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THE FATTY ACED CGMPOSWON OF
FREE AND BOUND LiP‘lDS iN
FREEZEeQREED MEATS

T319535 for flu; Deqrw of M. S.
MECEIEGAN STM‘E {INNER-SET?
Erene Siam

198.4

 

 

 

TH 5515

“was--

LIBRARY "”

Michigan State
University

 

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ABSTRACT

THE FATTY ACID COMPOSITION OF
FREE AND BOUND LIPIDS IN
FREEZEFDRIED MEATS

by Irene Giam

The fatty acid composition of free and bound lipids in
freeze-dried pork, lamb, and beef was determined by gas-
liquid chromatography. The study was made on both raw
and cooked samples to establish, if any, the effect of
cooking on the fatty acid content, especially with reference
to the bound lipids fraction.

Sixteen acids were positively identified as being
present in pork, lamb, and beef. In the bound lipids
fraction, traces of saturated 013, 015, and 017 were
evident. Three peaks remained unidentified. These
unknown peaks are probably unsaturated acids, although
the possibility that they be oxidation products cannot
be entirely ruled out.

The bound lipids fraction of the meat samples studied
was found to be more polyunsaturated than the free lipids
fraction. The linoleic, behenic, and arachidonic acid
content of the bound lipids exceed that of the free

lipids fraction.

 

Irene Giam

Cooking did not appear to have any significant influ-
ence on the fatty acid composition.

The fatty acid composition of lamb and beef are
similar to each other but are quite different from that
of pork. The myristic and myristoleic acid content are
higher in lamb and beef than in pork. On the other hand,
the linoleic and arachidonic acid Content of pork exceed

that of lamb and beef.

THE FATTY ACID COMPOSITION OF
FREE AND BOUND LIPIDS IN

FREEZE-DRIED MEATS

by

Irene Giam

A THESIS

Submitted to the School of Advanced Graduate Studies of
Michigan State University in partial
fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Food Science

1964

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ACKNOWLEDGMENTS

I wish to express my very sincere appreciation and
thanks to Dr. L. R. Dugan, Jr. for his constant help and
guidance throughout the course of my studies here and
during the preparation of this thesis.

I am indebted to Dr. T. F. Irmiter, Associate
Professor of Foods and Nutrition, and Prof. L. J. Bratzler,
Professor of Food Science, for their critical reading of
this manuscript.

Acknowledgment is given to the Asia Foundation and
The Singapore Government for the scholarship which made
this study possible.

It is with the utmost gratitude that I dedicate
this thesis to my parents and members of my family for

their encouragement and support in my studies.

ii

TABLE OF CONTENTS

Page
ACKNOWLEDGMENT. . . . . . . . . . . . . . ii
LIST OF TABLES. . . . . . . . . . . . . . iv
LIST OF FIGURES O O O O O O O O O O O O 0 V
INTRODUCTION . . . . . . . . . . . . . . 1
REVIEW OF LITERATURE. . . . . . . . . 4
Preparation of Meat . . . . . . . 8
Moisture Analysis. . . . . . . . . . . 9
Lipid Extraction . . . . . . . . . . . 9
Total Lipids. . . . . . . . . . . 9
Free Lipids . . . . . . . . . . . ll
Bound Lipids. . . . . . . . . . ll
Fatty Acid Determinations . . . . . . . . ll
Isolation of Fatty Acids. . . . . . . ll
Preparation of Methyl Esters . . . . . 12
Gas Chromatographic Separation. . . . . 14
Identification of the Fatty Acids . . . 15
RESULTS AND DISCUSSION . . . . . . . . . . . 1?
Moisture Analysis. . . . . . . . . . 1?
Fatty Acid Distribution. . . . 17
Free Lipids versus Bound Lipids in Raw Meat . . 19
Free Lipids versus Bound Lipids in Cooked Meat . 26

The Fatty Acid Composition of Meat from
Different Animals . . . . . . . . . 27
SUMMARY AND CONCLUSION . . . . . . . . . . . 34
REFERENCES 0 o o o o o o o o o o o o o o 36

iii

IJST OF FIGURES
Figures

1. The fatty acid composition of free and
bound lipids Of freeze-dried raw pork

2. The fatty acid composition of free lipids
Of freeze-dried raw pork, lamb, and
beef . . . . . . . . . . . .

3. The fatty acid composition of bound lipids
of freeze-dried raw pork, lamb, and
beef .

A. The fatty acid composition of bound lipids
Of freeze—dried raw and cooked beef

5. Gas chromatographic separation of methyl
esters of free fatty acids isolated from
the bound lipids of freeze-dried raw pork

Page

D.)
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i A)
R)

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LU

Tables

I.

II.

III.

IV.

VI.

LIST OF TABLES

Fatty acid composition of lipid fractions
(% of total fatty acids) obtained from
freeze- dried raw pork. . .

Fatty acid composition of lipid fractions
(% of total fatty acids) obtained from
freeze-dried cooked pork. . . . .

Fatty acid composition of lipid fractions
(% of total fatty acids) obtained from
freeze- -dried raw lamb. . .

Fatty acid composition of lipid fractions
(% of total fatty acids) obtained from
freeze- dried cooked lamb. . . .

Fatty acid composition of lipid fractions
(% of total fatty acids) obtained from
freeze-dried raw beef. . . . . .

Fatty acid composition of lipid fractions

(% of total fatty acids) obtained from
freeze- dried cooked beef. . .

iv

Page

2O

21

22

23

24

INTRODUCTION

Among the dehydration methods applicable to foods,
freeze-drying is one of the more expedient methods for
the maintenance of the desirable functional and palata—
bility characteristics. The freeze-drying of meat has
the advantage of reduction of weight and long-term
storage stability. However, freeze-dried meat is still
subject to deterioration and this deterioration can be
quite excessive under adverse conditions or extended
storage. Deterioration in freeze-dried meat can be
conveniently divided into oxidative deterioration and
active carbonyl-amine browning. The former involves
oxidation of the lipid fraction in meat and this results
in rancidity.

The susceptibility of any natural fat to oxidative
rancidity depends upon its degree of unsaturation and
upon its antioxidant content. The fatty acid composition
is, then, one of the inherent characteristics of the fat
which has an effect on rancidity. Comparisons of ran-
cidity tests on extracted fat with those made on whole
tissue show that the lipid fraction primarily involved in
‘the rapid oxidative reaction which takes place in cooked
meats can be extracted with a mixture of chloroform and
methanol but not with neutral fat solvents (52). n

l

The great variety of fatty acids found in meat makes
the analysis Of fatty acid composition a major problem.
Accurate analysis of all fatty acids in a fat cannot be
expected from one method only. Combinations of methods
are required. However, gas-liquid chromatography provides
extraordinarily good resolution of components and is
consequently employed, but it cannot be considered the
ultimate answer to all analytical problems. Gas
chromatography is certainly one of the most valuable
analytical tools ever to become available to the fat and
oil field. This technique provides the most accurate,
most precise and most rapid means of estimating fatty
acid content yet devised. The method was introduced by
James and Martin (26) when they separated the normal
saturated carboxylic acids up to 12 carbon atoms in chain
length. Cropper and Heywood (9) extended the method to
the separation of the methyl esters of even-numbered fatty
acids up to behenic.

In general, the procedure involves the distribution
of the material, volatilized at the column temperature,
between a moving gas phase and a stationary liquid phase.
Different constituents move through the column at differ-
ent rates because of the difference in partition coeffi-
cients. Using a suitable detection system, the concen-
tration Of eluate in the effluent gas is plotted against
time. The esters are ordinarily employed for this separa-

tion because of their relatively lower boiling points.

The application of Parks techniques to the deter-
mination of fatty acid composition Of free and bound
lipids from freeze-dried meats of three species of
animals was made.

In this study, the lipid fraction extractable by
solvents such as petroleum ether, diethyl ether, or, chlor—
oform is considered ”free lipids." In mammalian tissues
the major portion of the lipids is present as lipoproteins.
Bonding by water molecules plays an important part in this
union between the lipids and the protein. Dehydrating
agents such as methanol, ethanol, and acetone, which
essentially rupture the lipid-protein linkage, may be
included in the solvent used for extraction. The lipid
fraction Obtained by this solvent mixture is regarded as

"bound lipids."

REVIEW OF LITERATURE

Oxidative Rancidity in Meat

 

Certain fats especially those of pork and poultry are
much more easily oxidized than other animal fats. Rancidity
in beef or lamb, by comparison, is not a pressing problem.
These specie differences are probably attributed largely to
the fatty acid composition. Chang and Watts (7), in agree-
ment with earlier studies, found that pork and poultry fats
were much more unsaturated than beef or lamb fats. Compari-
sons on rancidity tests on extracted fat versus whole tissue
shOwed the lipid fraction primarily involved in the rapid
oxidative reaction taking place in cooked meats can be
extracted with a mixture of chloroform and methanol but
not with neutral fat solvents. The 2—thiobarbituric acid
(TBA) tests performed on total lipids fractionated into
triglycerides and proteolipids demonstrated that the latter
are responsible for the intensive oxidative reaction induced
by heating muscle tissue. ”Tissue rancidity" results
because Of the highly unsaturated nature of bound lipids (52).t
Protein bound phospholipids are important food constituents
involved in the deteriorative reactions which take place
during processing and storage. It was found that phos-
pholipids from a particular tissue are appreciably more

unsaturated than triglyceride fats from the same source.

A

Their presence renders lipid more susceptible to oxidation,
which is a major factor in deteriorative reactions leading
to strongly flavored degradative products (28)..

Tappel (A5) found the oxidation of non-ether extrac-
tetfle lipids of freeze-dried beefappearedtx>account for
half of oxygen absorption. He noted that the oxidation of
ether soluble lipids play a minor role, accounting, at the
most, for 10% of total oxidative reaction. No studies
have been reported which relate the changes in ”free" and
"bound" lipids of freeze—dried meats to their fatty acid
composition, and which indicate whether freeze-drying

affects the proportion of free to bound lipids.

LipidfiExtraction,WIsOlation and Purification

In most cases, the extraction of lipids involves a
solvent system, such as ethanol-ether (A) or chloroform-
methanol (3, 15), to separate the lipids from the proteins
and other components of a tissue.

The contamination of lipid extracts with non—lipid
compounds has long been recognized as a problem (16). v
The procedure most commonly used for the removal of
these impurities is based on partitioning chloroform-
methanol solutions with water or salt (14, 15). Other
methods include dialysis (A2) , adsorption on cellulose
(29, A3), paper electrophoresis and chromatography (51),
chromatography on silicic—acid impregnated paper (2), and

sephadex (50).

Separation of Fatty Acids and Preparation
Of Methyl Esters

 

 

The routine application Of gas chromatography to
the determination of the fatty acid composition of a lipid
makes it essential to prepare methyl esters rapidly and
simply. Metcalfe and Schmitz (31) used an excess of
boron trifluoride-methanol reagent in their method of
esterification. Methylation of fatty acids was also
accomplished with 2, 2—dimethoxypropane (DMP) in methanol
and hydrochloric acid (33), with diazomethane (35),
methanolysis with a large excess of sodium or potassium
methoxide in absolute methanol (30), esterification with
dimethyl sulphate (53), or methanol hydrochloric acid
with microsublimation (AA), or with ethylene dichloride (8),
or methanol—hydrochloric acid on ion exchange resin (23).
The choice of the methylation procedure depends on the

nature and composition of the sample (A7).

Gas Chromatographic Separation

 

Since the original application of gas-liquid
chromatography by James and Martin (26), developments in
instrumentation and in techniques and diversified
applications have proceeded at a phenomenal pace. The
efficiency Of a gas-liquid partition chromatographic
column is influenced by many factors, such as the size of
solid support, density of packing, and the amount Of

liquid phase used (12). The discovery of new stationary

liquid phases permitted the complete separation of satur-
ated and unsaturated esters of the same chain length.
succinate polyester'of diethylene glycol is one of the
most effective stationary phases for separating fatty acid
esters because of the stability of the polyester at the
high column temperature required.

The practical identification of components in a
chromatogram is achieved by the use of standards. Members
in a homologous group may be identified by plotting the
logarithms of retention times, or retention volumes,
versus some group quality, such as chain length or degree
of unsaturation. "Carbon number" has been introduced for
presenting qualitative data from gas-liquid chromatography
of fatty acid esters (A9). James (25) has devised a
method to determine the degree of unsaturation of straight-
chain and simpler branched chain components by plotting
the logarithms of the retention time measured on one
stationary phase against similar values from a different

stationary phase.

EXPERIMENTAL METHODS AND PROCEDURE

Preparation of Meat

 

Commercial grade of pork (ham), lamb (leg), and beef
(inside top round) were Obtained from the Food Stores and
the Meats Laboratory, Michigan State University. Each
meat sample was cut into slices of approximately one-half
inch thick. The samples were trimmed free of all visible
fat. The meat was divided into two portions and treated
in one of two ways prior to freezing:

a. The raw meat was diced into pieces of about

I” x 3/A” x 1/2”.

b. The meat was dropped into boiling water and
cooked for 30 minutes at medium speed on an
electric range. Then it was cut into pieces
similar to those of the raw meat.

The diced meat samples were frozen as single layers between
aluminum foil on trays at —2OOF and then freeze-dried in

a Stokes freeze-drier (Model 2003F—2, lot P6569l, serial
P65753) for 20 hours. During the final 16 hours of
freeze-drying the "Heat Control” guage, controlling the
heating plate, was set at 150, which was equivalent to a
plate temperature of A2OC. The internal vacuum was

observed to fall to a minimum pressure of 70 microns.

After freeze-drying, the meat was ground with a
mortar and pestle and the finely divided tissue was

subjected to lipid extraction.

Moisture Analysis

 

Approximately 3-A g. of the ground meat were placed
in a 100 m1. beaker, which had previously been heated in
an oven, cooled in the dessicator and its weight determined
on an analytical balance. The beaker and its contents were
weighed accurately and then put in a drying oven at a
temperature of 10500 for A8 hours. After cooling for
30 minutes, the beaker was reweighed and the loss in

weight was considered to be due to water loss.

Lipid Extraction

Total Lipids

 

The extraction procedure was that Of Bligh and
Dyer (3), modified to include the ”wash” procedure of
Folch gt_§l. (15). A 10 g. sample of the ground meat was
homogenized in a Waring Blender for two minutes with
chloroform, methanol, and water. (Commercial reagent
grade of chloroform and methanol were used.) It was
imperative that the volumes of chloroform,methanol, and
water, at this step, be kept in the proportions of
l :2 :O.8. With this in mind, the amount of water actu-

ally added was adjusted to take into consideration the

water content of the meat sample. An equal volume of

lO

chloroform was then added and after blending for 30 seconds,
water was added and the blending was continued for a further
30 seconds. After' this dilution, the chloroform, methanol,
and water volumes must be in the proportions 2:2:1.8. Next,
the homogenate was filtered with slight suction through a
Whatman no. 1 filter paper on a Buchner funnel. Filtration
was normally quite rapid and when the residue became dry,
pressure was applied with the bottom Of a beaker to ensure
maximum recovery Of solvent.

The filtrate was transferred to a separatory funnel.
More chloroform and methanol were added and the whole
mixed well. This was the washing procedure of Folch et_gl.
(15). The final proportions of the ternary mixture of
chloroform, methanol, and water were kept at 8:A:3
(v/v/v), respectively. (Since chloroform was the more
volatile of the 3 components, about 5% excess chloroform
was added to compensate for losses during filtration so
that the critical proportions of the system were kept.)

The separatory funnel and its contents were allowed
to stand overnight in a cold room to facilitate the for-
mation Of a biphasic system. The chloroform layer con—
tained the purified lipids. This layer was drained into
a round bottom flask with ground glass joints. The solvent
was removed by evaporation under vacuum, using a Rinco
rotating evaporator. A warm water bath was used to facili—
tate the removal of chloroform, especially at the last

stages of evaporation under vacuum.

11

Free Lipids

 

Another 10 g. sample of the ground meat was extracted
with petroleum ether (b. p. 30-6000, analytical grade) in a
Soxhlet type of glass apparatus. A paper thimble with
porosity permitting rapid passage of the solvent was chosen.
The extraction period was about 8 hours at a condensation
rate of 1-2 drops per second. Heating of the solvent was
kept as low as possible. At completion of extraction,
the solvent was removed as before by evaporation under

vacuum on the Rinco rotating evaporator.

Bound Lipids

 

The meat sample from which the free lipids had been
entracted with petroleum ether was used for the bound
lipids extraction. In the extraction of bound lipids,
the method employed was that of the total lipids
extraction explained above. The lipid extract was taken
to dryness by evaporation of the solvent under vacuum in

a Rinco rotating evaporator.

Fatty Acid Determinations

 

Isolation of Fatty Acids

 

Dry lipid extracts were used for fatty acid deter-
minations. The lipid extracts were saponified with 25 ml.
of 0.5 N methanolic potassium hydroxide, per 200 mg. of

lipid material. The mixture was gently refluxed for 6 hours.

12

The contents of the flask were transferred to a separatory
funnel, 50 ml. of water were added, and the solution made
acid to phenolphthalein, by dropwise addition Of concen-
trated hydrochloric acid, and then 1 ml. excess acid was
added. The solution was extracted with 3 successive
25-ml. portions Of petroleum ether, and the combined

ether extracts were washed 3 times with 25-m1. portions of
distilled water, and then dried over anhydrous sodium

sulphate before being converted to methyl esters.

Preparation of Methyl Esters

Pretreatment of Resin.--Ten grams of Amberlite IRA-
AOO or CG-AOO (Rohm & Haas Co., Philadelphia, Pa.) were
stirred (magnetic stirrer) with 25 ml. of l N sodium
hydroxide for 5 minutes. The resin was allowed to
settle and the supernatant liquid was discarded. The resin
was successively washed with several portions of distilled
water to remove free alkali, then with three 25-ml. portions
of anhydrous ethyl alcohol1 to remove water, and finally
with three 25-m1. portions of petroleum ether to displace
the alcohol.

Preparation of Methyl Ester.--The dried petroleum
ether extract of the fatty acids was decanted onto the

alkali treated resin in a 250-ml. Erlenmeyer flask. Two

 

.r

lAnhydrous ethanol was prepared by refluxing ethanol
with magnesium ribbon, 5 g. per liter of alcohol. After
refluxing for A hours the alcohol was distilled.

l3

5-ml. portions of petroleum ether were used to wash the
residual solution into the flask. The solution, plus
resin, was stirred for 5 minutes. The resin, plus
adsorbed fatty acids, was allowed to settle and the

supernatant liquid discarded. The residue was then washed

 

free of fat by stirring with three successive 25-ml. por-
tions of petroleum ether and the washings were discarded.

A 25—ml. portion Of anhydrous methanol-hydrochloric

 

acid (5-6%, w/w) was added to the resin and the mixture 3
stirred for 25 minutes. The methanol solution was decanted E
through a rapid filter paper into a separatory funnel. The

resin was washed by stiring for 5 minutes with two succes-

sive fifteen—ml. portions of anhydrous methanol-hydrochloric

acid, again decanting each wash through the filter. Then

10 m1. of distilled water were added to the combined methanol

extracts and the solution was extracted with fifty ml.

of petroleum ether. The aqueous phase was drained into a

second separatory funnel and extracted twice with 20-ml.

portions of petroleum ether. The combined petroleum ether

extract was washed with 50-ml. portions of water until free

of acid (blue-violet with bromophenol blue), dried over

anhydrous sodium sulphate and then concentrated under a

gentle stream of dry nitrogen on a steam bath. An aliquot

of the fatty acid esters was used for the gas chromato-

graphic separation.

1A

Gas Chromatographic Spparation

 

Gas-liquid chromatography was carried out on a F & M1

(Model 500) programmed high temperature gas chromatographic
unit fitted with a Disc Chart Integrator (Model 201 B) and

2 The partitioning medium

a thermal conductivity detector.
was a polar ester (diethylene glycol succinate--LAC--3R--
728) in a ratio of 1 to 5, (w/w) on Chromosorb W (F & M,
60-80 mesh). The resolution of the methyl esters of the
fatty acids was observed to improve if the polar stationary
phase was treated with phosphoric acid. Consequently, the
Chromosorb W was mixed with a 1% solution of phosphoric
acid, and the mixture dried in an oven. The column

packing was prepared by slurrying the treated Chromo-

sorb with the required amount of a 20% solution Of the
polyester dissolved in chloroform. Additional chloroform
was necessary to form a uniform slurry. The mixture was
placed in a round bottom flask with ground glass joints

and the chloroform removed under vacuum in a Rinco rotat-
ing evaporator. The residual volatiles were removed by
heating the packing mixture, spread out in a porcelain dish,
in an air oven at about 110°C. A 6—foot coiled copper

column (1/A inch in outside diameter and 0.03 inch wall

 

1F & M SCIENTIFIC CORPORATION. Avondale, Pennsylvania.

2MINNEAP0LIS_HONEYWELL REG. CO., BROWN INSTRUMENTS
DIVISION, Philadelphia, Pa. Model No. 15307856-01—05—0—
000-790-07 009 Range -0.20 to +1.00 MV Rev. Inst. Ser.
No. 12191056183.

15

thickness) was packed with the polyester packing. The
column, with helium flowing through, was preconditioned by
heating for several hours at the operating temperature of
210°C. The helium flow rate was 75-85 ml. per minute,
as measured at room temperature by a soap bubble flow-
meter at the column exit.

The peak area was calculated from the pen trace
made by the Disc Chart Integrator. The fatty acid com-

position of each lipid fraction was calculated as area

 

per cent of the total fatty acids.
Identification of the Fatty Acids

The saturated acids (8, 10, 12, 13, 14, 15, 16, 17,
18, 20, and 22 carbon atoms), monounsaturated acids, (12,
1A, 16, 18, 21, and 2A carbon atoms), and polyunsaturated
acids (18:2, 18:3, and 20:A)l were identified by comparing
the sample chromatograms with a standard chromatogram Of
these known pure acids determined under the same isothermal
conditions Of 210°C or by programming the operating temper-
ature between lAO°C and 230°C at a constant rate of A°C
0r 7.9°C/minute.

The gas chromatograms had a number of unknown peaks;
an attemp was made to indentify these based on gas chromato-

graphic data. For a homologous series of straight chain

fatty acid methyl esters, the plot Of the logarithm of the

 

1The first figure denotes the number of carbon atoms,
the second figure, the number of double bonds.

l6

retention volume against the number of carbon atoms yields
a straight line for the saturated fatty acids; those with
one double bond fall along another line; and fatty acids
with more unsaturation fall along other lines. With the
polyester partitioning column used in this work, for a
given chain length, the acids emerged from the column in
the order of increasing unsaturation as exemplified by
the series stearic, oleic, linoleic, and linolenic. On
the basis of this information and a knowledge of the
retention times for the methyl esters of the pure known
acids, tentative assignments of chain length and degree

of unsaturation were postulated for these unknown peaks.

 

RESULTS AND DISCUSSION

Moisture Analysis

 

The moisture content of the freeze-dried samples
ranged from 3 to A% for the raw meat to 0.5 to 1.5%

for the cooked meat.

Fatty Acid Distribution

 

It was not possible to identify all the peaks. The
saturated acids (8, 10, 12, 14, 16, 18, and 22 carbon
atoms), monounsaturated acids (12, 1A, 16, 18, 21, and
2A carbon atoms), and polyunsaturated acids (18:2, 18:3,
and 20:A) were positively identified as being present
in raw and cooked pork, lamb, and beef. In the bound
lipids fraction of all samples traces of saturated C13,
015, and C17 were evident. Many workers have reported
the appearance of odd-numbered straight chain aciis and/0r
branched acids in sheep and 0x (18), butterfat (37, 38),
mutton and beef fats (l9), lamb caul fat (39), and bovine-
nm501e andliver (20). Capric and lauric acid were also
isolated from the back fat Of buttermilk—fed bacon pigs
(11) and mutton fat (17).

Three peaks remained unidentified (Figure 5). One
had a retention time after arachidonic and before nervonic,

while the other two unkowns were eluted after nervonic acid.

It was not fully established whether these unknown peaks

17

18

were those of oxidation products or acids. If they are
acids it is probably that these peaks represent unsatu-
rated rather than saturated acids.

The fatty acid composition of lipid fractions
extracted from raw and cooked pork, lamb, and beef are
given in Tables 1 to 6.1 Since the meat samples were
obtained from the University Food Stores and Meats
Laboratory, it was not possible to get exactly identical
samples, i.e., the cuts were approximately the inside
top round (beef), leg (lamb), and ham (pork), and each
sample was from a different animal, whose history and
diet were unknown. Consequently, we may expect variations
in the data since the composition of muscle tissue varies
with species, breed, strain, age, and sex Of the animal.
The composition may also be influenced by the type and
quantity of feed (10, 13, 21, 46).

There are differences in the data obtained from
different samples but, for most cases, they are small.
For purposes of comparison, the average value, which
represents all samples quite well, is used. There are no
other literature reports of a study on the fatty acid
composition of the freeze-dried meats (pork, lamb, and

beef) such as are considered here. Thus, it is difficult

 

1The data are the values from 3 different animals,
and the average is the mean of these values.

19

to compare values obtained in this study with those avail-
able in literature, for example, for aged lean beef and
pork (2A) or for the same meat tissues, but prepared

differently (7).

Free Lipids versus Bound Lipids in Raw Meat
The bound lipids of the meat from the three species !
of animals studied contained a greater amount of polyun-

saturated fatty acids than the free lipids fraction.

 

Unsaturated acids containing two or more double bonds 3
make up 15.8, 7.0, and 6.3% of the free lipids fraction and

about Al.1, 36.1, and 33.A% 0f the bound lipids fraction

in raw pork, lamb, and beef, respectively. These results

are in agreement with other studies (32) which indicate

that the neutral fat fractions are less unsaturated than

the phospholipids.

Each class of lipid (free lipids, bound lipids)
appears to have a characteristic fatty acid composition.
(Figure l). The myristic, palmitoleic, and oleic acid
content of pork, lamb, and beef are much higher in the
free lipids than in the bound lipids fraction. 0n the
other hand, the linoleic, behenic, and arachidonic acid
content of the bound lipids exceed those of the free
lipids. The major difference is the large amount of
arachidonic acid (11.5, 8.8, 9.0% in pork, lamb, and beef,
respectively) contributed by the bound lipids fraction

that has no counterpart (1.1, trace, trace, for raw pork,

20

00 + 0.00m

 

 

00 + 00000 .00 .00o00oo0 0000

00 + 0000: 00.0 0000 0000 - 000000 00000 000000000000 -- 0 .0 .0*

M0.0 0.0 0.0 .00 00000 .00 0.0 .00 M0.0 0.0 0.0 0.0 *0
0.0 0.0 0.0 .00 00000 .00 0.0 0.0 0.0 .00 .00 0.0 *0
000000 0.0 .00 .00 0.0 0.0 0.0 0.0 000000 0.0 .00 .00 0000
M0.0 0.0 0.0 0.0 0.0 0.0 0.0 .00 “0.0 0.0 0.0 0.0 *0
0.0 0.0 0.0 0.0 0.00 0.00 0.0 0.00 0.0 0.0 0.0 .00 0000
000000 0.0 .00 .00 0.0 0.0 0.0 0.0 000000 0.0 .00 .00 00
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0000
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0000
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0000
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0 0.00 0.00 0.00 0000
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 00
0.0 0.0 0.0 0.0 0 0.0 0.0 0.0 0.0 0.0 0.00 0.0 0.0 0000
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 00
000000 .00 .00 .00 0 0.0 0.0 0.0 0.0 000000 .00 .00 .00 0000
00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 00.0 0.0 0.0 0.0 00
00000 .00 .00 .00 0.0 0.0 0.0 0.0 000000 .00 .00 .00 0000
momhu .cHu. .cHP 3H». momhu. .hnv [Hus .ch momhp .cHu. 3H». [Hp NH
mompv {Hp [Hp CHO. wmomhp .cHu. .cHu. .90 @0605. 3.0.0 3H0. {HP OH

00000 .00 .00 .00 Am.o 0.0 0.0 .00 00000 .00 .00 0.00 w

A0m0p0>0v A00000>0v mfl0mm00>0v

000000 00000 000000 00000 000000 0000 0000

 

.xhoa 300 00000n000000 8000 00000000

000000 00000 000o0 0o 00 000000000 00000 00 00000000000 0000 00000--.0 00000

mH + Humam

 

 

 

 

 

. o o n
00 + H.00m m0 0 00000000 00mm
m0 + 00:0: Wm.0 C000 0000 I 000000 00000 00000000000: 1: 0 an a0*
00. 0 0.0 0.0 .00 00.0 0.0 0.0 0.0 00.0 0.0 0.0 .00 *0
00000 .00 .00 .00 Mm.0 .00 0.0 0.0 00000 0.0 .00 .00 *0
00000 .00 .00 .00 0.0 0.0 0.0 0.0 00000 .00 .0. .00 0H 0
00000 .00 .00 0. 0 Mm.0 0.0 0.0 0.0 00.0 0.0 0.0 0.0 *0
A0. 0 0.0 0.0 0. 0 0.00 0.0 0.00 0.00 00.0 0.0 0.0 .00 0000
M00000 .00 .00 .00 00.0 0.0 0.0 0.0 100000 .00 .00 .s0 00
00000 .00 0.0 .00 00.0 0.0 0.0 0.0 000000 0.0 .00 .00 0000
M0. 0 0.0 0.0 0.0 00.0 0.0 0.0 0.0 ”0.0 0.0 0.0 0.0 0H0
0. :0 0.00 0.00 .00 00.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0000
0 .00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 00.00 0.00 0.00 0.00 0000
0. 00 0.0 0.00 0.00 0.00 0.00 0.00 0.00 00.00 0.00 0.00 0.00 00
m. 0 0.0 0.0 0.0 0 0.0 0.0 0.0 0.0 00.0 0.0 0.0 0.00 0000
00. 00 0.00 0.00 0. :0 00.00 0.00 0.00 0.00 00.00 0.00 0.00 0.00 00
000000 .00 .00 .00 0 0.0 N 0.0 0.0 .00 000000 .00 .00 .00 0000
00. 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 00.0 0.0 0.0 0.0 00
M00000 .00 .00 .00 000.0 M 0.0 0.0 .00 00000 0.0 .00 .00 0000
@000». [Hus .00 .Hp 0.000.000 .00» [HP 300 $00.00 .00. 300+ .00 NH
M00000W .00 .00 00 A00000 .00 .00 .00 M00000 .00 .00 .00 00
00000 .00 .00 00 A©.© 0.0 0.0 .00 00000 .00 .00 0.00 m
A00000>0V A00000>0v mfl0m000>0v
000000 00000 000000 00000 000000 0000 0000
.3000 003000 00000 000000 E000 00:00 00.0
A00000 00000 00000 00 0V0 00000000 00000 00 00000000E00 0000 00000-1. 0 mqmdB

22

m0 + 0 00m

 

 

 

 

 

00 + 0u©0m .Q0 .0 ..00000000 00mm
m0 + 0:00..0 Rm.o 0000 0000 u 000000 00000 000000000000 In 0 .0 00*
000000 .00 0.0 .00 0.0 0.0 0.0 0.0 M0.0 0.0 .00 0.0 *0
00000 .00 0.0 .00 0.0 0.0 m.m 0.m 0.0 0.0 .00 0.0 *0
00000 .00 .00 .00 0.0 0.0 0.0 0.0 000000 .00 .00 .00 0000
00.0 0.0 0.0 0.0 0.m 0.0 0.0 0.0 00. 0 0.0 m.0 .00 *0
00.0 0.0 0.0 0 0 0.0 0.0 0.0 0.0 000000 .00 .00 .00 0 00
000000 0.0 .00 .00 00.0 0.0 0.0 0.0 000000 .00 .00 .00 mm
M0.0 0.0 0.0 .00 0.0 0.0 0.0 0.0 000000 0.0 0.0 .00 0000
0.0 0.0 0.0 0.0 0.0 0.0 0.0 m.m .0. 0 0.0 0.0 0.0 m000
m.0 020 mgw 0.0 0.00 m.mm mgflw 0.00 N0.m 000 0.0 0000 0000
0.0m 0.0m 0.0m m.0m Am.mm 0.00 0.00 0.00 00.0m 0.0m 0.0m 0.00 0000
0.00 0.00 0.00 m.00 00.00 0.00 0.00 0.0 Mm.00 0.00 0.00 0.00 00
0.0 0.0 0.0 m.m 0M0.m m.m 0.0 0.0 0.0 0.0 0.0 m.0 0000
0.00 0.00 0.00 0.00 0.00 0.00 0.m0 0.00 00.00N 0.00 0.00 0.00 00
0.0 0.0 0.0 0.0 0 0.0 0.0 .00 .00 00.0 0 m.0 0.0 0.0 0000
0.0 0.m m.m 0.0 0.0 0.0 0.0 0.0 00.0 0.0 0.0 m.0 00
000,00 .00 3‘00 .000 M 00000 0.0 {‘00 3‘00 M00000 .000 3.00 .c00 HHNH
000.00 .00 3‘00 N..O 000.00 3.00 .00 .000 000.000 .c00 m.O .000. NH
0090.0 .000. 3.00 300‘ 000.00 .c00. 3‘00 .000 000.00 .000 .00 .00 OH
00000 .00 .00 .00 M00000 .00 .00 .00 M00000 .00 .00 0.00 m
A00000>0V A00000>0v mA0w000>0v
000000 00000 000000 00000 000000 0000 0000

 

.0000 300 00000n0N0000 E000 00000000
000000 00000 00000 00 00 000000000 00000 00 00000000000 0000 0000--. m 00000

TABLE 4.——Fatty acid composition of lipid fractions (% of total fatty acids)

obtained from freeze—dried cooked lamb.

 

ipids

Total L

Bound Lipids

(average)

taverage)

I

\2

(average,

Free Lipids

Acid

 

A A
AMWMQJAAACDM
OJNONOF—O ()me 0001—1

0 'm o .
:T'HSNCIDFAONMS-«ONHWU hHH

i
)

trace
trace
trace
trace

OMF—UNONGNMMONCNQO 00H

iHCDKO—ZI‘MOCUOOCUHi-«OH

tr.
tr.

S—iS-q
+>p

HTM—IJ'MKOHONO ifKO HON

—:rH(MOCNONOCn$4QCUHiLOJH
H HNH pp p

tr.
tr.
tr.
tr.

\ONONHOONCDKO ONCUON H

MHNQOONMLOMOLHQ
H mm P p

tr.
tr.
tr.
tr.

UN xx

3

 

 

 

 

 

(l) (l) (D MMAAMAA OJAA
OOOONOUNF—HNHHF—ONCDOONgkON
(6mm 0 o o a o o
SagfidoHOUNmNUNl—(NNOONHLIHO
.p+ap rdOJN
.A/\./\‘/\/\./\_, W
NUNQNQOFimNNCIDOH QDCI)
HQQQOO—IgCUHUNKONHOONN SJHO
pup HNN
[\HUNCDINHOHNCIDCDNH [\-\O
FAQS—«OHOUNOICUOJCDNOOQDN hHO
.p+ap rdOJN
mathoonmoomlxooour Old)
spagrariorxowwxo<>awococdwlprio
p49+> H riNCU
WA A AA
(1) (1) Q) OJAAMAA ’\Q)/‘\Q) (Dz-\r'x
OOOOmQHdmwmwOoNooww
CUCUCUCU o o o ICU .LUCU o -
QEQLJHONCDONMMDOJr—i 905145-100
-p4J+)p H H“) -p +Jp
WVNHWV VW
O-U‘J‘HUN\O—:1'O(\l N
FAQS-«SAUNHOKDKHOKONHHOQL $454
pppp m Hm p pppp
ONMOx-JONCUOHN C3 mm
LES-{HS :f'r—iCDP-HCUP—MHLHFHLr—ir—i
+Lp+ap mCH p +ap
H :OOHmm UN[_\—-[\- LINK) ONCI)
S—IS—«F-‘S-a—II'NONOOCUUNOJO 51—100 $400
pupw HHN w
H r4 r4 HCUONH 3- r4
(IDONCU-Ir—KTKOKOOQCDCDCDHNO*-IT* *
HHHHHHHHHHHNNNCUCUQO

 

“14:1 + 15

trace - less than 0.5%

l

unidentified peaks

b, c

*a’

2See footnote, p. 18.

l + 13

312

24

 

 

ma + Humfim

 

 

 

 

 

NH + HumHm .wH .Q soponOOH comm
ma + Huaaa sm.o coco coca - ooosoH oxooo ooaoaosooacs -- o .o “as
s.o s.o m.H .sp H.H .ap s.H a.a Ao.H W .ao .so s.m *o
m.o .so m.H m.o o.m m.m s.m m.m Am.o .so s.o m.H so
Aoomgp .Lp .hp .su m.o o.H 0.0 .pp “momspw .pp .hp .9p anm
m.o .so m.H 0.0 0.: m.m m.m m.m Ao.H .ao m.o m.m so
m.H s.H s.H :. m 0.0 m.oH o.s w.m AooosoM .so m.o .sp auom
“comps .so m.o .ao Am.m m.m H.H m.m “compo .so .so .so mm
“momsp .hp .9» .pp A©.o .pp w.o m.o Amompp .pp .pu .hp HuHm
m.m m.H m.m .m Am.m w.m m.m a.m Am.H m.H m.m m.H mnwfi
H.w m.m m.m o.mH H. Hmw m.mm m.am m.mfi M3,; m.a m.a m.a mama
H.3m 0.3m H.mm m.:m m. mm m.mm a.mm m.mm o.am m.mm m.mm q.mm Huma
m.sfi m.mH m.mH o.ma m.oH a.oH m.oH H.0H m.mfi :.sfi m.am m.mH ma
No.s w.m H.s o.m m m.: m.m m.m m.m :.m d.mH m.m m.m Humfi
Mo.om 0.0m s.mfi m.mH m.aH w.:H ©.:H m.aH m.om 0.0m s.mH m.om ma
s.H m.H o.m H.H a m.o H.H v.0 s.o Ao.m m.m m.m H.H Huafl
Am.m 0.: @.m m.m o.H m.H o.H s.o Am.: m.m m.a m.: aH
oooso .sp .so m.o Am.o o.H s.o .ao compo .so .so .ao Humfl
oomhp .pp .9» .pp oompp .pp .9p .9p oompu .9p .9p .hp NH
wompp .9p .9p .9p mowhp .pp .hp .pu compo .pp . p .pp OH
momhp .sp .pp .pp oompp .9p .9p .Lp oompp .pp .pp H.9p m
Hommsm>wv Aommpo>mv mAmmmso>mV

moaoaq Hoooe moaoaq ossom moaoaq oosm oaoa

 

 

Amoaoo spams Hoooo so a

.moop 3mg UoHsUImNoopm Song UoQHmppo
V msoaoooao oaoafi so doapamoosoo oaoo spasm--.m mamas

mH + Hanm

 

 

 

NH + HumHm .wH .Q .mp02poom comm
mH + HHHHHlH sm.o coco mmoH - oooaoH oxooo ooHHHocooHss -- o .p “as
Amomhp .Hp .hp .hp Amowpp .Hp .pu .Lu Aw.o .Lp H.H ©.o *o
Mooosp .so .so m.o Hm.H m.m m.H ©.H Hm.o .ao s.H m.o so
moms» .hp .pp .Hp Amompp .hp .hp .pp Aoompp .9p .9p .9p Huzm
m.o m.o H.H HH.m m.m :.m m.H Ho.H .so m.H m.H so
Wm. H m.m o.H H.H H.m H.m s.m H.H As.o m.o m.o m.o :"om
m. o 0.0 .sa s.o s.H :.m m.H H.H Hoooso .so m.o .sp mm
Ms. 0 m.o m.o o.H Hooosp m.o .so .so Hoooso .so .so .ao HnHm
m. m m.H H.m s.m Am.m m.m H.H a.m Am.m s.H w.m m.m man
m.m H.H w.m H.m m.sH m.mH s.HH a.mH m.m m.a m.: m.m m.mH
:.mm m.mm s.mm m.mm 0.0m o.©m m.mm m.mm o.mm m.mm m.mm s.om H. wH
m.mH o.mH m.mH m.mH m.oH m.m o.m m.mH 0.0m m.sH o.Hm m.mm mH
w.m 0.0 ©.w o.w m m.m H.H m.m H.s .m. o.HH a.s a.oH H. .oH
m.Hm m.om m.mm w.om Am.sH m.mH m.sH m.wH Ho.mH o.om H.0H H.sH mH
w.H H.m o.m H.H aMm.o 0.0 o.H w.o o.m H.m m.H H.m HnaH
:.m m.: o.m m.m m.H o.H o.H s.H m.: m.: :.m 3.: :H
Hoodoo .ao .so .so As.o v.0 .so H.H Moooso .so .ao .s» Han
womcHu. .vHu .cHu .cHu. mmomcHus [Hus .ch .hp momhp .ch .pHp .ch NH
momch .ch .cHu .cHus momch .aHus .Hp .99 momhp .ch .ch .ch OH
momhp .9p .9p .pp Mmomhp .pp .hu .pp “oompp .Lp .Hu H.Hp w
Ammmpm>mv Aommpo>mv mflmwmpm>mv

moHoHH Hoooe moHoHH ossom moHoHH oosm oHo<

 

.mmon ooxooo ooHnonmNmopH EOHH cochppo

HmoHoo soomH Hopos Ho av acoHooosH oHdHH Ho soHonoosoo oHoo spasm--.m mque

26

lamb, and beef, respectively) in the free lipids fraction
(Tables 1, 3, and 5). A similar trend was found for
linoleic acid, with the bound lipids fraction contributing
29.5, 24.6, 21.1% as compared to 12.1, 5.1, 4.4% from the
free lipids fraction of raw pork, lamb, and beef, respec-
tively. These results are consistent with the observation
of Kuchmak and Dugan (27). The same trend was found in

aged lean beef and pork (24).

 

Free Lipids versus Bound Lipids in Cooked Meat

 

Polyunsaturated fatty acids make up 15.6, 9.6, and
8.2% of the free lipids fraction and about 42.3, 34.8, and
26.9% of the bound lipids fraction (in cooked pork, lamb,
and beef, respectively). Arachidonic acid (12.3, 7.0, and
6.1% in cooked pork, lamb, and beef, respectively) in
bound lipids fractions significantly exceeds the amount
present in the free lipids fractions (0.7% for each of the
meat samples) in the cooked samples. Linoleic acid was
more abundant in the bound lipids fraction (29.0, 25.1,
and 17.5%) than in the free lipids fractions (12.8,

6.3, and 5.2% in pork, lamb, and beef, respectively) in
the cooked samples.

There does not seem to be much difference in the fatty
acid content of raw and cooked meat, either in the free
lipids or bound lipids fraction, which may tend to indicate
the liberation of more tightly bound lipids on cooking.

Only in beef is the oleic acid content of the cooked sample

27
greater than that of the raw meat. However, this difference
may be attributed to the variations in data rather than to
the effect of cooking.

In a study of the fatty acid content of meat and
poultry before and after cooking, Chang and Watts (7) also
concluded that the differences which they observed were
not due to cooking.

The Fatty Acid Composition of Meat
from Different Animals

 

Prominent differences appear in the myristic, myris-
toleic, linoleic and arachidonic acid content of the free
lipids fraction (Figure 2). The amounts of myristic and
myristoleic acid are higher in lamb and beef than in pork.
On the other hand, the linoleic and arachidonic acid content
of pork exceed those of lamb and beef. In their studies
on meat and poultry, Chang and Watts (7) observed the
fatty acid distribution varied greatly from species to
species. They found the linoleic acid content of beef and
lamb was less than that of pork, which in turn was less
than that of turkey and chicken. This trend was also
evident in this study where linoleic acid of pork accounts
for 29.5% of the bound lipids fraction as compared to
24.6% and 21.1% for the bound lipids of lamb and beef,
respectively (Figure 3). Also, Ostrander and Dugan (32)
observed that the linoleic acid of pork depot far was much

higher than that of beef and lamb.

28

The fatty acid composition of beef and lamb are
similar to each other but are quite different from that
of pork. This is to be expected as the cow and the lamb
are ruminant animals. Since the early work of Burr and
Burr (5, 6), it has been recognized that animals are
unable to synthesize fatty acids containing more than
one double bond if none is supplied in their diet, although
they apparently have the ability to utilize dietary foods

containing di- or tri-unsaturated fatty acids to synthesize

 

more highly unsaturated ones (48). Diets rich in unsat-
urated oils modify depot fats of most animals to resemble
dietary fat, but ruminant depot fats are relatively
unaffected (22, 36, 40). This probably due to the hydro-
genation of dietary unsaturated fatty acids by rumen
microflora (34, 40, 41), giving rise to less unsaturated

acids.

.xsom 3mg cmHnouonmnm mo mcHQHH 0:509 vcm mopm Ho coHpHmoQEoo UHom prmm oLBII.H .mHm
oHoa spasm

 

 

 

 

 

 

o D Huzm m :"om mm HHHN man mumH HuwH wH HumH 0H HnsH :H HHNH NH OH ,
, p RVMJHV

pH; H-gd-Ho‘JQ _—HH ——g p u o

 

 

 

 

29

:H

H&.o

Cusp mmoHv oompp n

p
monk E

 

 

 

 

HHom

chom

 

 

 

(spice Kiieg {eioi JO %) uotitsodmoo ptoe Kiieg

.3906 Soy ploonmNmmhm mo mUHmHH @2309 cam copy mo coHpHmOQEoo UHom Hupmm oQBII.H .me

oHo< spasm

 

 

on
ace

29

:

A&.o

Cmcp mmmHv woman u
mosh

pcsom

  

Ha!

H
.

 

HuHN m :"ON mm HHHN muwH man HuwH wH HumH mH
p

 

 

 

 

 

 

 

H

":H

p

 

aH HumH H OH .
p o p Lflp. o

 

 

(sptoe Ride; Ieioi JO %) uotitsodmoo ptoe Kiieg

.Hmop new .QEmH .xsog 3mg omeoumNoohH mo mUHQHH owpw Ho COHpHmogEoo oHow hpumm mfleun.m .me
cHoo spasm

Huzm o snow mm HHHN muwH muwH Han mH Han

 

Izofl Em. oopzqufl on: 3 “—

Ham.o

O
3ocmcu wmoHv momsp n H

god .0

nEoH mg
.83 I

7”,!)

"////”////””//””//””/l””l”””llA

 

 

””IIII””””””’”I

W”””.”l§

0H

Inn/”Illunnllnn

'

H

a:

1?

3H

H

HNH

NH OH w

 

mfg

pap

“up pop poo

L

.0
.w

TOH

 

(spree K412; Ieio; JO g) uotixsodwoo ptoe Kiieg

 

 

. mm cm . .
m D c QEwH xsom 3mg omHhcamNmon mo mcHQHH cadon mo COHuHmOQEoo UHom Hpumm m:B::.m .me
oHoo spoon

 

 

   
 
 

 

 

o - Q Hmzm w :nom NN HHHN muwH NuwH Hum " u u
1.7 a J u m w.— z. M _ . H HMH Han an HamH ainH HENH “MM omw pmgo
v , , n n , u
r ” I , w I
, . I is
I
I l . l
I l l I :
0 n n , .
, n , n a
” r ” 11OH
Us ” , ” .wNH
, w
n a
Ham.o 7
Camp mmoHV momhp u p .imH
xsoma m Mama
QEQH: w tam
a... “a
_ .

(spree Edie; 1930; 30 %I) uotitsodwoo ptoe Kiieg

.Hmwp Umxooo cum 3mg UmHHUIonon mo mUHQHH 0:309 Ho COHpHmOQEoo UHom prmm o:E::.: .me

O

oHow spasm

o Huam o snow mm HnHm mumH mumH HuwH mH HumH

 

our as

32

Hem.o cop
mmmHV oomsp I p

@3600 D

sop..-

 

as:

 

mH

HUSH :H HHNH

NH

OH

O

 

 

 

 

 

Hin-

so

pp

pp

irOH
iuNH
11:H
0H
wH
LJON

Hmm

 

de
om
mm

(sptoe K3193 Ieioi JO %) uotqtsodwoo ptoe Kiieg

.meom oonHpcmchs udommpgop .o .9 qm .xpom 3mg UoHscnmempm mo moHQHH canon m£p
Eopm cmpmHomH mOHom mppmm omsg mo mpmpmo Hmcme mo coHmeonm 0H£QmsmoumEop£o mmO|u.m .mHm
AmopscHEv mEHB

 

 

 

 

 

 

 

mm ON mH NH 3 OH w w 3 N O
1') (1 (fill i < l .
o o. HZHHN w u ”
mmHHmme J mam..-
JHON _L i-
%
HuwH
wH i.
A
a 1,!
u
3 is
34
it

 

 

Nan mH

esuodsag aepaooeg

SUMMARY AND CONCLUSION

The fatty acid composition of free and bound lipids
in freeze-dried pork, lamb, and beef (raw and cooked) was
determined by gas-liquid chromatorgraphy. The saturated
acids (8, 10, 12, 14, l6, l8, and 22 carbon atoms),
monounsaturated acids (l2, l4, l6, and 18, 21, and 24
carbon atoms), and polyunsaturated acids (18:2, 18:3, and
20:4) were positively identified as being present in raw
and cooked pork, lamb, and beef. In all the bound lipids
fraction, traces of saturated C13, C15, and C17 were evi-
dent. Three peaks remained unidentified. It was not
fully established whether these unknown peaks were those
of oxidation products or fatty acids. However, if they
are acids it is probably that they are unsaturated rather
than saturated acids.

In each case, the bound lipids of the meat from the
three species of animals studied contained a greater
amount of polyunsaturated fatty acids than the free
lipids fraction. Each class of lipids appears to have a
characteristic fatty acid composition. The myristic,
palmitoleic and oleic acid content are much higher in the
free lipids than in the bound lipids fraction. 0n the
other hand, the linoleic, behenic, and arachidonic acid
composition of the bound lipids exceed those of the

free lipids.

34

35

There does not seem to be any major quantitative dif-
ference in the fatty acid content of the raw and cooked
meat, either in the free lipids or bound lipids fraction,
which may tend to indicate the liberation of more tightly
bound lipids by cooking. Only in beef is the oleic acid
content of the cooked samples greater than that of the
raw meat. However this difference may be attributed to
the variations in data rather than to the effect of cooking.

In both raw and cooked meat, prominent differences
appear in the myristic, myristoleic, linoleic and arachi—
donic acid content of the free lipids fraction of the
different meat samples. The amounts of myristic and
myristoleic acid are higher in lamb and beef than in pork.
But, the linoleic and arachidonic acid content of pork
exceed those of lamb and beef. These data tend to support
and identify the greater susceptibility of pork to

oxidation than that encountered in lamb and beef.

10.

11.

REFERENCES

ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. 1960.
Methods of analysis, 9th ed., Association of
Official Agricultural Chemists, Washington D. C.

BIEZENSKI,, J. J. 1962. A simple chromatographic
technique for removal of non-lipid contaminants
from lipid extracts. J. Lipid Res. 3, 120.

BLIGH, E. G., and W. J. DYER. 1959. A rapid method
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