b

time

Fresh 82.65:0.35 -5.65¢0.15 11.2010.21
2911911

4 Weeks 80.33i0.33 -3.90¢0.10 14.60i0.08

8 Weeks 79.00i0.30 -2.3330.14 18.74:0.30
11.512111:

4 Weeks 83.5010.50 -4.90¢0.10 10.20i0.45

8 Weeks 89.30i0.40 -1.44i0.04 9.50:0.27

 

Values are the means and standard deviations of duplicate

analyses of three replications.

L = indicates 1ightness( 100 =perfect white)
a - + indicate redness; - indicate greenness; 0 = gray
b s + indicate yellowness; - indicate blue; 0 a gray

132
evaluation confirmed the result which represented brine-
ripening cheese as being whiter than pouch-ripened cheese.
Pouched cheese ripened in the absence of salted whey was
attractive with a uniform, creamy color. Similar observation
were made by Morris ( 1970 ), El-Gindy et al.( 1983 ) and

Mahmmoud ( 1980 ).

W

The structure and arrangement of the protein (mainly
casein) molecules are largely responsible for the textural
characteristic of cheese. Also, fat and moisture affect the
rheological quality and acceptability of the finished cheese
( Fukushima et al., 1965 ). The mechanical measurements of
hardness, cohesiveness, chewiness, gumminess and elasticity
for fresh Domiati cheese and cheeses ripened in pouches or
in brine are presented in Figures 19 to 23.

Values for hardness, chewiness and gumminess increased
significantly ( at p< 0.05 and p< 0.01 ) from 3.85, 5.09 and
2.21 for fresh cheese, respectively, to 9.85, 12.39 and 6.21
for pouch cheese ripened for 2 months ( Table 10C, Appendix
10 ). Compared to brine ripened cheese, the mean values of
hardness and chewiness increased significantly from 3.85 and
5.09, respectively, to 5.63 and 6.04 after 2 months ( Table
10D, Appendix 10 ). For both ripening methods, cohesiveness
and elasticity did not show any significant difference (P<

0.05, 0.01) at any time of ripening.

133

 

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UF whole milk and ripened in pouches 0nd in 8% brine. NaNewtons.

134

 

 

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Ripening Time (Weeks )

Figure 20. Gumminess changes on Domiati cheese made from

UF whole milk and ripened in pouches 0nd in 8% brine. N-Newtons.

135

 

 

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Ripening Time ( Weeks )

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UF whole milk and ripened in pouch and in 8% brine. N-Newtons.

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UF whole milk and ripened in pouches and in 8% brine.

 

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137

 

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Ripening Time (Weeks )
Figure 23. Elasticity changes an Domiati cheese made from
UF whole milk and ripened in pouches and in 8% brine.

138

Chemical and physical changes in cheese during ripening
cause the body of freshly made cheese to lose its curdy
texture and become soft. This phenomenon is related
principally to the breakdown of protein to smaller peptides
and the gradual accumulation of amino acids ( Ernstrom and
Wong, 1974). Lawrence et al.( 1983 ) stated that moisture,
pH and casein proteolysis could affect the texture of
cheese. To compare the effect of the two methods of
ripening on the rheological properties on Domiati cheese,
one-way analysis was used and the data are presented in
Table 36. At any time of ripening, hardness is
significantly higher for pouch-ripened cheese, indicating
more firmness. Chewiness and gumminess showed a significant
difference after 1 and 2 months with higher values for
pouch-ripened cheese. Elasticity and cohesiveness were not
significantly different at any stage of the ripening
periods.

W

During the ripening process, the serum exuded from
pouch-packed cheese and into the brine solution of brine-
ripened cheese were analyzed at 2, 4, 6 and 8 weeks. Fat
and protein values of pouch-serum and the brine solution are
presented in Table 37. The amount of fat and protein
released from pouches cheese were 0.25 % and 3.70 %,
respectively, after 2 weeks and increased to 0.39 and 4.19

%, respectively, after 8 weeks. 0n the other hand, the

139

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140
amount of fat and protein in the brine solution was 0.13 and
0.52 %, respectively, after 2 weeks and increased to 0.23
and 1.16 %, respectively, after 8 weeks. The observed
increase in fat and protein in the serum and brine did not
change significantly during ripening ( Table 10E ) Appendix
10. Comparison of the above components in the serum and
brine obtained from both cheeses during ripening show that
there was a significant difference at p< 0.05 at any time of
ripening ( Table 37 ). Because the amount of exuded serum
from pouch cheese was very small compared to the volume of
the brine solution, the actual loss of the fat and protein
in the whey of both cheeses was calculated in relation to
the volume produced throughout the ripening process. The
data in Table 10F, Appendix 10, indicate that the loss of
components was higher in the brine solution than in the
pouch-serum. These results are in agreement with those
stated by Mahmmoud and Kosikowski ( 1980 ).

Domiati cheese produced from ultrafiltrated whole milk
and ripened in a pouch-pack represents a suitable means of
packaging eight ounce ( 225 gm ) portions immediately
following manufacture. This allows the presentation of
Domiati cheese in a convenient, self-service pack and
retailed in a form which overcomes the disadvantage of bulk-
dispensing in brine and maintains the cheese " in the
natural state " until the package is opened for consumption.
Good flavor, texture and color and uniform composition can

be attained with ripening the cheese in a pouch.

141

Table 37. Fat and protein content of serum and brine
obtained from Domiati cheese made from ultrafiltrated whole
milk ripened in pouches and 8 % brine solution for 8 weeks

 

 

 

 

Ripening Fat (%) Protein (%)

time

( week )

Pouch Brine Pouch Brine

2 0.25‘ 0.13' 3.70' 0.52”
4 0.36' 0.15b 3.99' 0.79b
6 0.33' 0.18b 4.00' 0.88b
8 0.39' 0.23” 4.19' 1.16”

 

'”Means within rows for each components with the
same superscripts are not significantly different
(p< 0.05) at the same ripening time.

PART IV

COKPARISON BETWEEN CONVENTIONAL AND
WIWRD DONIATI CHEESE
DURING RIPENING IN POUCHES

Egyptian white, Domiati cheese is marketed mostly as
pickled, ripened cheese. The objective of this experiment
was to determine the feasibility of using a new ripening
method (vacuum pouch) and its effect on the quality of
ultrafiltrate-derived and conventional cheese made from

concentrated liquid pre-cheese and whole milk, respectively.

W329

Domiati cheese was manufactured by two methods: namely,
by the MMV method from liquid pre-cheese, and by the
conventional methods. After ripening for three months at 7-
10°C under vacuum in polyethylene-lined aluminum pouches,
compositional changes were studied. These data are
presented in Figure 24 and 25 and demonstrate that both
conventional and ultrafiltrate-derived cheese ( UF-cheese )
follow similar changes in composition during the ripening
process. Total solids, protein and fat of ultrafiltrate-
derived cheese significantly increased from 36.9 %, 14.78 %
and 15.75 %, respectively, to 38.9 %, 15.46 % and 18.0 %
after 1 month and 42.4 %, 17.68 % and 18.69 % after 3
months, respectively ( Figure 24 ). Conventional cheese
increased from 38.1, 13.07 and 18.0 % for total solids,

protein and fat, respectively, for fresh cheese to 39.1,

143

144

 

-Ash
m Salt

- Total solids
Protein

m Fat

.0
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Composition changes of Domiati cheese made by

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A x v coEmanoO

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R
the ultrafiltration method and ripened for three months in

Figure 24.
pouches.

145

-Ash
m Salt

- Total solids
Protein

m Fat

 

                
       

   

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A x v coEmanoo

Composition changes of Domiati cheese made by

the conventional method and ripened for three months in

Figure 25.
pouches.

146
13.45 % and 19.4 % after one month ripening and to 40.93 %,
14.36 and 21.5 % after 3 months ripening, Figure 25.
Compositional changes between the conventional and UF-cheese
after one and three months of ripening in vacuum packs are
presented in Table 38. The data reveal that, after one
month of ripening ,there was no significant difference in
total solids between conventional and ultrafiltrate-derived
cheese ( p< 0.01 ), whereas there were significant
differences for protein, fat, ash and salt, with higher
values for the UF-cheese. After three months of ripening,
UF—cheese was significantly higher in protein and fat than
conventional cheese. No difference was noted in total
solids, ash and salt between the ultrafiltrate and
conventional pouch-ripened cheese. During a similar
ripening period, salt and ash decreased significantly in
both cheeses. However, the decrease in salt concentration
was not significant in UF-cheese compared to conventional
cheese.

The effect of ripening time on conventional and UF-
cheese was calculated, indicating that the percentage
increases in total solids, protein and fat in 3 months old
UF-cheese were 14.9, 20.8 and 18.7 %, respectively, compared
to the fresh cheese. Similarly, increases of 7.4, 9.8 and
19.4 % for TS, protein and fat, respectively, were recorded
for conventional cheese after 3 months. Also, ash and salt
decreased by 11.4 and 16.3 %, respectively, in UF-cheese and

7.8 and 21.4 % in conventional cheese after the same period

147

Table 38. Chemical changes of ultrafiltrate-derived and

conventional Domiati cheese ripened for 1 and 3 months in

 

 

 

 

 

pouches
Ripening Period
Composition 1 Month 3 Months
UF Conventional UF Conventional

Total solids 38.90' 39.10‘ 42.40' 40.93'
Protein 15 . 46' 13 . 45b 17 . 86' 14 . 36"

Fat 18 . 00' 19 . 40b 18 . 69‘| 21 . 50'3

Ash 4.60' 4.32” 4.32' 4.20'
Salt 2.52' 2.20" 2.40‘ 2.20“

 

Means within a row for the

(p< 0.01).

same period of time having
different superscripts are significantly different at

148
of ripening. Changes in the nitrogen distribution in
Domiati cheeses made by conventional and UF methods and
ripened in pouches under vacuum were assessed ( Table 39 ).
Three ripening indices were derived from the nitrogen
fractions of cheese and were used to follow the ripening
process. Apparent ripening extension Index (ARE) represents
the ratio of non- casein nitrogen (NCN) to total nitrogen
(TN), accounting for total proteolytic activity. Actual
ripening extension (RE) represents the ratio of soluble
nitrogen (SN) to (TN), which corrects for the effects of
initial (TAN) level in UF-cheese. Ripening depth index (RD)
represent the ratio of NPN to TN which accounts for the
amino-peptidase activity of starter bacteria in the cheese
( Wolfschoom, 1983 ). The changes noted in ARE, RE and RD
values in conventional and UF-cheese after a ripening period
of three months at 7-10 °C are recorded in Figure 26. The
ARE index increased to 43.7 % for UF-cheese compared to 22.7
% for conventional cheese indicating more proteolytic
activity in the UP cheese. The RE index was 29.1 % for UF-
cheese and 18.6 % for conventional cheese. The data in
Table 11A, Appendix 11, indicate that Uf-cheese was higher
in ripening index than conventional cheese during the same.

period of time.

W

The extent of flavor developed during cheese ripening

was assessed by measuring the concentration of free fatty

149

Table 39. Changes in protein fractions (%Nx6.38) during
ripening of conventional and UF- Domiati cheeses in pouches

 

Ripening Period

 

 

 

Protein
fractions 1 Month 3 Months

UF Conventional UF Conventional
Total protein 15.46“ 13.45b 17.86' 14.36b
Non-casein N 5.40' 1.89b 7.80' 3.26b
Casein N 10.06' 11.55b 10.06' 11.09b
Non-protein N 2.40' 1.31b 3.10' 1.83b
Total albumin N 2.60' 0.58b 2.60' 0.58b
Soluble N 2.80‘ 1.49b 5.20' 2.68b

 

'WMeans within the same row that has different superscript
are significantly different at (p< 0.01).

 

150

 

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x000. 050031

Ripening Time ( Months )

conventional and or methods and ripened for three months in

Figure 26. Ripening index of Domiati cheese made by
pouches. ARE: apparent ripening extention, RE: actual

ripening extention, RD: ripening depth index.

 

Table 40.

151

cheese for three months in pouches

Free fatty acids of fresh and ripened UF Domiati

 

Ripening time

 

 

 

Free

fatty Fresh 1 Month 3 Months

acids

mg / 100 g
Meanifin Meanifin Meanifin

C4:0 2.110.19 4.510.26 10.110.84
C6:0 2.210.66 2.310.71 10.310.73
C8:0 2.010.21 2.810.33 9.010.71
C10:0 3.410.85 6.910.79 23.910.83
C12:0 5.210.43 10.310.85 24.910.90
Cl4:0 12.311.10 25.011.30 57.111.45
C16:0 31.011.36 58.011.76 104.011.86
Cl8:0 15.511.33 37.011.29 70.411.73
C18:1 11.012.10 37.812.30 95.012.15
C18:2 4.012.00 15.012.40 40.012.70
C18:3 2.010.94 5.210.76 8.010.90

Ig§g1_£‘za 90.7 204.8 452.7

 

Values are the means and standard deviations of three

replications.

Table 41.

152

Free fatty acids of fresh and ripened

conventional Domiati cheese for three months in pouches

 

Ripening Period

 

 

 

Free

fatty Fresh 1 Month 3 Months

acids

mg/100 g
Heanifin Meanifin Meanifin

C4:0 3.210.26 5.710.45 12.010.83
C6:0 2.610.13 4.310.36 11.510.56
C8:0 2.410.08 3.810.23 10.510.78
C10:0 1.910.23 5.010.46 19.610.83
C12:0 3.210.46 8.910.58 14.311.30
C14:0 10.111.30 19.811.56 40.611.77
C16:0 25.111.21 54.711.15 98.711.45
C18:0 10.611.15 21.911.21 55.411.96
C18:1 19.111.05 27.811.22 55.611.55
C18:2 2.711.80 13.911.79 30.811.37
C18:3 1.310.83 3.610.93 7.011.39
195a1_E&£‘A 82.2 169.4 356.0

 

Values are the means and standard deviations of three
replications.

 

153
monitored during the ripening of conventional and
ultrafiltrated cheese is presented in Tables 40 and 41. UF-
cheese which was ripened for three months possessed higher
concentration of liberated fatty acids (452.7 mg\100g
cheese) than conventional cheese (356 mg\100g cheese) after
3 months of ripening. The percentage increase in free fatty
acids for the UFscheese was 400 % compared to the fresh
cheese. Free fatty acids of conventional cheese increased
by 333 % compared to its fresh counterpart. These results
are in agreement with those reported by Omar (1987).
Conventional cheese possessed a more pronounced flavor than
UF-cheese, probably as a result of the higher concentration

of short chain fatty acids.

W

The extent of proteolysis during cheese ripening was
ascertained by measuring the concentration of free amino
acids released. The concentration of amino acids liberated
from both UF-derived and conventional cheeses were
substantially increased as a result of ripening. A summary
of free amino acids released from the conventional and UF-
cheese after three months of ripening is presented in Table
42. Both UF-cheese and conventional cheese were
substantially higher in total free amino acids than their
fresh counterpart. After three months of ripening, the

increase in amino acids liberated from UF-cheese were more

154

Table 42. Free amino acids of Domiati cheese made by
ultrafiltration and conventional methods and ripened for
three months in pouches

 

 

 

ultrafiltration Conventional
Free amino
acids
mg/100g Cheese
Emu
Histidine 3510.6 1510.8
Threonine 5010.8 1711.0
Valine 6911.0 3410.9
Isoleucine 6611.1 2211.2
Leucine 9012.0 4010.7
Phenylalanine 6310.9 2811.1
Lysine 11511.5 6912.0
Methionine 910.95 711.3
Cystine 1012.00 711.9
We
Aspartic acid 10411.0 3510.79
Glutamic acid 23012.3 6510.59
Serine 5010.8 1211.3
Glycine 2910.71 1211.0
Arginine 4410.90 1510.49
Praline 10611.2 2511.6
Tyrosine 4210.79 1210.99
19:31_E151A 1112 415

 

Values are the means and standard deviation of three
replications.

 

155

acids. The percentages of free amino acids observed in UF-
chesse was more than double that observed in conventional
cheese. In UF-cheese, lysine, aspartic acid, glutamic acids
and proline accounted for 50 % of the total free amino
acids, increasing the most after 3 months of ripening. As
compared to conventional cheese, valine,leucine, lysine,
aspartic and glutamic acids accounted for 58 % of the total.

The remaining residues increased slightly throughout
the ripening period. The relative proportions of individual
free amino acids remained essentially constant throughout
the ripening period for both cheeses as was reported by
Jarret et al.( 1982 ).

The general increase in free amino acids during
ripening can be explained on the basis of the higher
proteolytic action of microbial enzymes which produce a

range of peptidases ( MOu et al., 1975 ).

W

The proteolytic activity in ripened Domiati cheese was
examined using discontinuous polyacrylamide gel
electrophoresis ( PAGE ). The densitograms of the main
nitrogen fractions of fresh conventional and UF-derived
cheeses and those pouch-ripened for three months at 7-10%:
are illustrated in Figure 27. Ripened cheese showed
different electrophoretic patterns. UF-cheese demonstrated
that extensive protein degradation occurred, particularly in

the afl-casein zone with many minor bands which migrated

 

Conventional
it

13
A
Fresh Ripened
£3
1% B ’ ’Y
i
£‘ Ultrafiltration
it
13
Fresh
Ripened
O
C
‘J—v—vJ "1'

Figure 27. Discontinuous polyacrylamide gel electrophoresis
densitograms of fresh and ripened (3 months) conventional
and ultrafiltrated Domiati cheese; A. B-cesein: B, a.-

casein; C, a-lnctslbumin.

 

 

 

 

156

157
rapidly. The cleavage of afl-casein mostly due to rennet
activity (Olson 1982). Beta-casein was more resistant to
degradation which is in agreement with results from other
studies ( Green et al., 1981; Koning et al., 1981; and El-
Shabrawy, 1985). The proteolytic breakdown of fi-casein are
strongly retarded by the presence of salt ( Fox and Walley

1971).

90:11:.023111!

Cheese is ripened by the action of the rennet and
microorganisms during the cheese making and cheese ripening.
Degradation of casein during ripening affects the texture,
flavor and taste of cheese. Harper ( 1959 ) reported the
relationship between the physicochemical changes and taste
of cheese during ripening.

The color and textural qualities of conventional and
UF-Domiati cheese during ripening for three months at 7-10W:
were studied. A typical texture profile analysis of
conventional and ripened UF Domiati cheese, obtained by the
Instron Universal Machine, is presented in Figure 28. In
cheese ripening, primary and secondary activities result in
the accumulation of lactic acid, free fatty acids and free
amino acids. The mechanical measurements of hardness,
cohesiveness and gumminess are presented in Figure 29. As
the data reveal, both UF and conventional cheeses show the
same trend of greater hardness, cohesiveness and gumminess

after one month, then decrease after three months of

 

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Figure 29. Hardness, cohesiveness and chewiness of Domiati
cheese made by conventional and ultrafiltrated methods and
ripened tor 3 months in pouches. N: Newtons. A, and 32
represent peaks area.

160

 

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Ripening Time ( Months )

Figure 30. Brittleness, elasticity and gumminess of Domiati

cheese made by conventional and ultrafiltrated methods and
-ripened for 3 months in pouch.

161
ripening. These changes are due to the chemical and
physical changes which cause the body and texture of the
freshly made cheese to lose its firm, tough curdy texture
and to become softer. Elasticity, gumminess and
brittleness of ripened Domiati cheese are plotted in Figure
30. Data indicate that cheese made by the conventional
method possesses greater elasticity than UF-derived cheese.
In both cheeses, young cheese is more elastic than older
cheese. As the data show in Table 118. (Appendixll), fresh
conventional and UF-cheese have less brittleness than 1 and
3 month of ripening.

The changes in the color of ripened Domiati cheese made
by the two methods were measured and the data are presented
in Figure 31. Fresh ultrafiltrated Domiati cheese has
creamer color than conventional cheese. During the cheese
ripening, both cheeses have creamer color as the data reveal

in Table 11C (Appendix 11).

162

 

 

 

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Color changes of fresh and ripened Domiati

cheese made by conventional and ultrafiltration methods.

Figure 31.

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Muslim:

Domiati cheese is the most popular soft cheese in
Egypt. Increasing demand for this type of cheese conflicts
with market shortage of fresh milk. A recent development in
the manufacturing of milk protein products that offers
excellent potential is the ultrafiltration process by which
whey protein can be concentrated, added to milk and
coprecipitated with casein by rennet and heat. Whey
proteins concentrate (WPC), in an undenaturated complex,
contains all of the proteins components in a highly
functional form. Many investigations have shown that this
process improved cheese yield, body and nutritional value.
Additionally, utilization of whey proteins in this way is of
great interest, when considering the saving of natural
resources and solving the problems associated with
pollution.

I This modification has two major advantages for cheese
production in Egypt: First, to produce a cheese with an
inexpensive but balanced protein content, and second, to
find a new outlet for salted whey produced during the
manufacturing of conventional Domiati cheese.

This part of the study was carried out to investigate a
modification of the conventional method of manufacturing

Domiati cheese by supplementing the whole milk with whey

164

165
protein concentrate obtained by ultrafiltration and to
evaluate changes in yield, quality and nutritional value of
Domiati cheese produced by the new process. Component

losses would also be assessed.

WW

Domiati cheese was manufactured by the traditional
procedure as outlined by Mahmmoud ( 1980 ). Whey protein
concentrate ( WPC ) was produced by ultrafiltration of
Domiati cheese whey, as outlined in part 1, to a final
composition of 20.08 % total solids and 8.38 % protein and
used as a supplement to whole milk in individual vats
( Table 43 ). The addition of WPC to milk on a protein
basis ranged from 1:0 for unsupplemented control up to 1:2
for maximal supplementation.

The chemical composition of the mixtures used for
making Domiati cheese is presented in Table 44. The data
reveal that there was a significant increase in total solids
and total protein content up to 28.1% and 10.1 %,
respectively, as the supplementation of the WPC ratio
increased up to 1:2. This relationship indicates a
cumulative effect of whey concentrate addition on protein

content.

mm»
A study of the rennet-induced coagulation time of

cheese milk indicated that the addition of WPC at a 1:1

166

Table 43. Composition of whole milk and whey protein
concentrate used for supplementing the milk

 

Composition (%)

 

Total Protein Fat Lactose Ash Salt

 

solids
Whole Milk 12.18 3.50 3.3 4.80 0.58 0.16
Whey Protein 20.08 8.38 N.D. 5.85 3.89 2.29

Concentrate

 

Data are the means of three determinations.
N.D.= not determined.

167

Table 44. Total solids and protein contents of WPC-
supplemented whole milk mixtures used for making Domiati
cheese

 

Whey protein concentrate-supplemented

 

 

whole milk
Added Total Total
protein solids protein
ratio (%) (%)
1:0.0 12.2 3.5
1:0.25 12.9 3.8
1:0.5 13.4 4.0
1:0.75 14.0 4.6
1:1 14.4 4.9
1:2 15.7 5.7

 

Data are the average of three replications.

168

Table 45. Coagulation time of Domiati cheese made from
whole milk supplemented with different ratios of whey
protein concentrate

 

Milk/ WPC Protein Ratio

 

Coagulation Time ( Min)

 

1:0 1:0.25 1:0.5 1:0.75 1:1

 

74.712 32.011.5 25.311.3 23.0i1.7 21.313

 

Data are means and standard deviations of three
replications.

169
ratio was most appropriate for yielding a firm curd.
Addition of WPC at a still higher concentration ratio up to
1:2, resulted in no coagulation of the mixture at all.
Coagulation times for the various WPC-supplemented milks are
presented in Table 45. Coagulation time decreased from 74.7
min for unsupplemented milk to 21.3 min for whole milk
supplemented with 1:1 protein ratio. These results are in
agreement with those of Rodney et al. ( 1982 ) who found
that setting time decreased as the supplementation ratio
increased. Residual coagulating enzyme in sweet whey may
account for this behavior ( Holmes et al., 1977 ). Recovery
of clotting enzyme from whey by ultrafiltration for reuse in

cheese making was investigated by Castiglioni ( 1969 ).

We“:
The actual yield and yield efficiencies of Domiati

cheese produced from whole milk supplemented at various
levels with WPC are presented in Figure 32. All cheeses
were weighed after draining for 48 hr and the yield
calculated. The weight of added WPC was included as part of
the milk in calculating yields of experimental cheese. The
yield of cheese increased with increasing ratios of protein
concentrate added. The significant increase ( p< 0.05 ) in
actual yield ( direct weight ) of cheese from 17.5 Kg
cheese/100 Kg for unsupplemented milk to 24.8 Kg cheese/ 100
Kg mixture for the 1:0.75 supplementation ratio indicates a

strong potential for improving cheese making

170

 

 

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W Mich Idle

100.00

Yields and yield efficiencies of Domiati cheese
hey protein concentrategsupplemented whole milk.

'Means with the same letters are not significantly

made from w
different at P< 0.05.

a,b,c

Figure 32.

171

efficiency and energy conservation. These results are in
agreement with Abrahamsen's ( 1979 ), who investigated the

possibility of manufacturing semi-hard rennet cheese of
I acceptable quality from milk fortified with different
amounts of WPC by means of ultrafiltration. Walstra and
Jenness (1984) stated the increase in cheese yield was due
to casein-whey protein interaction and greater retention of
moisture.

Cheese yield efficiency is defined as kilograms of
cheese obtained per kilogram of total solids or protein
utilized ( Van Slyke, 1979 ). As the data reveal in Table
12A, ( Appendix 12 ), the yield efficiency changed with the
supplementation ratio, being 1.43 Kg cheese/ Kg total solids
for unsupplemented control cheese and 1.09 Kg cheese/Kg
total solids for cheese produced from maximally supplemented
(1:1) milk. When yield efficiency was based on the total
protein, supplemented cheese (1:0.25 protein ratio) was the
highest yield ( 5.4 Kg cheese/Kg total protein ) over the
entire supplementation. On the other hand, cheese (1:1
protein ratio ) was the lowest (3.4 Kg cheese/Kg protein ).
yield efficiency, which compare control to supplemented
cheese based on unit of protein and total solids, were
significantly different at p< 0.05. The amounts of cheese
solids and protein produced per kilogram total solid and
protein in the control and supplemented cheese were of the

same order as reported by Kosikowski et al.( 1984 ).

172

Table 46. Composition of Domiati cheeses made from whey
protein concentrate-supplementing whole milk using rennet
coagulation

 

 

 

 

Added Cheese Composition (%)
Protein
ratio

Total solids Protein Lactose Fat Ash
1:0.0 44.9‘ 16.3be 2.4° 24.0' 1.6b
1:0.25 46.3” 18.4“ 3.0be 23.0' 1.9b
1:0.5 47.2” 19.0“ 3.5" 22.0' 2.7'b
1:0.75 45.5“ 17.6“ 3.7“ 21.0'ID 3.2'
1:1 39.53cl 14.o° 3.8' 18.5” 3.2'
0,0,0,

QMeans with the same letter are not significant at
P< 0.05.

173
W

The composition of Domiati cheeses produced from whole
milk supplemented with various level of WPC was determined
and presented in Table 46. As the data reveal, there were
significant changes in the characteristics of the
experimental cheeses compared to the control
(unsupplemented) cheese. A significant increase in the
total solids of supplemented cheese at p< 0.05 was observed
as the level of supplementation was increased up to 1:0.75
protein ratio, then rapidly decreased when a higher protein
supplementation ratio (1:1) was employed.

The increase in the total solids and total protein in
the WPC-supplemented cheese was correlated with the increase
in total solids and total protein at various levels of WPC-
supplemented mixtures ( Tables 44 and 46 ). The calculated
results indicated that up to 100.5 protein/protein ratio
high correlation coefficients, rs 0.98 and 0.96 were
obtained between total solids of the produced cheese and the
total solids and total protein of supplemented-mixtures.

On the other hand, lower correlations of 0.95 and 0.92 were

obtained when the total protein of the produced cheese were

correlated to the total solids and total protein in the WPC-
supplemented mixtures. At supplementation ratios of 1:0.75

and 1:1, no positive correlation was observed.

There were significant increases in lactose and ash
content in the cheese as the protein supplementation ratio

increased up to 1:1. On the other hand, percentage of fat

174

decreased significantly ( p< 0.05 ) as supplementation was
increased. These result are in agreement with El-Shibiny et
al.( 1973 ) who added heat precipitated whey protein to the
milk for making Domiati cheese. The results for protein and
fat content showed the same trend as observed by Brown et
al.( 1982 ) who produced cheddar cheese from WPC-
supplemented milk and by Wes ( 1980 ) who manufactured low-
fat Gouda-type cheese by addition of WPC to the milk.

Protein fractions of Domiati cheese made from WPC-
supplemented whole milk were studied and the data presented
in Figure 33. The data in Table 123 (Appendix 12) revealed
no significant differences at p< 0.01 between the amount of
casein in the experimental and control (unsupplemented)
cheeses except in the case of 1:1 supplemented ratio. The
amount of non-casein protein (NCN) significantly increased
with increasing supplementation up to 1:0.75 protein ratio.
The amount of whey protein (WP) increased significantly from
0.71% for unsupplemented cheese to 2.4 % and 2.0 % for
supplementation ratio of 1:0.5 and 1:0.75, respectively.
These results are consistent with the findings of Abrahamsen
( 1979 ). There was a high correlation ( 0.83 ) between the
amount of protein in the milk mixtures and the protein
present in the cheese for supplementation ratios up to 1:0.5
protein ratio.

The nutritional quality of the cheeses was indicated by

the amount of essential and non-essential amino acids

175

 

 

D.
W
n .Heponehonoponehonowonehonouououonon.

 

7”]
'H-K

no“onenoueweneueuononeuonohOHOHOHOHOHOUOHOHO
r”’1

....-h.
.Honouenouonouohouohouohonehououonououohenohene
7”].

.n-p‘

.nehonououoweue Homewo“oven.“onoheneuouehonohon
ll

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a.“33.8.8333”!.onnzxkzowvvx

 

3 2288.1 539...

1: .75 1:1.00

.50

1:

1: .25

.00

1:

. Milk/WPC Protein Ratio
Protein fractions of Domiati cheese made from whey

NCN: non-casein

nitrogen, NPN: non-protein nitrogen, and WP: whey protein.

protein concentrate-supplemented whole milk.

Figure 33 .

176

Table 47. Quantitative changes of total amino acids of
Domiati cheese made from whey protein concentrate-
supplemented whole milk

 

Amino Acids Milk/WPC Protein Ratio

 

 

 

 

Control 1:0.25 1:0.5 1:0.75 1:1
(9/1009 )

Asp 0.96 1.10 1.00 1.00 0.60
Glu 2.10 2.20 2.00 1.90 1.70
Ser 0.93 1.00 0.95 0.95 0.70
Gly 0.43 0.46 0.50 0.50 0.40
His 0.35 0.44 0.50 0.55 0.40
Arg 1.85 1.75 1.50 1.45 1.23
Thr 0.71 0.94 1.10 1.12 0.80
Ala 0.64 0.73 0.73 0.68 0.66
Pro 1.71 1.32 1.20 1.00 1.00
Tyr 1.14 1.00 0.98 0.80 0.80
Val 1.45 1.49 1.52 1.48 1.40
Heth 0.43 0.80 1.10 1.00 0.40
Cys 0.20 0.49 0.65 0.60 0.20
Ile 0.65 0.84 1.00 0.80 0.40
Leu 1.08 1.53 1.70 1.50 0.90
Phe 0.60 0.55 0.45 0.40 0.40
Lys 1.30 1.60 1.85 1.50 0.90
IQ§§1_A‘A 16.53 18.34 18.73 17.23 12.89

 

The data are the average of three determinations.

177

Table 48. Quantitative changes of free fatty acids of fresh
Domiati cheese made from whey protein concentrate-
supplemented whole milk

 

 

 

 

Free Milk/WPC Protein Ratio
Fatty
Control 1:0.25 1:0.5 1:0.75 1:1
mg/lOOg
C4:0 3.9 3.5 3.1 2.8 2.5
C6:0 4.1 3.7 3.5 3.3 3.1
C8:0 5.1 4.7 4.3 3.9 3.0
C10:0 4.4 3.8 3.7 3.4 3.1
C12:0 4.6 4.2 3.6 3.5 3.0
C14:0 11.7 9.3 8.6 8.5 8.2
C16:0 34.1 24.6 23.8 22.0 21.0
C18:0 10.2 9.3 8.7 7.7 6.9
C18:1 28.1 25.0 20.5 19.0 17.6
C18:2 5.2 4.6 3.6 3.4 3.1
C18:3 1.8 1.7 1.5 1.1 0.6
IQ§§1_££A 113.14 93.9 84.72 78.56 72.32

 

The data are the average of three determinations.

178
presented. Total amino acids found in the experimental
Domiati cheese are summarized in Table 47. Generally, the
total quantity of amino acids increased with increasing
addition of whey protein to the milk up to 1:0.75 protein
ratio. The highest increase of essential amino acids was
28.2 % for 1:0.25 protein ratio and 45.79 % for the 1:0.5
protein ratio when compared to the control.

Fresh control and Domiati cheese made from whole milk
supplemented with WPC were analyzed for free fatty acids.
The results are presented in Table 48. Control cheese
contained a higher concentration of free fatty acids than
cheese made from whey-supplemented milk. All the fatty
acids showed a similar decreasing pattern, as
supplementation was increased. Total free fatty acids were
113.14 mg/lOOg for the unsupplemented cheese, decreasing to
93.9, 84.72, 78.56 and 72.32 mg/lOOg for supplementation
ratios of 1:0.25, 1:0.5, 1:0.75 and 1:1 protein ratio,
respectively. These results show a trend similar to fat

content decrease in the WPC-supplemented cheeses (Table 46).

99.100.03.413!

UF-whey, which possesses protein in an undenaturated
form, was used as a supplement to cheese milk to improve
cheese quality. Sensory evaluations of whey-supplemented

cheese for flavor, texture/body, and color are presented

179

Table 49. Organoleptic properties of fresh Domiati Cheese
made from whey protein concentrate-supplemented whole milk

 

 

 

Properties Milk/WPC Protein Ratio

Control 1:0.25 1:0.5 1:0.75 1:1
Flavor 28.5 29.0 29.7 21.7 18.0
Texture/Body 56.0 57.0 59.0 42.0 32.0
Color 10.0 9.5 9.1 8.0 6.7
Total 94.5 95.5 97.8 71.7 56.7

 

Body and Texture, 60 = Excellent.
Flavor, 30 = Excellent.
Color, 10 - Excellent.

180
in Table 49. The cheese produced from whole milk
supplemented with WPC to a ratio of 1:0.5 attained the
highest quality score ( 97.8 ). On the other hand, quality
scores decreased to 71.7 and 56.7 for supplementation of
1:0.75 and 1:1 protein ratio, respectively. The most
prominent defects in the WPC-supplemented whole milk cheese
were a slight bitter flavor, weak and pasty body, and a

creamier color in the high supplementation ratio cheeses.

92122

The color parameters L, a, and b were measured in WPC-
supplemented cheese and are presented in Figure 34.
Whiteness, variable L, showed a significant difference at
p<0.05 between the different supplementation ratios of
fresh cheese. It was 96.8 for control cheeses and decreased
with increasing supplementation ratios, to 90.0, 84.8, 80.1
and 74.0 for ratios of 1:0.25, 1:0.5, 1:0.75, and 1:1,
respectively. The correlation of variable L with the
sensory color was highly significant ( r 80.96 ).
Supplemented cheese show slightly creamer color as the
addition of whey protein concentrate was increased.

While greenness (-a) and yellowness (b) showed
significant increase with increasing supplementation as

presented in Table 12C (Appendix 12).

181

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

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ame letters are not significantly

Color changes of Domiati cheese made from whey
pplemented whole milk.

otein concentrate-su
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different at P< 0.05.

Figure 34.
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182

W

A texture profile method for hardness, cohesiveness,
adhesiveness, gumminess and elasticity was proposed by
Brandt et al. (1963) as a means of aiding the food
researcher to obtain descriptive characteristics of food.
Typical force distance profiles obtained from the control
cheese and cheese made from whole milk supplemented with WPC
at various levels are illustrated in Figure 35.

Cheese samples were tested for their mechanical
properties by a compression test at 80 % deformation. The
data indicate that there were significant difference in the
area and height of the first and second bite of control
cheese and the cheese made from milk supplemented with WPC.
The calculated data concerning hardness, cohesiveness,
chewiness, gumminess, adhesiveness and elasticity are
summarized in Figures 36, 37 and 38. It can be seen that,
there were significant differences ( p< 0.05 ) between
Domiati cheese produced from milk only ( control ) and
cheese produced from milk supplemented with WPC at various
levels. As the supplementation ratio increased, the
firmness of the cheese decreased and became less firm.
These results were consistent with the findings of
Abrahamsen ( 1979 ) and Brown ( 1982 ) who stated that the
higher moisture in WPC-supplemented cheese could account for
the slight increase in pastiness and decrease in curdiness.

A slight resistance of the curd during the press step,

183

 

 

Figure 35. Texture profile curves of Domiati cheese made from
whey protein concentrate-supplemented whole milk. Curves
obtained with the Instron Universal Testing Machine.
Hardness: height of A" cohesiveness: , and Adhesiveness:
A3. Milk/ WPC protein ratio: l=contro , 2=1:o.25, =1:o.s,

4=130.75 and 5:131.

184

 

 

 
 
 

   

      

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Milk/WPC Protein Ratio

Hardness and cohesiveness of Domiati cheese made
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N: Hewtons.

different at P< 0.05.

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Figure 37. Chewiness and gumminess of Domiati cheese made
fgim whey protein concentrate supplemented whole milk.

" eans with the same letters are not significantly
different at P< 0.05. H: Newtons.

 

186

 

 

 
   

             
 
 

 
 

   
     

            
 

  
 

   
 
  

   

                             
 
 
 

 
           

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Milk/WPC Protein Ratio
Elasticity and brittleness of Domiati cheese

from whet protein concentrate-supplemented whole milk.

eans with the same letters are not significantly

de
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different at P< 0.01. H: Newtons.

2

Figure 38.

187
presumably an to effect of the whey proteins, resulted in a

tendency toward more open and crumbly cheese.

mm

The proteins of the cheeses made in this work, were
subjected to electrophoresis. The densitograms resulting
from scanning the electrophoretic gels of control and WPC-
supplemented cheeses are illustrated in Figure 39. To aid
in the identification of protein components in the
electrophoretic pattern of cheese, known protein fractions
were subjected to Disc PAGE at the same time. The main
visible protein bands were identified as a- and B-casein,
a-lactalbumin and B-lactoglobulin. Comparing the pattern of
control cheese and WPC-supplemented cheese revealed a
decrease in the relative peak areas of a-casein and p-casein
as the addition of WPC increased. On the other hand, The
peak area of a-lactalbumin increased as the proportion of
WPC added to the whole milk increased. The peak area of 0-
lactoglobulin also increased with rising supplementation.
The mobilities of p-casein and fi-lactoglobulin are similar.
Thus, the overlap of fi-lactoglobulin and fi-casein account
for the increased peak area as a result of the accumulation
of WPC. Comparison of PAS patterns from various WPC-
supplemented cheeses revealed substantial differences in the
number of bands in each of individual zone. These result is

due to the interaction of whey protein and casein micelles

188
when heated together, they complex with each other primarily
through intermolecular S-S bonds between fi-lactoglobulin and

k-casein ( Smits and Van Brouwershaven 1980 ).

zhsz_semeenenta
The mean composition of whey obtained at the end of the

draining step during the manufacturing of control Domiati
cheese and WPC-supplemented cheese with various levels of
whey protein supplementation was studied and the data are
presented in Figure 40. As the supplementation ratio
increased in the whole milk mixtures, the loss of total
solids, protein and ash in the drained whey increased.

As the data reveal, total solids ranged from 6.37 %

( unsupplemented control ), to 9.0 % ( maximal
supplementation). Protein in the drained whey ranged from
1.1 to 3.2 t, and ash from 0.39 to 1.55 %, respectively.

 

 

Figure 39. Discontinuous polyacrylamide gel electrophoresis
densitograms of Domiati cheese made from WPC supplemented
whole milk. A: a-casein B: p-lactoglobulin & p-casein, c: a-
lactalbumin. Milk/ WPC protein ratio: l=control, 2:1:o.25,
3:1:0.5, 4:1:0.75 and 5:1:1.

189

190

 

 

444

44.44 444444444444444444444444444444444444444444444444444

                         

V\\.\\.

1:1.00

Cu.“...”.H.n.n.u.n.u.n.u.n.n.n.u.

V\\\.

0.75

Milk/WPC Protein Ratio
Figure 40. Components of whey from Domiati cheese made from

UH.”.u.u.u.u.n.H.H.H.n.n.u.na .l

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1 :0.50

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A5 5202.030

WPC supplemented whaie milk.

CONCLUSIONS

Ultrafiltration technology is widely accepted as a
preconcentrating step in cheese making and used commercially
for manufacturing many cheese varieties all over the world.
UF can be envisioned as a routine process in many dairy
plants of the future.

The technical feasibility of direct ultrafiltration in
the manufacture of Egyptian soft-white "Domiati" cheese has
been successfully demonstrated.

A spiral wound membrane with a cut off of 5,000 Daltons
was used to concentrate and fractionate whole milk, skim
milk and sweet whey using ultrafiltration (UF)and
diafiltration (DF)processes.

Retentate produced by DF was higher in protein whereas
the retentate formed by UF contained more total solids.
Electrophoretic studies showed that fi-lactoglobulin was the
major whey protein in UP and DF retentates. Of the 19
minerals analyzed, Ca, Mg, K , P, Cu and Fe were higher in
the retentate than in the permeates from whole milk, skim
milk and whey. Complete retention of the fat phase was
obtained by UF and DE. The free fatty acid (FFA) content,
with the exception of some short-chain ones, increased with

the degree of concentration by UP and DF. Whey protein

192
concentrate was richer in essential amino acids than that of
total milk protein or casein. Also, the permeation rate
decreased as the degree of concentration increased during UP
and DF.

Fresh Egyptian soft-white "Domiati" cheese made from
ultra/diefiltration-whole milk retentate, using the MMV
technique, was compared to fresh cheese made from whole milk
produced conventionally. Nitrogen values and fractions
representing total protein, non-casein nitrogen, total
albumin and soluble nitrogen of UF-derived cheese were
higher (p<0.05) than the corresponding fractions of
conventionally prepared cheese. Electrophoretic patterns of
protein extracted from fresh UF-cheese confirmed the
presence of a higher content of a-lactalbumin and B-
lactoglobulin than found in conventional cheese. There was
a higher concentration of free fatty acids and free amino
acids in UF-cheese than in conventional cheese. Texture
characteristics of fresh UF and conventional Domiati cheese
showed significant differences (p<0.05) with regard to
hardness, cohesiveness, chewiness, gumminess, adhesiveness
and elasticity. The UF-cheese was harder and more adhesive
than conventional cheese, whereas conventional cheese was
characterized by more pronounced chewiness and gumminess
than UF-cheese. The sensory evaluation of flavor, body/
texture and color by a panel of judges also indicated that
fresh UF-cheese was more uniform and creamy than

conventional cheese.

193

Also, retentate produced by UF/DF whole milk was
freeze-dried and stored. Dried retentate was reconstituted
with warm water, for manufacturing ”Domiati" cheese,
utilizing the MMV method which gave a curd in 10 min.

Cheese was ripened by two methods: 1) packed in
polyethylene-lined aluminum pouches sealed under vacuum and,
ii) in plastic containers with 8% brine. The packed
cheeses were ripened at 7°C for eight weeks.

Vacuum treatment produced cheese with close texture and
smooth surface, which aid in preventing mold growth and
spoilage.

Pouch and brine ripened cheeses ( 4, 6 and 8 weeks)
showed significant increases in total solids, fat, ash and
protein (p< 0.05) as compared to fresh cheese. Statistical
comparisons of the two ripening methods at 2, 4, 6 and 8
weeks of ripening showed that pouch-cheese had more protein,
fat, sugar and ash than cheese ripened in brine.

The increase in the non-casein nitrogen, non-protein
nitrogen and ripening index of pouch cheese was more
pronounced than in brine cheese throughout the ripening
period. After two months of ripening, the liberation of
free fatty acids as well as free amino acids was higher in
pouch cheese than in brine cheese.

These differences between the two ripening procedures
were related mostly to hardness, cohesiveness and gumminess
of the cheese, which were significantly higher for pouch-

ripened cheese than brine-ripened cheese as indicated from

194
the sensory evaluation scores.

Pouch-cheese ripened in the absence of brine were
generally attractive, uniform and creamy in color, firm in
body, possessing a waxy, buttery-smooth texture and a
pleasant flavor. This new method for ripening Domiati
cheese in vacuum pouches resulted in improved cheese yields
and an acceleration of cheese ripening. Finally, the
efficiency of the ripening methods was monitored by
measuring the actual loss of fat and protein in the serum
produced from pouch- and brine- ripened cheese.

Vacuum pouch-ripened cheese produced by ultrafiltrate
and conventional procedures and ripened for three months at
10°C showed significant differences in gross composition
with higher values for UF-cheese. After three months of
ripening, the increase in ripening indices, free amino acids
and free fatty acids was more pronounced in UF-cheese than
in conventional cheese. Electrophoretic patterns of the two
cheeses confirmed that protein degradation occurred more
extensively in UF-cheese than in conventional cheese.

Color and textural qualities in ripened UP and
conventional cheese showed a significant difference (p<0.05)
as compared to their fresh counterpart. Both cheeses
increased in hardness, cohesiveness and gumminess after one
month, followed by a decrease after three months of
ripening. While young cheese exhibited more elasticity than
aged cheese, the conventional cheese possessed greater

elasticity than the UF-cheese.

195

The technical feasibility of using ultrafiltration
indirectly in the manufacture of Domiati cheese through
supplementation of whey protein concentrate (20 0 total
solids and 8.38 % protein) has been successfully
demonstrated.

Small vat trials were conducted on Domiati cheese made
from cheese milks supplemented with whey protein concentrate
at protein/protein ratio 1:0 1:0.25, 1:0.5, 1:0.75, 1:1 and
1:2 to determine critical processing parameters. The
addition of WPC to the whole milk produced a significant
increase (P<0.05) in total solids and protein, from 12.5%
and 3.5% up to 28.1 and 10.1 % respectively. Reduction in
coagulation time was observed as supplementation level with
WPC increased with a demonstrated dramatic increase in yield
(p<0.05). There was also a significant increase in total
solids, lactose and ash, non-casein protein and whey protein
as the protein supplementation increased up to 1:0.75. On
the other hand, the percentage of fat decreased
significantly as supplementation was increased. The
electrophoretic patterns of WPC-supplemented cheese
indicated a decrease in the peak areas corresponding to a-
casein and fi-casein, when compared to those of control
cheese. On the other hand, a-lactalbumin and fi-
lactoglobulin in WPC-supplemented cheese increased with the
amount of WPC added. There was an increase in essential and
nonessential amino acids as the addition of WPC increased.

Whey protein concentrate-supplemented cheese with 1:0.25 and

196
1:0.5 protein ratios attained the highest scores for flavor,
texture/body and color. However these scores decreased as
the supplementation level was increased to higher levels.
Whiteness value (L) indicated a significant decrease in
color, while greenness and yellowness (-a) and (b) showed
significant increases with supplementation. .The mechanical
properties of cheese revealed that there were significant
differences (P<0.05) between Domiati cheese produced from
unsupplemented milk and that produced with various levels of
supplementation. In regard to whey drained during cheese
manufacture, as the level of WPC increased in the milk
mixtures, the loss of total solids, protein and ash in the
whey increased from 6.37%, 1.1% and 0.39% to 9%, 3.2% and

1.55%, respectively.

FUTURE RESEARCH

The investigation into the manufacture of Domiati
cheese by supplementing the whole milk with WPC obtained by
ultrafiltration raised questions which merit further study:
1- Run experiments on the ripening of Domiati cheese made
from WPC-supplemented whole milk.

2- In order to minimize losses in the cheese whey, the
following should be tried:

a) Acid coagulation of the WPC-supplemented whole milk,
without rennet. Acid could be added as glocono-
delta-lactone or developed by lactic acid starters.

b) Acid and heat coagulation. Since heat may destroy the
ripening microorganisms and enzymes, either lipase or
protease should be added to the curd.

3- To gain all the benefit of ultrafiltration of milk and
whey. Another experiment should be carried out in which
WPC would be added to whole milk preconcentrated by
ultrafiltration (milk retentate).

4- Further studies need to be conducted to investigate these
different processes comparatively from the economic

standpoint.

197

APPENDICES

199

Appendix (1)

WW
1- Running gel buffer,pH 8.9,0.380 M Tris HCL as prepared

by dissolving 4.6018 g Tris (hydroxymethyl) aminomethane in
about 95.0 mL distilled water: 42.0 g of urea were added to
make the buffer 7 M. The pH was adjusted to 8.9 with
concentrated HCL and the volume was made to 100.0 mL with
distilled water.

2- Stacking gel buffer,pH 6.7, 0.062 M Tris-HCL,7 M urea ,
was prepared by dissolving 0.7508 g of Tris in about 95.0 mL
distilled water :42.0 g of urea were added to make the
buffer 7 H. The pH was adjusted to 6.7 with concentrated
HCL and volume made to 100.0 ml with distilled water. 3-
Electrode buffer,pH 8.3,.046 M Tris glycine,was prepared

by dissolving 16.71 g of Tris in about 2100 mL distilled
water. The pH was adjusted to 8.3 with 2 M glycine solution
and the volume was made to 3000 mL with distilled water.
4-Running gel solution, 25 %(w/v) acrylamide solution, was
prepared by dissolving 24.83 g of acrylamide monomer and
0.64 g of NN- Methylenebisacrylamide (BIS) in 75 mL of the
running gel buffer and making it to 100 mL with the same
buffer. This provided a stock solution with 25 % total
acrylamide.

5-Stacking ge1 solution,6.25 % (w/v) acrylamide solution ,

200
was prepared by dissolving 5 g of acrylamide monomer and
1.25 g of BIS in 75mL of the stacking ge1 buffer and making
it to 100 mL with the same buffer.
6-Ammonium persulfate solution ,5%(w/v) 7 M urea,was
prepared by adding 0.625 g ammonium persulfate and 5.25 g
urea in 12.5 mL of distilled water. The solution was
prepared every two days.
7- N,N,N,N- tetramethylethylene diamine (TEMED).
8-Bromophenol blue ,1% (w/v) solution was made using
stacking gel buffer.
9-Saturated sucrose solution was made using gel buffer.
10-Staining solution :it contained 25 % (v/v) isopropanol,10
%(w/v) acetic acid and 0.05 % (w/v) Comassie brilliant blue
R-250 in distilled water.
11 - pestaining solution: 5 % (v/v) acetic acid and 10 %

(v/v) Isopropanol in distilled water.

Marines.
1-The dry tubes were marked with a felt-tip pen at distances

10.0 and 11.6 cm from the bottom.

2-The bottom of each tube was fitted with a small square of
parafilm. Tubes were then placed in a leveled rack.

3-A gel solution of the desired concentration (9%) was
prepared by combining 9 mL of running gel solution and 15.7
mL running gel buffer to give a final volume of 24.7 mL.

4- To this gel solution , 20 uL of TEMED and 0.3 mL of

201
ammonium persulfate solution were added.
5-The gel solution was transferred to the glass tubes with a
syringe fitted with an 18 gauge needle. Each tube was filled
to the 10.0 cm mark , carefully overlayered with distilled
water,and allowed to polymerize overnight.
6-After polymerization of the running gel,the water layer
was removed and the top of the running gel was rinsed with
stacking gel buffer. The buffer was removed from the running
gel.
7-The stacking gel was prepared by mixing 5.0 mL of the
stacking gel solution with 1 g sucrose. The volume of the
solution was made to 10.0 mL with stacking gel buffer; 40
uL of ammonium persulfate and 10 ul of TEMED were added.
8-Each tube was filled to the 11.6 cm mark with stacking
gel, overlayered with water ,and allowed to polymerized for

one hr.

202

APPENDIX (2)

Amino Acid Analysis

we a

30 uL of standard and hydrolyzed amino acid samples
were placed in a reaction vial, 10 uL of internal standard
was added to each vial. Put the vials into the Millipore
reaction vessel and connect to work station, slowly turn on
vacuum and allow to dry completely. 20 uL of redryinq
solution consisting of ethanol:Na acetate:triethylamine
(2:2:1) was added with gentle shaking and installed into the
work station until dry.

Phenylthiocarbamate (PTC)-amino acids were formed by
adding 20 uL of fresh derivative reagent consisting of
ethanol: triethylamine (TEA): water: phenylisothiocyanate
(PITC) 7:1:1:1 to the dried samples and incubated for 20
min. at room temperature to complete the reaction between
the free amino acid and the PITC. Vials was washed with 10
uL of methanol: methanol: Hg: (50:50): methanol in
sequential order and dried to drive off excess PITC. 200
uL of diluent was added to each sample, pipetted into
volume restriction inserts. Fifteen to 30 uL in volume were
analyzed using a reverse phase HPLC model ALC 204 Liquid
chromatograph ( Water Assoc.) which consisted of two solvent
delivery systems, model M440, and a sample auto-injector,

Model M710B. Amino acids were separated by a 15 cm x 3.9 mm

203
pica-Tag analytical column. The solvent system consisted of
(A) an aqueous buffer and (B) 60% acetonitrile in water.
The buffer was 0.14 M sodium acetate containing 0.5 ml TEA/L

of Na acetate solution.

Operating Parameters
Absorption.

204

APPENDIX (3)

Mineral Analysis

for Mineral Analysis by Atomic

 

Argon Gas Flow:
Sample:

R.F. Power:
Integration Time:

Observation Height:

Sample Uptake:

Wavelengths (A°)

Ca 3706.00
Fe 2599.40
Pb 2203.53
Zn 2138.56
Mn 2576.10
AI 2020.30
Cu 3082.15
Se 1960.26

CO 2286.16

Coolant: 18 L/min.
Auxiliary: 1 L/min.
0.5 L/min.
Incident: 1.1 KW
Reflected: < 5W

Two 4 sec observations with one
4 sec background correction.

15 mm above top work coil.

Peristaltic pump at 1.5 ml/min.

Na 3302.98
9 2149.14
Mg 2790.79
K 4044.14
TI 1908.64
Hg 1942.27
Cd 2288.02
Cr 3247.54

 

205

Appendix (4)

Table 4A. Rate and volume of permeate derived from whole
milk by diafiltration process

 

 

Permeate removed Concentration Permeate Flux
(% of milk ) factor thF /hr

0.0 1.0 36.1

8.3 1.1 27.8

33.3 1.5 22.8

66.7 3.0 18.5

72.2 2.0 19.4

83.3 2.7 25.9
100.0 4.0 17.2
113.0 4.5 5.9

 

The data represent average of three determinations.

206

Table 48. Rate and volume of permeate derived from whole
milk by ultrafiltration

 

 

Permeate removed Concentration Permeate Flux
(a; of milk ) factor L/m2 /hr

0.0 1.0 36.9

13.0 1.1 30.4

33.3 1.5 27.2

66.7 , 2.5 23.2

79.9 4.1 11.1

80.3 4.8 9.1

 

The data represent average of three determinations.

207

Table 4C. Rate and volume of permeate derived from Skim
milk by ultrafiltration

 

Permeate removed Concentration permeate flux

 

( % of milk ) factor (L/mZ/hr)
0.0 1.0 50.0
7.4 1.1 41.0

21.1 1.3 35.0

40.0 1.7 31.0

58.0 2.4 29.0

72.0 3.5 25.5

82.0 4.2 18.3

 

Values are the average of three determinations.

208

Table 4D. Rate and volume of permeate derived from whey
by ultrafiltration

 

 

Permeate removed Concentration Flux (permeate
rate)
(% of milk) factor ( L/mz/hr)

0.0 1.0 78.0

13.0 1.2 71.0

33.3 1.5 45.0

56.0 2.6 36.0

73.0 3.7 31.0

83.0 6.0 27.0

 

The data represent the average of three determinations.

209

Appendix (5)

Table 5A. Change in retentate composition during
diafiltration of whole milk

 

 

 

 

Permeate Composition (%)
removed .
(% of milk) VCR Total Ash Protein Lactose Fat
solids

g/100 g
0.0 1.0 12.2 0.8 3.1 5.0 3.4
8.3 1.1 12.7 0.9 3.6 4.5 3.8
33.3 1.5 18.0 0.9 7.6 4.2 6.0
66.7 3.0 23.9 1.2 8.5 4.1 10.2
72.2 2.0 17.2 0.8 6.8 2.2 7.5
83.3 2.7 19.2 0.9 . 7.6 2.1 8.5
100.0 4.0 26.0 1.2 8.6 2.0 14.5
113.0 4.5 32.6 1.5 13.6 1.9 15.5
(CF) 2.7 2.0 4.47 0.39 4.5

 

avolume concentration ratio represent the percent weight of
the retentate to the original milk weight.

Values are the average of three determinations.

210

Table 5B. Change in retentate composition during
ultrafiltration of whole milk

 

 

 

Permeate Composition (%)

removed VCR‘

(% of milk) Total Ash protein Lactose Fat
0.0 1.0- 12.3 0.7 3.3 4.9 3.4
13.0 1.1 14.1 0.9 3.8 5.3 3.9
33.3 1.5 18.2 1.1 5.2 5.7 6.2
60.7 2.5 24.9 1.5 6.4 6.5 9.9
78.9 4.1 32.2 2.7 8.5 6.8 14.2
80.3 4.8 38.4 3.5 10.5 7.9 16.5
(CF) 3.12 4.7 3.23 1.6 4.8

 

‘volume concentration ratio represent the percent weight of
the retentate to the original milk weight.

The data represent average of three determinations.

211

Table 5C. Change in retentate composition during
ultrafiltration of skim milk

 

 

 

permeate . Composition (%)
removed VCR
(% ofmilk)
Total Ash Protein Lactose
solids
0.0 1.0 8.8 0.8 3.0 5.0
7.4 1.1 9.5 0.9 3.3 5.1
21.1 1.3 10.9 1.2 4.6 5.1
40.0 1.7 13.0 1.5 6.3 5.3
58.0 2.4 15.1 1.9 7.9 5.4
72.0 3.6 17.0 2.3 8.6 6.0
82.0 4.2 19.5 2.6 10.0 6.9
(CF) 2.2 3.4 3.33 1.4

 

'volume concentration ratio represent the percent weight of
the retentate to the original milk weight.

Values are the average of three determination.

212

Table 5D. Changes in retentate composition during
ultrafiltration of whey

 

Permeate
removed
(%of milk) VCRa

Composition (%)

 

 

Total Protein Ash Lactose

solids
0.00 1.00 6.6 1.1 0.5 5.0
13.0 1.15 6.7 1.3 0.5 5.2
33.3 1.50 7.8 1.8 0.6 5.4
56.7 2.60 9.0 2.7 0.9 5.7
73.3 4.10 13.0 5.4 1.1 6.5
83.0 6.00 15.7 7.1 1.6 7.0
(CF) 2.4 6.1 3.4 1.4

 

'volume concentration ratio represent the percent weight of
the retentate to the original milk weight.

Values are the average of three determination.

Table 6A.

213

Appendix (6)

ultrafiltration of whole milk

Changes in permeate composition during

 

Permeate
removed

( % Of milk )

Composition ( % )

 

 

Total Lactose Protein Ash
13.03 5.22 4.8 0.09 0.33
33.32 5.28 4.9 0.12 0.36
60.66 5.8 5.1 0.2 0.4
79.97 6.83 6.1 0.31 0.42
80.3 7.4 6.5 0.4 0.49
Average 6.1 5.48 0.224 0.4

 

Values are the average of three determinations.
Protein expressed by (N x 6.38).

214

Table 6B. Changes in permeate composition during
diafiltration of whole milk

 

 

 

Permeate Composition (%)

removed

(% of milk) Total Protein Lactose Ash

solids

8.3 5.35 0.04 5.0 0.31
33.3 5.83 0.09 5.4 0.34
66.6 6.52 0.15 6.0 0.37
72.2 2.85 0.10 2.5 0.24
83.3 2.58 0.12 2.2 0.25
100.0 2.51 0.18 1.99 0.33
113.0 3.00 0.21 2.40 0.39
Average 4.10 0.127 3.64 0.318

 

The data is average of three determinations.

Protein expressed by (N x 6.38).

215

Appendix (7)

Table 7A. Percent recovery and response factor of individual
fatty acids

 

 

 

 

Fatty Concentrations Recovery Response
Acids ' - ( % ) Factorb
Added Recovered
mg/g

C4:O 55 44.6 81 1.17:0.6
C6:0 43 42.7 99 0.96:0.4
c7:o 1.0b
C8:0 41 41.94 102 1.0310.5
010:0 43 44.9 104 1.04:0.2
C12:0 ~ 68 69.2 102 0.91:0.3
C14:0 113 115.2 102 0.95:0.4
C16:0 131 136.1 104 l.03iO.3
017:0 1:0b
C18:0 91 91.9 101 1.05:0.5
C18:1 200 209.9 105 0.99:0.6
C18:2 50 49.3 99 0.9810.8
C18:3 50 46.9 94 0.89:1.0

 

Means and standard deviations of three replications.
§Assigned.

216

21?!

NO Q

can: 1: 9’ ‘9" ‘fi
“ i

 

 

(310
(312
#616

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3 3
3
Wm
\ ;
i0 20 30 4o 50 on:

Retention time (min)

Figure 7A. Typical gas chromatogram of the standard free
fatty acids (on 10 % 8P-216-PS on 100/120 Supelcoport).

217

Appendix (8)

Table 8A. Peak areas and their distribution in whole
milk,casein and TAN during ultrafiltration process

 

. Peak area Distributionb
Time

 

(a-Cn) (a-La) (fi'Cn+fi'L9) (a-Cn) (a-La) (fi-Cn+B-Lg)

 

 

 

 

 

Milk
1 301680 24464 222695 55.0: 4.46% 40.6%
2 483315 26267 365988 55.2 : 3.0: 41.8%
3 1418943 74301 1086653 55.04 2.88% 42.12%
p-Cn a-Cn fi-Cn a-Cn
£03910
1 207813 295323 41% 59%
2 427849 608372 41: 59:
3 783635 1189398 41% 59%
B-Lg a-La fi-Lq a-La
Tetal_alhumin_nitressa
1 96501 28000 77.5% 22.4:
2 327163 70607 82.2% 17.8%
3 521659 100846 83.8% 16.2%

 

aTime :l-original, 2-half time run, 3-final run.

ercent of total areas.

a-Cn= a-Casein, fi-Cn: fi-Casein, a-La= a-Lactalbumin and
fi-Lg- p-Lactoglobulin.

218

Table 8B. Peaks area and their distribution in skim milk
during ultrafiltration'

 

 

 

 

 

 

Peak area Distributionb
Time'
a-Cn B-Cn a-Cn fl-Cn
9.35510
1 607807 395145 60.4% 39.6%
2 738168 477410 60.7% 39.3%
3 1714774 1014318 62.8% 37.2%
fi-Lg a-La a-Lg a-La
Witness
1 68702 21565 76.1% 23.89%
2 206316 48081 81.1% 18.9%
3 257319 55341 82.3% 17.7%

 

:Time :1-origina1, 2-half time run, 3-final run.
Percent of total areas.

Table 8C. Peak areas and their distribution in whey during

ultrafiltration process

219

 

 

 

 

Peak area Distribution”
Time“
fi-Lg a-La fi-Lg a-La
1 26711 8435 76.0% 24.0%
2 383697 40899 87.4% 12.6%
3 515196 61568 88.7% 10.6%
4 616845 67019 90.2% 9.80%

 

“Times: 1: original, 2: 15 min, 3: 30 min and 4: 60 min.

ercent of total area.

 

220

Appendix (9)

 

 

 

 

 

 

 

Name Sample 4 Date
Flavor

Excellent Very Good Average Lacks Flavor
Body

Very Hard Firm Good Weak Very Weak
Texture

Very Smooth Smooth Sl.Mealy Very Mealy
Color

Excessive Good Lacks Color

Figure 9A. Domiati Cheese Score Card used to evaluate the
quality of Domiati Cheese.

221

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222

Table 108. Nitrogen fractions of Domiati cheese made from
reconstituted ultrafiltrated whole milk ripened in pouches
and 8% brine solution for 8 weeks.

 

Pouch 8% brine

 

Nitrogen fraction

 

 

Ripening

time

(Week) TP NCN NPN TP NCN NPN

0 12.55 2.31 1.02 12.55 2.31 1.02
2 13.24 2.63 1.50 12.30 1.89 1.15
4 13.50 2.80 1.72 12.50 1.95 1.43
5 14.60“' 3.05 1.90 12.79 2.10 1.40
8 15.30” 3.37‘ 2.20 13.00 2.22 1.48

 

Means within a column are significantly different at

*, p < 0.05 and **, P< 0.01 from fresh (0 time).

Standard error for TP, NCN, NPN are 0.4, 0.3 and 0.32 for
pouches cheese; 0.22, 0.17 and 0.3 for cheese ripened in 8
% br ne.

223

Table 10C. Texture profile analysis of Domiati cheese made
from reconstituted ultrafiltrated whole milk and ripened in
pouches for 8 weeks

 

 

 

Ripening Time (Weeks) Standard
error
0 2 4 8
M2035
Hardness 3.85 5.77‘ 8.33" 9.85" 0.44
Cohesiveness 0.63 0.52 0.65 0.74 0.10
Chewiness 5 . 09 5 . 91' 10 . 0” 12 . 39" o . 38
Gumminess 2.21 2.92 3.88’ 6.21” 0.38
Elasticity 2.10 1.97 1.85 1.70 0.11

 

Sample with the same row are significantly differ at * p,
<0.05 and **, p<0.01 from fresh (0 time ).
Values are means and standard errors of three replications.

224

Table 10D. Texture profile analysis of Domiati cheese made
from reconstituted ultrafiltrated whole milk and ripened in
brine solution at for 8 weeks

 

Hardness
Cohesiveness
Chewiness
Gumminess

Elasticity

Ripening Time (Weeks)

 

 

o 2 4 8
Means

3.85 4.07 4.40 5.63“

0.63 0.68 0.57 0.58

5.09 5.54 4.82 6.04“

2.21 2.30 _2.90 3.47

2.10 2.00 1.92 1.85

Standard
error

 

Sample with the same raw are significantly differ at *
p <0.05 and **, p< 0.01 from fresh ( 0 time ).
Values are means and standard errors of three replications.

225

Table 103. Components of whey of Domiati cheese made from
ultrafiltrated whole milk ripened in pouches and 8 % brine
solution for 8 weeks

 

 

 

 

 

Ripening’ Composition? (%)

time

(week)

Pouch 8% brine
Fat Protein Fat Protein

2 0.25' 3.70“ 0.13‘ 0.52“
4 0.36' 3.99' 0.15“ 0.79.
6 0.33' 4.00' 0.18' 0.88'
8 0.39' 4.19' 0.23' 1.16'

 

9Heans within columns for each components with the same
superscripts are not significantly different (p < 0.05) at
ripening time.

Values are the mean of duplicate analyses of three
replications.

Standard error for Fat, protein are 0.05, 0.49 for pouches
ripening and 0.03, 0.21 for 8 % brine ripening.

226

Table 10F . Calculated true loss of protein and fat from
Domiati cheese during ripening in pouches and brine solution

 

 

 

 

 

Ripening Weight (%)

time

(week) Pouch Brine

Protein Fat Protein Fat

2 1.12 0.10 2.10 0.25
4 1.59 0.12 2.37 0.45
6 1.70 0.16 3.10 0.69
8 2.00 0.25 3.48 0.89

 

Values are the mean of duplicate analyses of three
replications.

227

 

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000 06.6 66.0 66.6 00.0 06.0 00.6
00 06.0 66.0 00.0 06.0 00.0 06.6
00 00.0 06.0 06.6 6.0 0.6 00.6

 

c00000 000 000 0000 00 000000000 00000000 00 00000 000000000000.
000" 00000000 00000000 0x00000o0. wmu 000000 00000000 0x00000o0
000 00" 00000000 00000 H000x.

228

Table 118. Texture profile analysis of fresh and ripened UF-
and conventional Domiati cheese

 

 

 

 

Properties Conventional Ultrafiltration
Erssh usinfi_i§D
Hardness (N) 8.4tl.82 8.2il.3
Cohesiveness ( \A1) 0.710.23 0.31-0.03
Chewiness (N\Cn 13.136.14 3.610.15
Gumminess (N) 5.912.70 2.510.02
Elasticity (Cn) 2.310.12 1.410.2
Brittleness (N) 0.1 0.05
l_MQn§h Usans_1§D
Hardness (N) 15.110.75 12.310.6
Cohesiveness ( ‘00) 0.810.14 0.410.06
Chewiness (N\Cn 22.914.1 6.410.6
Gumminess (N) ll.5i6.9 4.9tO.5
Elasticity (Cn) 2.01o.o 1.2:o.o
Brittleness (N) 0.5 1.3:o.2
§_npn&hs Eggns_:§n
Hardness (N) 9.9:o.4 9.610.8
Cohesiveness ( \A1) 0. 7:0. 08 0. 6:0. 2
Chewiness (N\Cn 11.312.6 7.Stl.8
Gumminess (N) 6.8to.4 5.4:o.7
Elasticity (Cn) l.7tO.5 1.410.05
Brittleness (N) 2.3:o.o 1.5:o.2

 

Values are means and standard deviations of duplicate of three

replications.

N= force (Newtons) , A2\A1= areas of second\ first peak.

229

Table 11C. Color changes of fresh conventional and
ultrafiltrated Domiati cheese and ripened for three months in
pouches

 

 

 

 

 

Conventional Cheese Ultrafiltration Cheese
L a b L a b
Eresh

93.310.25 -3.3t.1 10.0iO.15 83.3:0.2 -3.8t0.2 12.6iO.2
1_H9n§h

91.210.3 -3.510.1 11.710.2 79.910.9 -3.1i0.2 13.4iO.4
2_H2n§h§

85.110.3 -1.5i0.2 13.510.3 74.4iO.1 -2.0i0.4 20.0iO.4

 

Values are the means and standard deviations of duplicate
analyses of three replications.

230

Appendix (12)

Table 12A. Yields and yield efficiencies of Domiati cheese
made from whey protein concentrate-supplemented whole milk

 

 

 

Added Yield Kg Kg Cheese Kg Cheese
protein per 100 kg per kg per kg
ratio supplemented total solids protein
mixture

1:0 17.50b 1.4' 5.0be
1:0.25 21.90“ 1.7' 5.8'
1:0.5 22.94' 1.7' 5.7'
1:0.75 24.80' 1.8b 5.4“”

1: 1 22.00' 1.5' 4.5°

 

I""”""""‘Means within column with the same superscripts are
not significantly different (p < 0.05).

Values are the mean of duplicate analyses of three
replications.

231

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232

Table 12C. Color changes of fresh Domiati cheese made from
whey protein concentrate-supplemented whole milk

 

Added Protein Ratio

 

 

 

Color
Control 1:0.25 1:0.5 1:0.75 1:1
L 96.75‘ 90.0b 84.83° 80.06d 74.00e
-2.2‘ -5.s° -6.2"° -7.5‘ -7.0"°
b 13.76 17.7c 18.5b 19.0” 20.0'
I,b,c,d

”Means within column with the same superscripts are not
significantly different (p < 0.05).

L - indicates lightness( 100 =perfect white)

a = + indicate redness; - indicate greenness: 0 = gray

b = + indicate yellowness: - indicate blue; 0 = gray

233

Table 120. Texture profile analysis Domiati cheese made from
whey protein concentrate-supplemented whole milk obtained
with Instron Universal Testing Machine.

 

 

 

Texture Added Protein Ratio
Profile
Analysis

Control 1:0.25 1:0.5 1:0.75 1:1
Hardness 18.05a 4.10b 3.20b 2.30b 1.27b
Cohesiveness 0.53' 0.40' 0.43' 0.48' 0.49'
Chewiness 18.03' 2.47b 2.06b 1.60b 1.00b
Gumminess 9.49' 1.36b 1.06b 0.90b 0.60b
Elasticity 1.90' 1.90“ 1.85' 1.45b 1.30c
Brittleness 1.00' 0.85' 0.80' 0.80' 0.70'

 

"b'c'dMeans within row with the same superscripts are not
significantly different (p < 0.05).

Values are the mean of duplicate analyses of three
replications.

234

Table 123. Components in whey from Domiati cheese made from
whey protein concentrate-supplemented whole milk

 

 

 

 

 

Drained Added Protein Ratio
Whey
Composition

Control 1:.25 1:.5 1:.75 1:1

‘ (%)

Total solids 6.77° 7.15° 8.10” 8.51b 9.45‘1
protein 1. 15' 2 . 03“l 2 . 43‘ 2 . 65" 3 . 30'
Ash 0.43” 0.85“ 1.07'b 1.81'b 1.91'

 

"b'c'd'fileans within row for each component with the same
superscripts are not significantly different (p < 0.05).
Values are the mean of duplicate analyses of three
replications.

LIST OE REFERENCES

Abd El-Salam, M.H., El-Shibiny, S.,El-Koussey, L.A. and
Haggag, R.F. 1983. Domiati cheese made with
ultrafiltreted reconstituted milk and lipolysed
recombined cream. J. Dairy Res. 50: 237.

Abd El-Salam, M.H., El-Shibiny, S., Moneib, A. F., Abo El-
Heiba, A. and El-Khamy, A. F. 1981. Addition of lipase
in the manufacture of pickled soft cheese from whole
and skim milk powder. Egyptian J. Dairy Sci. 9: 143.

Abd El-Salam, M.H. and El-Shibiny, S., Ahmed, N. S. and
Ismail, A.A. 1981. The use of ultrafiltration in
manufacture of Domiati cheese from Buffalo'milk.
Egyptian J. Dairy Sci. 9: 151.

Abd El-Salam, M.H., and El-Shibiny, S. 1982. Manufacture
of Domiati cheese from milk concentrated by membrane
ultrafiltration. II. Effect of rennet and starters.
Asian J. Dairy Res. 1: 187.

Abd El-Salam, M.H. and El-Shibiny, S. 1972. Changes in
proteins of Domiati cheese during pickling. J. Dairy
Res. 39:219.

Abou-Donia, S.A. 1986. Egyptian Domiati soft white pickled
cheese. New Zealand J. Dairy Sci. Technol. 21:167.

Abrahamsen, R.K. 1979. Cheesemaking from milk fortified
with ultrafiltrated whey protein concentrate.
Milchwissenschaft 34:65

Anis, S. 1984. Control of melting properties in process
cheese made from UF whole milk retentate. Paper
presented at Dairy Research Advisory Board meeting.
Utah State University. Logan.

Anonymous. 1980. Feta cheese production by ultrafiltration.
Am. Dairy Rev. 42:34A.

AOAC. 1984. "Official Method of Analysis". Association of
Official Analytical Chemists, Washington, DC.

Aschaffenburg, R. and Drewry, J. 1959. New procedure for

the routine determination of the various non-casein
proteins of milk. XV Int. Dairy Congr. III: 1631.

235

236

Barbano, D.M., Sciancalepore, V., and Rudan, M.A. 1988.
Characterization of milk proteins in ultrafiltration
permeate. J. Dairy Sci. 71:2655.

Barbano, D.M., and Bynum, 0.6. 1984. Whole milk reverse
osmosis retentates for cheddar cheese manufacture:
cheese composition and yield. J. Dairy Sci. 67:2839.

Besik, F., Zarnett, G., Pancuska, V., and Mlynarczyk, A.
1971. Reverse osmosis. Fd. Engineering 43 (7): 72.

Bourne, M.C. 1967. Deformation testing of foods. I. A.
Precise technique for performing the deformation test.
J. Food Sci. 32:601

Bourne, M.C. 1968. Texture profile of ripening pears. J.
Food Sci. 33:223.

Brandt, M.A., Skinner, E.z., and Coleman, J.A. 1963 Texture
profile method. J. Food Sci. 28: 404-409

Braselton, W.E., Meerdink, G.L., Stowe, 8.0., and Tonsager,
S.R. 1981. Experience with multielement analysis in
diagnostic clinical toxicology and nutrition. Amer.
Assn. Veterinary Diagnosticians. 14th Ann. Proceeding,
111-126.

Brown, R.J., and Ernstrom, C.A. 1982. Incorporation of
ultrafiltration concentrated whey solids into cheddar
cheese for increased yield. J. Dairy Sci. 65:2391.

Brown, C.G. 1986. Natural cheese from prefermented whole
milk retentate. Ph.D. Thesis Utah Stat University.

Logan.

Brown, R.J., and Ernstrom, C.A. 1982. Incorporation of
ultrafiltration concentrated whey solids into cheddar
cheese for increased yield. J. Dairy Sci. 65:2391

Brule, 6., Maubois, J.L., and Fauquant, J. 1974. Contents
of minerals elements in products from ultrafiltrated
milk. Le Lait 54:600.

Brule, G., and Fauquant, J. 1965. Mineral balance in skim-
milk and milk retentate: effect of physicochemical
characteristics of the aqueous phase. J. Dairy Res.
48:91.

Bundgaard, A.G., Olsen, O.J., and Madesen, R.F. 1972.
Ultrafiltration and hyperfiltration of skim milk for
production of various dairy products. Dairy Indst.
37:539.

237

Buruiana, L. M. El-Senaity, M.H. 1986. Volatile fatty acids
(VPA) in Teleme cheese during ripening. Egyptian J.
Dairy Sci. 14:201

Buruiana, L. M. and Farag, 8.1. 1983. The variation of amino
acids in Telema cheese during pickling. Egyptian J.
Dairy Sci. 11, 53.

Castigilioni, N. V. 1969. The recovery of proteins
contained in the whey. Indst. Aliment. Pinerolo 8:75.

Cheryan, M. 1986. Ultrafiltration handbook. Technomic
Publishing Co., Inc., Lancaster. '

Cohen, S.A., Bidlingmeyer, B.A., and Tarvin, T.L. 1986. PITC
derivatives in amino acid analysis. Nature. 20:769.

Cotton, S.G. 1980. Subject: Whey technology. The utilization
of permeates from the ultrafiltration of whey and skim
milk. J. Soci. Dairy Technol. 33:89.

Covacevich, H.R. and Kosikowski, F.V. 1977b. Skim milk
concentration for cheesemaking by alternative
ultrafiltration procedures. J. Food Sci. 42:1359.

Covacevich, H.R., and Kosikowski, F.V. 1974. Utilization of
ultrafiltration for cream cheese manufacture. J.Dairy
Sci.57:488.

.Covacevich, H.R., and Kosikowski, F.V. 1977a. Cottage
cheese by ultrafiltration. J. dairy Sci. 61:529.

Covacevich,H.R.,and Kosikowski, F.V. 1975. Mozzarella,
cottage, and cheddar cheese from ultrafiltered
retentates concentrated to maxima.J.Dairy Sci. 58:793.

Creamer,L.K, and Olson, N.F. 1982. Rheological evaluation
of maturing cheddar cheese. J. Food Sci. 47:631.

De Koning, P.J., de Boer, R., Both, P. and Nooy, P.F.C.
1981. Comparison of proteolysis in a low-fat semi-hard
type of cheese manufactured by standard and by
ultrafiltration techniques. Neth. Milk Dairy J. 35:35.

Deeth, H.C., Fitz-Gerald, C.M. and Snow ,A.J. (1983). A Gas
Chromatographic method for the quantitative
determination of free fatty acids in milk and milk
products. New Zealand J. Dairy Sci. and Technol. 18:
13.

Dubois, M.K.A., Gilles, J.K., Hamilton, P.A. and Smith, F.
1956. Calorimetric method for determinations of sugars
and related substances. Anal. Chem. 28:350.

238

El-Gendy, S. M. 1983. Fermented foods of Egypt and the
Middle East. J. of Food Protect. 46: 358.

El-Gendy, S.M., Abdel-Galil, R., Shahin, Y. and Hegazi, F.z.
1983. Use of salt-tolerant lactic acid bacteria for
manufacture of white pickled cheese (Domiati) ripened
without salted whey in sealed polyethylene pouches. J.
Food Protect. 46:335.

El-Sadek, G.M. and Motteleb, L.A. (1958). Effect of heat
treatment milk on the yield, quality and certain
properties of standardized separated milk cheese. J.‘
Dairy Res. 25: 85.

El-Shabarawy, S.A. 1985. Comparison of proteolysis in Edam
cheese manufactured by standard and by ultrafiltration
techniques. Egyptian J. Dairy Sci. 13:9

El-Shibiny, S., Abd EL-Salam, M.H., and Ahmed, N.S. 1973.
Effect of some additives on the yield, quality and
chemical composition of Domiati cheese. II . Whey
protein . Egyptian J. Dairy Sci. 1:56.

El-Shibiny, 8., El-Koussy, L.A., Gergis, E.A., and Mehanna,
N. 1983. The use of vegetables oils in making soft
cheese from ultrafiltered recombined milk. Egyptian J.
Dairy Sci. 11:215.

Ernstrom, C.A., Sutherland, B.J., and Jameson, G.W. 1980.
Cheese base for processing. A high yield product from
whole milk by ultrafiltration. J. Dairy Sci. 63:228.

Ernstrom, C.A., Sutherland, B.J., and Lameson, G.W. 1980.
Cheese base for processing: A high yield product from
whole milk by ultrafiltration. J. Dairy Sci. 63:228.

Ernstrom, C.A. and Anis, S.K. 1985. Properties of products
from ultrafilterd whole milk. Proc. International Dairy
Federation Seminar, New dairy products via new
technology , Atlanta, Ga.

Ernstrom, C.A and Wong, N.P. 1974. Milk clotting enzymes
and cheese chemistry. In: Fundamentals of Dairy
Chemistry, (Webb, G. R., Johnson, A. H. and Alford,
J.A., eds.). AVI Publishing Company, Inc. Westport, CT.

Feeley, R. M., P.E. Criner, E. W. Murphy, and E. W.
Toepfer.1972. Major mineral elements in dairy products,
J. Amer, Diet. Ass. 61:505.

239

Fenton-May, R.I., Bill Jr., C.G., Amundson, C.H., Lopez,
M.H., and Auclair, P.D. 1972. Concentration and
fractionation of skim milk by reverse osmosis and
ultrafiltration. J. Dairy Sci. 55:1561.

Fenton-May, R.I., Hill, C.G., and Amundson, C.M. 1971. Use
of ultrafiltration and reverse osmosis systems for the
concentration and fractionation of whey. J. Food Sci.
36: 14.

Fernandez, A., and Kosikowski, F.V. 1983. Low moisture
'mozzarella cheese from milks concentrated by
ultrafiltration and vacuum evaporation. J. Dairy Sci.
Suppl. 1, 66:86.

Fox, P. F., and Walley, B.F. 1971. Influence of sodium
chloride on the proteolysis of casein by rennet and by
pepsin. J. Dairy Res. 38, 165.

Fukushima, M., Sone, T., and Fukada, T. 1965. Effect of
moisture content on the viscoelastisity of cheese.
J. Soci. Mat Sci. Japan 14:270-273.

Garcia-Ortiz, R., Hardy, J., and Weber, F. 1980.
Physico-chemical aspects of the cold storage of
concentrates obtained by the ultrafiltration of raw
milk. Rev. Lait. Fr. 384:17.

Garnot, P., and Corre, C. 1980. Influence of milk protein
concentration on the gelling activity of chymosin and
bovine pepsin. J. Dairy Res. 47:103.

Gill, J.L. 1978. Design and analysis of experiments in
animal and medical sciences. Vol I. The Iowa State
University press. Ames, Iowa.

Glover, P.A. 1985. Ultrafiltration and reverse osmosis for
the dairy industry. Tch. Bull. 5. National Institute
for Research in Dairying. Reading, England.

Glover, F.A.,and Chapman, H.R. 1973. Milk concentration by
ultrafiltration for cheddar cheese manufacture.
Nordeuropaeisk Mejeri-Tidsskrift 39 (3):64. CF. Dairy
Sci. (Abst). 35:4350.

Glover, F.A., Skudder, P.J., Stothart, P.E., and Evans, E.W.
1978. Reviews of the progress of dairy science:
Reverse osmosis and ultrafiltration in dairying. J.
Dairy Res. 45:291.

Glover, F.A. 1971. Concentration of milk by ultrafiltration
and reverse osmosis. J. Dairy Res. 38:375.

240

Glover, P.A. and Brooker, B.E. 1974. The structure of the
deposit on the membrane during the concentration of
milk by reverse osmosis. J. Dairy Res. 41:89.

Green, M.L., Glover, F.A., Scurlock, E.M.W., Marshall, R.J.
and Hatfield, D.S. 1981. Effect of use of milk
concentrated by ultrafiltration on the manufacture and
ripening of Cheddar cheese. J. Dairy Res. 48:333.

Green, M.L., Scott, J., Anderson, M., Griffin, M.A.C., and
Glover, P.A. 1984. Chemical characterization of milk
concentrated by ultrafiltration. J. Dairy Sci. 51:267.

Green, M.L., Scott, R.J., Anderson, M., Griffin, M.C.A., and
Glover, P.A. 1984. Chemical characterization of milk
concentrated by ultrafiltration. J. Dairy Res. 51:267.

Gripon, J.C., Desmazeaud, M.J., Le Bars, D., and Bergere,
J.L. 1975. Etude du role des micro-organisms et des
enzymes au cours de la maturation des fromages. II -
Influence de la presseure commerciale. Le lait 55:502.

Hambraeus, L. 1982. Nutritional aspects of milk proteins.
In. P.E. Fox (ed), Development in dairy chemistry. Vol.
I. P 289. Elsevier Applied Sci. Publishers. London.

Harper, W.J. 1959. Chemistry of cheese flavors. J.Dairy
Sci. 42:207.

Harper, W.J. 1979. Factors affecting the application of
ultrafiltration membranes in the dairy food industry.
polymer Sci. Technol. 13:321.

Holmes, D. G., Duersch, J.W. and C. A. Ernstrom, C.A. 1977.
Distribution of milk clotting enzymes between curd and
whey and their survival during cheese making. J. Dairy
Sci. 60:862.

Horton, B.S. 1979. The present status of membrane
processing equipment. New Zealand J. Dairy Sci.
Technol. 14:93.

Ibrahim, M.K. 1963. Studies on the ripening of Domiati
cheese. Ph.D. thesis, Cornell University, Ithica, N.Y.,
USA.

Jarret, W. D., Aston, J. W. and Dulley, J. R. 1982. A simple
method for estimating free amino acids in cheddar
cheese. Australian J. Dairy Tchnol., 32, 55.

Jepsen, S. 1977. Ultrafiltration for danish blue cheese.
Dairy and ice cream field. 160 (4):78.

241

Kosikowski, F.V., Masters, A.R. 1983. Composition of wheys
from retentate-supplemented cheese milk and of cream
and skim milk from separated whole milk retentates. J.
Dairy Sci. 67:1887.

Kosikowski, F.V. 1986. Membrane separation in food
processing. In. McGregor, W.C. (ed), Membrane
separations in biotechnology. Marcel Dekker, Inc., NY.
P. 201.

Kosikowski, F.V. 1983. Age of UF retentate from farm fresh
milks and quality of cheddar and cottage cheeses. J.
Dairy Sci. Suppl. 1, 66:83.

Kosikowski, F.V. 1982a. Characteristics of cottage cheese
from water and permeate reconstituted retentates. J.
Dairy Sci. 65:1705.

Kosikowski, F.V. 1982b. Cottage cheese from highly heated
milks supplemented with ultrafiltrated skim milk
retentates . J. Dairy Sci. Suppl. 1, 65:73.

Kosikowski, F.V. 1979. Yields and volumes of cottage and
cheddar cheese as influenced by retentate additions. J.
Dairy Sci. Suppl. 1, 62:58.

Kosikowski, F.V. 1951. The liberation of free amino acids in
raw and pasteurized milk cheddar cheese during
ripening. J. Dairy Sci. 34:235.

Kosikowski, F.V. 1977. Cheese and fermented milk foods.
Edwards Bros., Inc. Ann Arbor, Michigan, USA.

Kosikowski, F.V. 1974. Cheesemaking by ultrafiltration. J.
Dairy Sci. 57:306.

Lawrence, R.C. and Gilles, J. 1982. Factors that determine
the pH of young cheddar cheese. N.z. J. Dairy Sci.
Technol. 17, 1.

Lawrence, R.C., Gilles, J., and Creamer, I.K. 1983. The
relationship between cheese texture and flavor. N.z. J.
Dairy Sci. Technol. 18: 175.

Ledford, R.A., O'Sullivan, A.C., and Math, K.R. 1966.
Residual casein fraction in ripened cheese determined
by polyacrylamide gel electrophoresis. J. Dairy Sci.
49:1098.

Lee, D.M., and Merson, R.L. 1974. Examination of cottage
cheese whey proteins by scanning electron microscopy:
Relationship to membrane fouling during
ultrafiltration. J. Dairy Sci. 58:1423.

242'

Lonsdale, H.K. 1982. The growth of membrane technology. J.
Membrane Sci., 10:81.

Mahmmoud, M. M. and Kosikowski, F. V. 1979. Quality and
yield characteristics of Domiati and Feta cheeses made
by ultrafiltration, ADSA annual meeting, 62:D 41,57.

Mahmmoud, M.M. 1980. Ph.D. Thesis, Cornell University,
Ithica, New York, USA.

Mann, E.J. 1982. Ultrafiltration of milk for cheesemaking.
Dairy Ind. Int. 47: 11.

Massaguer-Roig, S., and Kosikowski, F.V. 1983. Manufacture
of queso blanco (Minas Frescal cheese) with milk
partially concentrated by ultrafiltration. J. Dairy
Sci. Suppl., 1, 66:86.

Mathews,M.E., So, S.E., Amundson,C.H., and Hill, C.G.Jr.
1976a. Cottage cheese from ultrafiltered skim milk.
J. Food Sci. 41:619.

Matthews, M.E., Amundson, C.H., and Hill, C.G. 1976b.
Changes in distribution of nitrogenous fractions of
Cheddar cheese whey during ultrafiltration. J. Dairy
Sci. 59:1033.

Maubios, J.L. and Mocquot, G. 1971. Preparation of cheese
from a concentrate obtained by ultrafiltration of milk.
Le Lait 508:495.

Maubois, J.L. 1979. Recent developments of membrane
ultrafiltration in the dairy industry. In. Proceedings
of the Symposium on ultrafiltration membranes and
applications. Vol. 13, Plnum. New York, p. 305.

Maubois, J.L. and Mocquot, G. 1975. Application of membrane
ultrafiltration to preparation of various type of
cheese. J. Dairy Sci. 58: 1001.

Maubois, J.L. 1980. Ultrafiltration of whey. J. Soc. Dairy
Technol. 33:55.

Maubois, J.L., Mocquot, G., and Vassal, L. 1969. A method
for processing milk and dairy products. French patent
2,052,121.

Mavropoulou, I.P. and Kosikowski, F.V. 1972. Free amino
acids and soluble peptides of whey powders. J. Dairy
Sci. 56:1135.

243

Melachouris, N.(1969). Discontinuous gel electrophoresis of
whey proteins, casein and clotting enzymes. J.Dairy
Sci. 52:456.

Moreis, T.A. and Mckenzie, I.J. 1970. Feta cheese
manufacture from cow's milk. XV III Int. Dairy Cong.,
13 342.

Morr, C.V. 1984. Production and use of milk proteins in
food. Food Technol. 38:39.

Morr, C.V., Swenson, P.E., and Richter, R.L. 1973.
Functional characteristics of whey protein
concentrates. J.Food Sci. 38:324.

Morr, C.V. and Richter, R.L. 1988. Chemistry of processing.
In: Fundamentals of Dairy Chemistry, (Webb, G. H.,
Johnson, A. H. and Alford, J.A., eds.). AVI Publishing
Company, Inc. Westport, CT.

Nes, A. M. 1980. Manufacture of low-fat Gouda-type cheese
with addition of whey proteins to the cheese milk.
Meiriposten 69:35.

Nichols, D.J., and Cheryan, M. 1982. Dairy and vegetable
protein blends by co-extraction and co-filtration. J.
Food Sci. 47:486.

Nichols, D.J. and Cheryan, M. 1981. Production of soy
isolates by ultrafiltration: factors affecting yield
and composition. J. Food Sci. 46:367.

Noomen, A. 1977. A rapid method for the estimation of the
dissolved and the undissolved nitrogen compounds in
cheese. Neth. Milk Dairy J. 31:163.

Ocampo, J., and Ernstrom C.A. 1985. Cottage cheese from
ultrafiltrated skim milk. Paper presented at Dairy
Research Advisory Board meeting. Utah State University,

Logan.

Olson, N. F. 1975. Mechanized and continuous cheesemaking
processes for cheddar and other ripened cheese. J.
Dairy Sci. 58:1015.

Olson, N. F. 1977. Factors affecting cheese yields. Dairy
Indst. 42(4):14.

Omar, M.M. 1987. Microstructure and chemical changes in
Domiati cheese made from ultrafiltrated milk. Food
Chem. 183:196.

244

Ornstein, L. 1964. Disc electrophoresis. I. Background and
theory. Ann. New York Acad. Sci. 121:321.

Peri, C., Pomei, C., and Rossi, F. 1973. Process
optimization in skim milk protein recovery and
purification by ultrafiltration. J. Food Sci. 38:135.

Porter, M.C. and Michaels, A.S. 1971. Food applications for
membrane ultrafiltration. Food Prod. Develop. 5: 65.

Porter, M.C., and Michaels, A.S. 1970. Application of
membrane ultrafiltration to food processing. Proc.
Third International Congress of Food Science and
Technology., London.

Richter, M.L. 1983. Exploring ultrafiltration frontiers.
Dairy Field. 166:62.

Schormuller, J. 1968. Chemistry and biochemistry of cheese
ripening. Adv. Food Res. 16:231.

Setti, D. and Peri, C. 1976. Whey and skim-milk
ultrafiltration. 2. Parameters affecting permeation
rate in skim milk ultrafiltration. Milchwissenschaft
31:466.

Slack, A.W., Amundson, C.M., Hill, C.G.JR and Jorgensen,
N.A. 1982. On-farm ultrafiltration of milk: 1-
Technical feasibility studies. Process Bioche, 17:6.

Smits, P. and Van Brouwershaven, J. H. 1980. Heat-induced
association of fi-lactoglobulin and casein micelles. J.
Dairy Res. 47, 313.

Swaisgood, H.E. 1973. The caseins. Critical Rev. Food
Technol. 3: 375.

Thomas, T. D. and Pearce, K. N. 1981. Influence of salt on
lactose fermentation and proteolysis in cheddar cheese.
N.z. J. Dairy Sci. Technol. 16: 253.

Vakaleris, D.G., and Price, W.V. 1959. A rapid
spectrophotometric method for measuring cheese
ripening. J. Dairy Sci. 42:264.

Van Slyke, L., and W. Price. 1979. Cheese. Orange Judd Co.,
New York, NY.

Vieira, S. D. A., Goudedranche, H., Ducruet, P., and
Maubois, J.L. 1983. Elements de fabrication d'un
nouveau fromage bresilien de type minas Frescal par le
procede M.M.V. La Technique Laitiere. 978:4.

245

Von Reuter, H., D. Hisserich, and D. Prokopek. 1981. Study
on the formal kinetics of rennet coagulation of milk
concentrated by ultrafiltration. Milchwissenschaft,
36:13.

Walstra, P., and Jenness, R. 1984. Dairy chemistry and
physics. John Wiley and Sons. New York, NY.

Weeb, B.H., Johnson, A.H. and Alford, J.A. 1974.
Fundamentals of dairy chemistry, 2nd ed. AVI pub. Co.
Westport, CT.

Wesley, P. 1981. Automated UF systems yields 80 percent
whey protein. Food Dev. 15:38.

Whitney, R. McL., J. R. Brunner, K. E. Ebner, H. M. Farrell,
Jr., R. V. Josephson, C. V. Morr, and H.E. Swaisgood.
1976. Nomenclature of the proteins of cows'milk: Fourth
revision. J. Dairy Sci. 59:795.

Wingerd, W.H. 1971. Lactalbumin as food ingredient. J.
Dairy Sci. 54:1234.

Wong, N.P., LaCroix, D.E., And McDonough, P.E. 1978.
Minerals in whey and whey fractions. J. Dairy Sci.
61:1700.

Yan, S.H., Hill, C.G., And Amundson, C.H. 1979.
Ultrafiltration of whole milk. J. Dairy Sci. 62:23.

Zall, R.R. 1984. Membrane processing of milk on the dairy
farm. Food Technol. 38: 88.

Zall, R.R. 1983. Trends in whey fractionation and
utilization. A global perspective. Proc. Am. Dairy Sci.
Assoc. meetings. Madison, WI.

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