E F F E C T OF HARVESTING CONDITIONS ON MOLD COUNT
OF BLACK RASPBERRIES

By
KUCHIBIIATLA LAKSHMI NARASIMIiAM

A THESIS
S u b m itted to the S ch o o l of Graduate S tu d ies of M ichigan
State C o lle g e of A g r ic u ltu r e and A pplied S c ie n c e
in p a r tia l fu lfillm e n t of the req u ir e m en ts
fo r the d e g ree of

DOCTOR OF PHILOSOPHY

D ep artm en t of F ood T echnology

1953

ACKNO WLEDGMEN TS

The author is

d eep ly indebted to D r. C. L . B ed ford fo r h is

e n c o u ra g em en t, g u id a n ce, and n e v e r -fa ilin g

help throughout the in v e s ­

tigatio n .
G ratitude is

e x p r e s s e d to P r o f e s s o r W. F . R ob ertson , of the

H orticu ltu re D ep a rtm en t, fo r su g g e stin g the r e s e a r c h p ro b lem , g u i­
d an ce, h elp , and c o u r te s y , w ithout w hich the ta sk would have s e e m e d
h a rd er.
The author w is h e s to e x p r e s s his

s in c e r e ap p recia tio n to D r.

E. S. B en ek e, B otany and P la n t P a th o logy D ep a rtm en t, fo r the r e a d i­
n e s s with w hich he gave u n stin tin g ly of h is te c h n ic a l know ledge and tim e .
Thanks a r e exten d ed to the m anagem ents of B u rn ette F a r m s
P ack in g Com pany, K e e le r , M ichigan, and L a w ren ce P ack in g Com pany
and L a w ren ce F r o z e n F o o d s, L a w re n c e, M ich igan , fo r providing n e c ­
e s s a r y help to c a r r y out the e x p e r im e n ts .
G ratefu l aclu iow led gm en ts a re a lso due to D r. S ala h E. M.
L outfi fo r valu ab le

s u g g e s tio n s , and to M iss K athleen C ase fo r g e n ­

e r o u s ly typing the p r e lim in a r y d ra fts of the m a n u scrip t.

TABLE OF CONTENTS

P age
IN T R O D U C T IO N ................................................................................................................

1

LITERATURE CITED

3

F a c to r s

..................................................................................................

that In flu en ce the Mold Count in B e r r ie s

...............

4

.........................................................................................................

5

H um idity r e q u ir e m en ts fo r m o l d s ....................................................

5

M atu rity of

7

T em p eratu re

.e r r i e s

and its e ffe c t on m old count

E ffe c t of h a r v e s t on m old count
Holding of b e r r ie s

. . . .

.....................................

8

and its e f fe c t on m old c o u n t ...............

9

W ashing and s o r t i n g ......................................................................................

10

M old Counting

.............................................................................................................

11

Standards fo r the N um ber of M olds A llow ed in
F ood P ro d u cts .............................................................................................................

13

A p p lication of Howard M ethod to B e r r ie s

......................................

14

........................................................................

16

..................................................................................................

16

1.
E ffe c t of the sta g e of m a tu rity upon the m old
count in black r a s p b e r r ie s
....................................................................

16

2.
E ffe c t of h a r v e stin g b lack r a s p b e r r ie s a fte r
r a i n f a l l ........................................................................................................................

17

EXPERIM ENTAL PROCEDURE
E x p e rim en ta l P la n

ii i

P age
3.

E ffe c t of shaking the b a sh e s

4.

E ffec t of holding black r a s p b e r r i e s ..................................

5.

E ffect of d iffe r e n t m ethods of w ashing

....................................................

.........................

17
18
18

6A.
C om p arison of o ffic ia l m old count m ethod
w ith the in e d ifie d m ethod....................................................................................

19

E ffect of dilution on m old c o u n t ...................................................

19

6B.

M ethods of P r o c e d u r e ..........................................................................................

27

Thawing cf

- e r r i e s ..........................................................................................

27

Pulping of

la c

. .............................................

27

M ethod fo r m old counting

.........................................................

27

P r e p a r a tio n o f p e c tin so lu tio n

........................................................

28.

r a sp b e r r y sa m p le s

D ilution m ethod fo r e stim a tin g m old count in
.............................................................................................................
the b e r r ie s
RESULTS

29

......................................................................................................................................

30

E ffect

of Stage of M aturity of B e r r ie s on Mold Count . .

30

E ffect

of H a rv estin g A fte r Rain at D iffe r e n t In te r v a ls . .

34

H ourly i n t e r v a l s ..................................................................................................

34

Day i n t e r v a l s .......................................................................................... ...

37

E ffe c t of V a r ie ty on the M old C o u n t s ...........................................................
E ffect on the M old Count in B e r r ie s of Shaking the
B u sh es B e fo r e H a r v e s t i n g ...............................................................................

iv

40

40

Page

E ffe c t on the Mold Count of Holding D ry and Wet
B lack R a sp b e r r ie s A fter H a r v e s t i n g ....................................................

44

E ffe ct of W ashing T reatm en t on the Mold Count
in B e r r i e s ........................................................................................................................

49

E ffe ct of D ilu tion s on Mold Count of B lack R asp b erry
P u l p .......................................................................................................................................

56

C o m p a riso n of o ffic ia l m ethod w ith m o d ified
technique fo r m ea su r in g m old count in black
r a s p b e r r i e s ............................................. ..............................................................

C6

E ffe c t of adding d ifferen t am ounts of p ectin
so lu tio n to b la ck r a sp b e r r y pulp on m old c o u n t ...............

60

D IS C U S S IO N ...........................................................................................................................

64

SUMMARY AND CONCLUSIONS

.......................................................................

70

B IB L IO G R A P H Y ................................................................................................................

72

A PPEN D IX

75

...........................................................................................................................

v

LIST OF TABLES

TABLE
I.
II.

III.

IV.

V.

VI.

VII.

VIII.

IX.

Pasre
o
E x p erim en ta l P la n

....................................................................................

20

O fficia l W eather Data fo r July, 1951, in
P a w P aw , M ichigan
...............................................................................

24

A v era g e M eld Count of B e r r ie s at D ifferen t
S ta g es of M atu rity, C o lle c ted at D iffe re n t
In te r v a ls A fter R ain, D uring the 1952 S e a so n

. . . .

31

A v e ra g e M old Count of B e r r ie s C o lle c te d
at D iffere n t S ta g e s of M aturity, and A n a ly sis
of V arian : e .....................................................................................................

32

A n a ly sis of V a rian ce of the M old Count in
B e r r ie s C o lle c te d at D iffe re n t In te rv a ls
A fte r R a i n .........................................................................................................

35

A v era g e M old of Logan and C um berland
B lack R a sp b e r r ie s in D iffe re n t S ta g e s of
M aturity B e fo r e and A fter Shaking the
B u sh es f o r H a r v e st
...............................................................................

41

R eduction in M old Count of L ogan and
C um berland B lack R a sp b e r r ie s of D iffe re n t
S ta g es o f M aturity A fter Shaking the B u s h e s ...............

44

M old Count of D ry and W et B la c k R a sp b e r r ie s
F r o z e n Im m e d ia te ly A fte r H a r v e st, and F r o sen
A fte r H olding f o r S ix and T w elve H ours at 76°
to 711° F ................................................................................................................

46

E ffe c t of W ashing on M old Count of B lack
R a s p b e r r i e s .....................................

51

vi

TABHE
X.

XI.

XII.

XIII.

XIV.

XV.

XVI.

XVII.

XVIII.

XIX.

P age
A n a ly sis of V a ria n ce of M old Counts
E stim a te d by O ffic ia l M ethod and M odified
Technique fo r M easuring M old in B lack
R a s p b e r r i e s .....................................................................................................

r9

E ffe ct of Adding D ifferen t A m ounts of
P e c tin S olu tio n to B la c k R a sp b e r r y Pulp
on Mold C o u n t .............................................................................................

6l

Mold Count on F r u it H a r v e ste d at D iffe r e n t
H ourly In te r v a ls A fte r R ains (1952 S e a s o n ) ......................

76

E ffe c t of H a rv estin g B lack R a sp b e r r ie s
at D iffe re n t In te r v a ls A fter Rain on Ju ly
11 and 12, 19:1 ..........................................................................................

78

E ffe c t of Shaking B u sh es on M old Count
of B e r r i e s .........................................................................................................

80

E ffec t of Holding W et B e r r ie s fo r Z e r o ,
S ix , and T w elve H ours
at 76° to 78° F .................................

81

E ffe c t of H olding D ry 31ack R a sp b e r r ie s
fo r Z ero , S ix , and T w elve H ours at 76°
to 78° F .................................................................................................................

82

E ffec t of W ashing w ith W ater on M old
Count of B la ck R a s p b e r r i e s ............................................................

83

M ea su r em en t of M old in B la c k R a sp b e r r ie s
E stim a te d by O rig in a l Howard M ethod and
M odified T e c h n iq u e ..................................................................................

84

E ffe c t of D iluting B la c k R a sp b e rr y P ulp
w ith P e c tin Solu tion ...............................................................................

8i

v ii

LIST OF FICtURES

F ig u r e

Pa'»e

u

t_»

1.

R e r jre ssio n of m o ld

count on tim e a fte r r a i n .....................

33

2.

R e g r e s s io n c f m old

count a fte r r a i n ............................................

39

3.

H isto g r a m of the m old count cf b e r r ie s
h a r v e s te d b e fo r e and a fte r shaking the b u s h e s ................

45

R e g r e s s io n o f m e ld count of w et and dry
b e r r ie s ov. holding t i m e .............................................................................

47

E ffe c t of w ash in g tr e a tm e n t on the m old
count in b e r r i e s ...............................................................................................

54

4.

5.

6.

E ffe c t of w ash in g tr e a tm e n t on m o ld count

7.

R e g r e s s io n of m old

8.

........................

55

............................

58

E ffe c t of addinrj d iffe r e n t am ou n ts o f p e c tin
so lu tio n on m o ld count ............................................................................

62

count on le v e ls

v iii

m old

INTRODUCTION

ilie prod u ction of black r a s p b e r r ie s
in the State of M ichigan; a p p r o x im a tely
p r o c e s s e d in the y e a r

1949.

This

is an im portant in d u stry

180,000 c a s e s

(No. 2) w ere

r e p r e s e n te d about 80 p er cen t of

the total p r o c e s s e d black r a s p b e r r ie s

of the United S ta tes

(21).

A

su b sta n tia l p o r tio n of the h e r r ie s f o r fr e e z in g w ere a lso grow n in
M ichi gan (21).
S e v e r a l sh ip m en ts of canned and fr o z e n black r a s p b e r r ie s
w ere

s e iz e d by the U nited S ta tes G overnm ent in 1949 and 1950 under

the F e d e r a l F o o d , Drug,

and C o sm etic A ct (9).

as being a d u ltera ted b e c a u se

of e x c e s s iv e

They w ere condem ned

m old count.

The p r o c e s s o r s

w ere a d /is e d that canned or fr o z e n blac^. r a s p b e r r ie s w ith high m old
counts could not be sh ip p ed o r so ld in in te r sta te c o m m e r c e .
r e q u ir e m e n ts of the la w and the p r e s e n c e
p o sed a s e r io u s

The

of high m old counts has

th rea t to the b lack r a sp b e r r y in d u stry in M ichigan,

and, as a r e s u lt , the p rod u ction dropped to about 140,000 c a s e s in
1910

(2 1 ).

P rocessors

c la im

that the w ea th er con d ition s in M ichigan in

1950 during the la tte r p a r t of the grow ing s e a s o n tended to be

1

fa v o ra b le fo r the d ev elo p m en t of m old on the fr u it in the fie ld , thereby
m aking it d ifficu lt to produce a product having a E ufficiently low m old
count to m e e t g o v ern m en t s p e c if ic a t io n s .
among in v e s tig a to r s
e s s e d product.

H ow ever, th ere is a co n flic t

about the c a u se of a high m old count in the p r o c ­

I f e ls e l and E ise n b e r g {13) b e lie v e d that poor quality,

such as o v e r r ip e

cr d e c o m p o sed black r a s p b e r r ie s , r e s u lts in a p rod ­

uct having a high m old count.

F abian e t a l . (8) sta ted that the p r e s ­

en ce of a high m old count of 60 p e r cen t p e r ten s a m p le s , or ?6
p e r cen t fo r one sa m p le , is not in d ic a tiv e of fr u it d eco m p o sitio n , as
th ey found sound b e r r ie s that had a high m old count.

They a lso r e ­

p orted a r e la tio n sh ip b etw een the w ea th er con d ition s during h a r v e s t ­
ing the b e r r ie s

and the m old count.

The m old count in c r e a s e d as

the tem p era tu re and h um idity in c r e a s e d .
The author f e lt that th ere was a n eed fo r fu r th er study to
d e te r m in e the fa c to r s

that m ight in flu en ce the m old count of p r o c e s s e d

b lack r a s p b e r r ie s .
This in v e stig a tio n w as c a r r ie d out in the v ic in ity of L aw rence
and K e e le r , M ichigan.

A study w as m ade of the m old count at v a rio u s

sta g e s o f m a tu r ity of the b e r r ie s , under d iffe r en t w ea th er con d ition s.
The e f f e c t of d iffe r e n t m ethods of w ashing the h a r v e ste d fru it w as
stu d ied a ls o , and a stu d y w as m ade to d ete r m in e the d iffe r e n c e s that
o c c u r in the m old count when v a r io u s dilution m ethods w ere u sed .

LITERATURE CITED

M olds are of eco n o m ic

im p ortan ce not only b e c a u se of th e ir

value to in d u stry and m e d ic in e , but a ls o b e c a u se of the dam age they
ca u se

to food and o th e r p ro d u cts.

M old s, a group of the fungi, are

m ic r o s c o p ic o r g a n is m s , sim p le in m o rp h o lo g ica l str u c tu r e , w ithout
d iffe r en tia tio n of body into true r o o ts , flo w e r s , o r v a sc u la r b u n dles.
They are d ev o id of ch lo ro p h y ll, and are d istin g u ish ed by a branched
netw ork of fila m e n ts o r th read s known as hyphae.
and fungi have rath er s p e c ific

m eans by w hich they p en etra te the

h o st and r e la te th e m s e lv e s to the h o st t is s u e .
tis s u e

M ost b a c te r ia

They e n te r the h o st

through natural o p en in g s, through w ounds, or by d ir e c t p e n e ­

tration (33).

B e r r ie s , lik e o th er fr u its and v e g e ta b le s , are n a tu ra lly

p ro te c te d a g a in st m old s by a la y e r of skin w hich has to be broken
o r d is s o lv e d b efo re the n u trien ts in sid e the fr u it b eco m e
to the o r g a n is m s .

availab le

S la te , B raun, and M undinger (26), and F ab ian

e t a l. (8) r e p o r ted that m ech a n ica l injury of the skin o f b e r r ie s

is

one of the m o st com m on m ean s by w hich m olds en te r and ca u se
d eca y .

L oree

(19) sta te d that so ft b e r r ie s

a re attack ed by m o ld s.

qu ick ly b reak down and

A lte r n a r ia h u m lco la O udem ans and C ladosporlum

ep ip h yllu m P e r s o o n w e r e

rep orted by Bene.ce (2) to be the m o st c o m ­

mon m old s found in black r a s p b e r r ie s
P u lla r ia sp .,

(Rubus o c c id e n ta lis ). w hile

T rich o d erm a s p ., A s p e r g illu s

s p ., Q ospold s p ., M cn illa

c p ., and M ucor sp . w ere found l e s s freq u en tly .
fr u its

su ch as

r a s p b e r r ie s , b la c k b e r r ie s , and d e w b e r r ie s

to attack by the sa m e m olds

are:

In g e n e r a l, b e r r y
are

su b ject

(11).

Am ong the fa c to r s

a ffectin g the g erm in a tio n of fungous sp o r e s

(1) te m p e r a tu r e , (2)

m o istu r e , (3) oxygen , (4) the h y d ro g en -io n

c o n cen tra tio n , and ( 5 ) the v ia b ility c f the s p o r e s .

The growth r e ­

q u irem en ts fo r fungi w e r e r e v ie w e d by L illy and B arn ett (18), W alker
(33), C layton (4), D ugger (7), and L a u ritzen (17).

F a c to r s

S in c e ,
during the

in

that Influence the M old Count in B e r r ie s

the

grow ing

case
se a so n

of black

r a sp b e r r ie s,

the

tem p eratu re

is

the

for

the

near

optim um

growth

of m o ld s, the m o istu r e req u ired by m o ld s fo r germ in ation m ay be
supp lied e ith e r by rain or by the so ft m atu re fr u it, the a ir fu r n ish e s
adequate oxygen supply, the h y d ro g en -io n con cen tratio n of the fru it
i s su ffic ie n tly low to be fa v o r a b le fo r the

growth

of m o ld s, and as

s p o r e s a r e ubiguitous in n atu re, it is d iffic u lt to produce b e r r ie s
fr e e fro m m o ld s .

W eather p la y s an im p o r ta n t r o le in influencing

the m old count in blacr
in b e r r ie s

r a s p b e r r ie s

(8,

13, 28).

The num ber of m olds

was found to be in flu en ced by s e v e r a l fa c to r s , w hich are

d is c u s s e d b elow .

T e m p e r a tu r e .

M ic r o o r g a n ism s w hich bring about d ecay of

fr u its and v e g e ta b le s a r e

red u ced in grow th w ith the low erin g of t e m ­

p era tu re ''elow the optim um .

When th e se o r g a n ism s are grown on

su itab le m ed ia o v e r con stan t te m p e r a tu r e s, a c o r r e la tio n is
betw een rate cf growth and the te m p e ra tu re .
lie s b etw een 20° and 30°
grow th r a te s d e c lin e .

shown

F o r m any, the optim um

C ., w hile above and b elow the optim um ,

When the tem p era tu re is n ea r the optim um ,

the e n zy m a tic a c tiv ity and the rate of sp o re g erm in a tio n a re in c r e a s e d
(21).

Optim um te m p e ra tu re and grow th ra tes of a given s p e c ie s m ay

d iffe r on v a rio u s

s u b s tr a te s

A lt e m a r ia so la n i is fr o m
m um of 26° to 28°
and E ise n b e r g

(36).

The grow ing tem p era tu re range

a m inim um of 1° to 3° C ., to an o p ti­

C ., and a m axim um of 37° to 45°

(13), F abian e t a l . (8), and S tein k rau s

that m old grow th in b lack r a s p b e r r ie s

C. (18).

H e ls e l

(28) have rep o rted

was rapid at high te m p e ra tu re s

around 80°(±) F .

H um idity r e q u ir e m en ts fo r m o ld s .

The sp o r e s of m any s p e c ie s

of fungi w ill not g er m in a te u n le ss th ey are in co n ta ct w ith fr e e w a ter.

W ater is e s s e n t ia l to a c tiv a te c e r ta in en zy m e s y s t e m s , to initiate
o th er in ter n a l c h e m ic a l ch a n g e s, and to in c r e a s e
g erm in a tin g s p o r e s

of fungi (18).

S p o res

of som e

the volu m e of the
s p e c ie s of fungi

are cap ab le of g er m in a tio n on dry su r fa c e s in an atm o sp h ere of high
h um idity, u su a lly 95 p er c en t o r above (18, 11).
of producing sh o r t g e r m
r e la tiv e h u m id ity (18).

O thers a re capable

tubes under con d ition s of e x tr e m e ly lowSnow, C hrichton, and W right (27) found the

m eld grow th on lo c u s t b ea n s, S co tch b e a n s, bran, o a ts, b o n em ea l,
and lin s e e d caice in sto r a g e w as m o re dependent on r e la tiv e hum idity
than on m o istu r e

con ten t of the food, and at 75 to 100 p e r cent r e la ­

tive h um idity the m old s grew rap id ly.

F ab ian e t a l. (8), Steinkraus

(28), and H e ls e l and E ise n b e r g (13) sta te d that, in black r a s p b e r r ie s ,
m old counts in c r e a s e d in hum id w ea th er and w arm te m p e ra tu re s.
The fo r m e r two authors m en tion ed that m old counts in b e r r ie s w ere
low in hot and dry w ea th er.

S tein k rau s

(28) sta te d that the m old

count in black r a s p b e r r ie s in c r e a s e d rap id ly during rain y w eather.
F abian e t a l . (8) sta te d that m o is t w ea th er fa v o r s m old growth by
supplying w a te r b etw een the c r e v ic e s of d ru p elets w here the m old
sp o r e s

are lod ged .

A lso , th ey sta ted that the o sm o tic a ction r e s u lt ­

ing fr o m the p r e s e n c e of m o istu r e on the su r fa c e of the b e r r ie s
b rin gs n u trien ts out of the rip e b e r r ie s fo r the grow th of m old s p o r e s .

In c r e a se d am ounts of w a ter into d ru p elets c a u s e s them to break d u r­
ing handling, and a ls o f a c ilit a t e s

the breakdow n of the skin of the

d ru p elets by the en zy m e

of m o ld s.

pea.

s y s te m

They found that, at the

of the black r a s p b e r r y p r o c e s s in g p er io d , m old counts in c r e a se d

on b e r r ie s

when the h u m id ity in c r e a s e d due tc r a in fa ll.

and M undinger (26) sta ted that during w et s e a s o n s

S la te , Braun,

m any g r o w ers

a r e tro u b led with fr u it ro t and v a r io u s m o ld s, such as B o tr y tis sp .,
F u sa r iu m

s p ., and A lt e m a r ia s p ., w hich m ay ca u se the fr u it to rot

ju st about the tim e that it b e c o m e s

rip e.

H e ls e l and E ise n b e r g (13)

rep o rted that a m o is t en v iro n m en t along w ith w arm tem p e ra tu re s
fa v o red grow th of m o ld s and o th er m ic r o o r g a n ism s w hich d e co m p o se
the b e r r ie s , and a ls o that the rain s p rev en ted p icking the b e r r ie s at
s u ffic ie n tly freq u en t in t e r v a ls , r e su ltin g in the fr u it b ecom in g o v e r rip e
and d e co m p o sin g on the b u s h e s .
that r a s p b e r r ie s b e co m e

D arrow and Waldo (5) m en tion ed

so ft due to ra in y w ea th er, and are

su b ject

to d ecay by m old fungi.

M atu rity of b e r r ie s
p orted by L o r e e

and it s e f fe c t on m old cou n t.

It was

re­

(19) and Dodge and W ilcox (6) that so ft b e r r ie s break

down e a s ily and th e r e fo r e

a re attacked by m o ld s.

H e ls e l and E is e n ­

b erg (13) sta ted that so ft rip e black r a s p b e r r ie s have h igh er m old
counts than fir m

rip e b e r r i e s .

F ab ian e t a l. (8) found h ig h er m old

counts in fir m
b e r r ie s
(22)
fr o m

rip e black r a s p b e r r ie s

in so m e c a s e s than in the

of m e r e advanced sta g e s of m atu rity.

N eedham and F e lle r s

r e p o r ted that a m o d e r a tely high m old count m ight be obtained
so ft, m ushy, o r o v e r r ip e blacr. b e r r ie s w hich show ed no v is ib le

ev id e n ce
b e r r ie s
fru it.

of m old.

D arrow and Waldo (5) sta ted that so ft, o v e rrip e

w e r e a tta ck ed e a s il y by fu n gi w hich c a u se d d eca y of the
R en d ell (2.r;) rep o rted that fo r ty -e ig h t hours w as a m p le, even

under a v e r a g e w e a th e r c o n d itio n s, in Scotland fo r the r a s p b e r r ie s to
change fr o m

a d e c id e d ly unripe sta te to one of m atu rity or r ip e n e s s ,

and a ls o that the ch an ges a s s o c ia t e d with ripening continued even
f a s t e r a fte r the fr u it was a ctu a lly p ick e d .
b e r r ie s

He a lso found that lo g a n ­

rip en ed m o r e q u ick ly than oth er v a r ie t ie s , and o c c a s io n a lly

ch an g es w e r e

so rapid that b e r r ie s

in red sta g e turned black and

s h r iv e lle d the n ex t day.

E ffe c t of h a r v e s t on m old count.

R a s p b e r r ie s, b eca u se of

th e ir p e r is h a b le n a tu re , req u ire v e r y c a refu l handling.

The m o st

com m on c a u se of d eca y is m e c h a n ic a l injury r esu ltin g fr o m c a r e le s s
handling during h a r v e stin g of the fr u it (8).

B e r r ie s injured or b r u ise d

in handling a re su b je c t to attack by m old fungi w hich c a u se d eca y (5).
S p e c ia l c a r e sh ou ld be taken to rem o v e the b e r r ie s fro m bu sh es
w ithout b reaking o r cru m b lin g them , and on ly a few b e r r ie s

should

be h eld in the hand at a tim e , to avoid h r u isin g .

The b e r r ie s

should

not be p ick ed when w et u n le s s fo r im m ed ia te u s e , as they m old
q u ick ly, e s p e c ia lly in w arm w ea th er.

Ripe b e r r ie s le f t on the bushes

b eco m e s o ft and are c e r ta in to c a u se trouble in la te r p ick in gs
H e ls e l and E ise n b e r g

(13)

sta ted that, with p ro p er handling, the m old

count of black r a s p b e r r ie s

could be red u ced , w hile F abian et a l. (8)

r e p o rted that p r o p e r handling of the b e r r ie s
in red u cin g the m old count.
the r a s p b e r r ie s

( 19 ).

L o ree (19)

did not m a te r ia lly aid

reco m m en d ed h a rv estin g of

on a lte r n a te days during the peak of the se a s o n .

D arrow and Waldo (5) sta te d that p icking of the r a s p b e r r ie s m u st
be done at le a s t two o r th r e e tim e s ea ch w eek , depending on lo c a lity ,
v a r ie ty , and w e a th e r c o n d itio n s.

H a rv estin g of r a s p b e r r ie s

m ay be

r e q u ired at le a s t e v e r y o th e r day in hot o r w et w ea th er, and on e v e r y
third o r fou rth day in d ry reg io n s of the W est (5).
M undinger (26) sta te d that under n o rm a l conditions

S la te , 3 r a u n , and
r a s p b e r r ie s

should

be p ick ed on a lte r n a te days; in v e r y hot w ea th er, e v e r y day; and
once in th ree days if the w ea th er is

H olding of b e r r ie s

co o l.

and its e ffe c t on m old count.

It w as r e ­

p o rted b y Dodge and W ilco x (6) that d ela y beyond a few hours b e ­
tw een picking and s a le to the c o n su m e r afford s an opportunity fo r
the d ev elo p m en t of fr u it r o ts and m o ld s in r a s p b e r r ie s .

L o ree (19)

10
a d v ise d that b e r r ie s

should be kept out of the h ea t of the sun a fter

they have b een p ick ed .
b lacl

r a s p b e r r ie s

H e ls e l and E ise n b e r g

(13) sta ted that sound

p ick ed during ra in y w ea th er could be h eld fo r a

r e a so n a b le len gth of tim e w ithout an ap p recia b le in c r e a s e in the m old
count.

F ab ian e t a l . (8) found a h ig h ly sig n ific a n t in c r e a s e

in the

m old count of b lack r a s p b e r r ie s by holding the b e r r ie s fo r v a rio u s
len gth s of tim e under w arm , hum id co n d itio n s.

S te v en s and W ilcox

(29), wo r .ing with Rhi '.opus rot of s tr a w b e r r ie s , found an in c r e a s e
in d e c a y cf ’ e r r i e s

that had b een w ash ed , and then d ried by ex p osu re

to su n ligh t.

W ashing and s o r t in g .

It w as rep o rted by Steinkraus (28) that

w ashing and so r tin g p r o c e d u r e s during the p r o c e s s in g op eratio n of
b lack r a s p b e r r ie s h elp ed in reducing the m old count.
(8) did not find s ig n ific a n t d e c r e a s e s
by w ashing them .

F abian e t a l.

in m old count of the b e r r ie s

H aynes and h is c o -w o r k e r s

(12) found sig n ific a n t

d e c r e a s e s in m old count of s tr a w b e r r ie s by trea tin g them w ith w ater
p ressu re

and d e te r g e n ts .

Howard (14) a d v ised that p rop er so rtin g

and w ash in g p r o c e d u r e s w ould help in reducing the m old count of
to m a to e s .

11
M old Counting

At the beginning of th is cen tu ry , the m anufacture of v a r io u s
tom ato p rod u cts becam e
w ere

c o m m e r c ia lly im portant.

As a r e s u lt, th ere

ra d ica l ch an ges in so m e of the m anufacturing m eth od s, w hich

tended to p rod u ce a c le a n e r and m o r e w h o leso m e product.

F o r the

pu rp ose of giving the m an u fa ctu rer a m eans of com paring the v a rio u s
m ethods of handling the p r o d u c ts, Howard (14) introd u ced a m ethod
fo r d eterm in in g the quality cf a tom ato pulp or catchup.
the p r o c e s s o r s

He f e lt that

handled the p roduct in su ch a way as to allow the

d eco m p o sitio n of the p roduct by b a c te r ia , y e a s t s , and m olds to o c c u r
at som e tim e during p r o c e s s in g , though the m a te r ia l m ight be r e la ­
tiv e ly fr e e fr o m d ecay ed o r putrid m a te r ia l.

P r e s c o tt , B u rra g e,

and P hilbuck (24) and D arlin g and B itting and B itting (cited by Fabian
e t a l ., 8) c r it ic is e d the p r o c e d u r e s u sed .
c o n cern ed the follow ing:

T heir c h ie f c r it ic is m s

(1) the d iffic u ltie s and s o u r c e s of e r r o r in

d istin g u ish in g b etw een plant t is s u e s and m ic r o o r g a n ism s at low m ic r o ­
sc o p ic m agn ification ;

(2) only the rod -typ e b a c te r ia w ere counted,

w h ile the c o c c u s fo r m s w e re ignored; (3) y e a s ts and m old sp o r e s
w ere counted to g eth er, sin c e th ey could not be d istin g u ish ed from
each other; and (4) the m ethod fa ile d to d istin g u ish betw een la r g e
m a s s e s of hyphae and one hypha in the fie ld .

B itting and B itting

{cited by F abian e t a l .. 8) a lso re p o rted that no rela tio n e x is te d b e ­
tw een the n um ber of o r g a n is m s and the d e c o m p o sitio n of the product,
sin c e the num ber of o r g a n is m s w as not alw ays co in c id e n t with p u tr e ­
fa c tiv e a c tiv ity .
Many attem p ts w e r e

made tc im p ro v e the Howard m ethod.

Vinci nt. (32) sta te d that the d ir e c t m ethod of counting b a c te r ia d e v ise d
by P r e s c o t t and B r e e d in

1911, w hich a ls o

is d e sc r ib e d in Standard

M ethods of B a c te r io lo g ic a l A n a ly se s of M ilk (APHA,
the s o u r c e s of e r r o r .

1916), e lim in a te s

The advantages of this m ethod are:

(1) the

b a c illi can be d istin g u ish e d fro m c o c c i o r in e r t m a te r ia l, w hile doubt
is

often en co u n tered when using the Z e is s counter; and (2) c o c c i can

be counted, sin c e they a re
th is m ethod is

u sed .

sta in ed e a s ily and can be o b se r v e d when

B a r t e r e lli and M a r ch elli (1) su g g e ste d a m o d ifi­

ca tio n of both the Howard and V in cien t m eth o d s, in w hich the tom ato
product w as d ilu ted , f ilt e r e d , and the filtr a te fix e d w ith a lc o h o l-e th e r
and sta in ed w ith B o e f f le r 's m eth y len e blue b efo re it w as
to m ic r o s c o p ic count.

su b jected

A nother m o d ific a tio n of the Howard m ethod

w as su g g e ste d by M ille r (20), in w hich the tom ato pulp w as b o iled
w ith L io effler’s m eth y len e blue and Z ie h l- N e e ls e n 's carb ofu ch sin .
With this p ro ced u re the m ic r o o r g a n is m s

a re sta in e d a d e ep er c o lo r

than the tom ato t is s u e s , and in addition to th is d iffe r e n tia l e ffe c t the

13
com b in ation of the two s ta in s fa c ilita te the d iffe r en tia tio n o f y e a s ts
from m o ld s p o r e s and b a c te r ia .
v a lid fo r M ille r 's

H ow ever, the sam e

c r it ic is m s are

m ethod as fo r the Howard m ethod.

U sin g the Howard m old count p ro ced u re on black r a s p b e r r ie s ,
S tein .raus ( 28) found that when the s a m p le s w e r e d ilu ted beyond a
o n e -to -o n e

ratio w ith p e c tin so lu tio n th ere was a d e c r e a s e in m old

count, but that th is d e c r e a s e w as not in d ir e c t p rop o rtion to the d ilu ­
tion.

The slo p e o f the d ilu tion cu rv e w as found to be g r e a te r if the

in itia l m old count w as h ig h er.

Standards fo r the N um b er of M olds
A llow ed in F oo d P r o d u cts

The F e d e r a l F ood, D rug, and C o sm e tic A ct of 1906 sta te s
that a food p rod u ct is d eem ed ad u lterated " if it c o n s is t s in w hole o r
in part of a filth y , d e c o m p o se d o r putrid anim al o r v e g eta b le su b ­
sta n c e "

(31).

F iv e y e a r s a fte r the e n a ctm en t of th is act, Howard

(14) in trod u ced the f i r s t standards fo r the m axim um num ber of m o ld s,
y e a s t s , and b a c te r ia to be a llo w e d in tom ato products; under th is
standard a tom ato p rod u ct w as to be condem ned if m olds w e r e p r e s ­
ent in m o re than 25 p e r c e n t o f the m ic r o s c o p ic f ie ld s , tw e n ty -fiv e
y e a s ts and s p o r e s in 1 / 6 0 m illilit e r , o r tw e n ty -fiv e m illio n of b a c ­
te r ia p e r m illilit e r .

In 1916 th is w as m o d ified to p e r m it 66 p er

14
cent of m o ld s in the m ic r o s c o p ic fie ld s

(3);

125 y e a s t s and s p o r e s

1/60 m illilit e r , o r one hundred m illio n b a c te r ia p e r m illilit e r .
and S tephenson (15) show ed th ere w as a v e r y c lo s e
tw een the am ount of sp o ila g e of tom ato products
o r s u p e r fic ia l so rtin g of the to m a to e s.

in

Howard

r e la tio n sh ip b e ­

and fau lty clea n in g

T ice (cited by F ab ian e t a l.,

8) sta ted that when to m a to es w ere p r o p e r ly handled the m old count
was of g r e a te r im p o rta n ce in judging the condition of the product
than the counts of o th e r m ic r o o r g a n is m s .
A cco rd in g to FDA stan d ard s during

1931, the tom ato products

w ere lim ite d to 50 p er cen t m old count; in 1938 a change w as made
w hich lim ite d the m old count in tom ato ju ic e to 25 p e r cen t.

Stand­

ards fo r catchup, p u r ee , and p a ste w ere changed to 40 p e r cen t m old
count and 15 per cen t fo r tom ato ju ic e in 1940, but la te r in the
sa m e y e a r FDA r a is e d the lim it s of m old count to 20 p e r cen t fo r
tom ato ju ic e , w h ile retain in g 40 p e r cent f o r the o th er tom ato p rod ­
u ces

(8).

A p p lication of Howard Method to B e r r ie s

Although the m old count p ro ced u re o r ig in a lly was d e sig n ed
fo r tom ato p r o d u c ts, it has been u se d fo r a g r e a t num ber of fo o d s,
including red and black r a s p b e r r ie s .

The a p p lica tio n of the Howard

m old count m ethod to b e r r ie s and b e r r y p roducts w as f ir s t su g g e ste d
by Ifeedham and F e lle r s

(22).

At the p r e s e n t tim e an u n o fficial

m old standard fo r black r a s p b e r r ie s
catchup.

is

50 p e r cen t, the sa m e as for

F ab ia n e t a l . (C) su g g e ste d that black r a s p b e r r ie s , b eca u se

of th e ir str u c tu r e , should have a standard of th e ir own and should
not be judged a cco rd in g to the standards of oth er p ro d u cts.

They

r eco m m en d ed 76 p e r cen t m eld count if one sa m p le w as u sed as a
r e p r e s e n ta tiv e cf a le t , o r 60 p e r c e n t if at le a s t ten sa m p le s w ere
taken and a v er a g ed .

H e ls e l and E ise n b e r g

(13) recom m en d ed that it

should not e x c e e d 10 p e r c en t, even under a d v e r se co n d itio n s.

EXPERIM ENTAL PROCEDURE

D uring the s e a s o n s o f 1951 and 1952 fro m fa r m s in the v ic in ity
of L a w ren ce, M ichigan, b la ck r a s p b e r r ie s
and put in c le a n quart b e r r y b o x e s.

w e r e c a r e fu lly h a r v e ste d

Som e e x a m p les were

at K e e le r , M ichigan, during the s e a s o n of 1952.

a ls o obtained

The h a r v e ste d b e r ­

r ie s w ere taken d ir e c tly to the fa c to r y , tr a n s fe r r e d to c le a n ca n s,
c o v e r e d , and fr c /e r i.

S in ce the m old counts could not be m ade con ­

c u r r en tly with h a r v e s t, blac,-; r a sp b e r r y sa m p le s obtained n e a r Law ­
ren ce w ere fr o z e n in the L a w ren ce F r o z e n F oods f r e e z e r , and th ose
c o lle c te d at K e e le r w e r e fr o z e n in the deep f r e e z e at B urnette F a r m s
P acking Com pany, and la te r tr a n s fe r r e d to L aw rence F r o z e n F oods
fr e e z e r .

A ll the fr o z e n sa m p le s of black r a s p b e r r ie s w ere brought

by r e fr ig e r a te d truck to the H orticu ltu re D epartm en t of M ichigan State
C o lleg e and sto r e d at 0° F . until th ey w e r e ex a m in ed .

E x p e r im e n ta l P lan

1.
black r a s p b e r r ie s .

E ffect of the sta g e of m a tu rity upon the m old count in
S a m p les of black r a s p b e r r ie s w er e h a r v e ste d at

the follo w in g s ta g e s of m aturity:

16

(1) S h in y-b lack :
d r u p e le ts.

sh in y -b la c

with o c c a sio n a l red

V e r y sound fru it.

(2) D u ll-b la ck :
c r e v ic e s

F ir m - r ip e ,

D ull ap p earan ce, h airs m ore p rom in en t in

betw een d r u p ele ts than in the sh in y -b la ck sta g e , f ir m e r than

so ft ripe fr u it.
(3) Soft ripe:
(4) C om p osite:

F r u it in v e r y advance stage of r ip e n e s s .
A g g reg a te sam p le of a ll the above s ta g e s of

m atu rity.

2.

E ffe c t of h a r v e stin g black r a s p b e r r ie s a fte r r a in fa ll.

Sam ­

p le s of b e r r ie s at e a c h sta g e of m atu rity, as w e ll as a co m p o site
sa m p le , w ere c o lle c te d fr o m eig h t d iffe r en t f ie ld s .

T hese w er e taken

th irteen , se v e n te e n , tw e n ty -fo u r , fo r ty -e ig h t, and se v e n ty -tw o hours
afte r r a in fa ll.
S a m p les w e r e a ls o c o lle c te d fr o m

ten d iffe r en t fie ld s at each

of the s ta g e s m entioned above when th ere had b een little o r no rain
fo r four d a y s.

3.

E ffe c t of shaking the b u s h e s .

S a m p les of ea ch sta g e of

m atu rity w e r e c o lle c te d fr o m Logan and C um berland v a r ie t ie s .
the b u sh es fr o m w hich th ese

Then

sa m p le s w ere taken, w ere shaken, and

another s e t of s a m p le s c o lle c te d .

18

The m old count fo r e a c h s e t of sa m p le s w as d eterm in ed and
a c o m p a r iso n w as m ade b etw een the num ber of m olds in the b e r r ie s
of the two v a r ie t ie s

te s te d .

A lso , a co m p a r iso n betw een the r e s u lts

obtained b efo re and a fte r shaking the b u sh es w as m ade.

4.

E ffect of holding black r a s p b e r r ie s .

On Ju ly 17, 1952, s ix

lo ts of d ry black r a s p b e r r ie s w e r e c o lle c te d fro m s ix d ifferen t f ie ld s ,
and e a c h was d iv id ed into th ree p o r tio n s.

One was fr o z e n im m e d ia te ly ,

another a fte r holding fo r s ix hours at 76° to 78° F ., and the la s t one
a fte r holding under the sa m e con d ition s fo r tw elv e h o u r s.
m ent w as r ep e a ted fo r b e r r ie s h a r v e ste d on Ju ly 21,

This tr e a t­

1952.

S im ila r e x p e r im e n ts w e r e conducted fo r black r a s p b e r r ie s
h a r v e ste d im m e d ia te ly a fte r rain on July 18 and 23,

5.

E ffe c t of d iffer en t m eth od s of w a sh in g .

b e r r ie s fr o m th ree

1952.

F our sa m p le s of

reg u la r r e c e ip ts o f a M ichigan food p r o c e s s o r

w ere taken at the end of the s e a s o n in 1952 and su b jected to three
kinds of w a te r -p r e s su r e w ash in g to d eterm in e the e ffe c t of w ashing
on the m old count of b e r r ie s .

The fr u it obtained from a sh a k e r -s p r a y

w ashing w as tarcen as a c o n tr o l.

The d iffer en t w ashing trea tm en ts

u sed w ere sh a k er and sp r a y w ash in g, sh a k e r and sink w ashing, and
sh ak er,

sp ra y , and sink w ash in g.

19
6A.
fied m ethod.

C o m p a riso n of o ffic ia l m old count m ethod with the m o d i­
F o r th is study, pulp of s e v e n ty -fiv e

sa m p le s of b e r r ie s

w as dilu ted with 3 p er cen t p ectin so lu tion in the ratio of 1:1 a c c o r d ­
ing to the o r ig in a l H oward m o ld -c o u n t m ethod, and the per cen t of
m old in the m ic r o s c o p ic f ie ld s in each sa m p le w as reco r d e d .

Then

the m ix tu r e of pulp and p ectin solu tio n w as fu rth er diluted with 3 per
cen t p ectin so lu tio n to 2:1, and the m old count in each sa m p le w as
re c o r d e d .

6B.
black

E ffe c t of d ilu tion on m old count.

S ix ty -tw o sa m p le s of

r a s p b e r r ie s containing fro m 20 to 100 per cen t m old cou n ts,

a s d e te r m in ed by the m o d ified tech n iq u e, w ere taken to study the e f ­
f e c t of d ilu tion w ith 3 per cen t p ectin so lu tio n on m old count of the
b e r r ie s .

The m ix tu r e of black r a sp b e r r y pulp and 3 p er cen t p ectin

so lu tio n m ade fo r o b se r v a tio n of m old count w as d iluted with pectin
so lu tio n to bring the ra tio of p ectin to pulp to 1:1, 2:1, 4:1, 6:1, 8:1,
10:1,

12:1, and 14:1, and the per cen t of m o ld s in the b e r r ie s d e t e r ­

m in ed a t each le v e l of d ilu tion .
A su m m ary of the e x p e r im e n ta l plan i s given in Table I.
o ffic ia l w eath er data fo r J u ly, 1951 and 1952, a r e su m m a riz e d in
T able II.

The

20
TABLE I
EXPERIM ENTAL PLA N

Code
Sam ple

Date of
Sam ple
C o lle c tio n

N o . of
S a m p le s

E x p erim en t

1.

T re atm ents

E ffe c t of M aturity on the Mold Count
of B e r r ie s

E x p erim en t 2a.
E ffe c t of H a rvestin g A fter R ain at
D iffe rent D aily In ter v a ls
IB a - J

40

7/13/51

I3 a -2

40

7/14/51

IB a -3

20

7/15/51

IB a - 4

20

7/16/51

Ii3a-5

20

7/17/51

C o lle c ted 1
h a r v e st.
C o lle c te d 2
h a r v e s t.
C o lle c te d 3
h a r v e s t.
C o lle c te d 4
h a r v e st.
C o lle c ted 5
h a r v e st.

day a fte r p rev io u s
days a fte r p rev io u s
days a fte r p rev io u s
days a fte r p r e v io u s
days a fte r p rev io u s

E x p erim en t 2b.
E ffe ct of H a rv estin g A fter Rain at
D iffe r e n t H ourly In terv a ls
IBb- 1
IB b-2
I B b -3
IBb-4
IBb-5

32
32
32
32
32

7/15/52
7/15/52
7/15/52
7/16/52
7/17/52

C o lle c te d
C o lle c ted
C o lle c te d
C o lle c ted
C o lle c te d

at
at
at
at
at

13-14 h r s . after rain
17- 18 h r s . a fte r rain.
2 3 -2 4 h r s . a fte r rain.
4 8 h r s . a fte r rain.
72 h r s . a fter rain.

E x p er im en t 3.
E ffe c t o f Shaking B u sh es B e fo re
H a rv estin g the B e r r ie s
IC-1
IC -2
IC- 3
IC-4

24
24
24
24

7/13/51
7/13/51
7/13/51
7/13/51

L ogan v a r ie t y -- n o shaking.
L ogan v a r ie t y - - a f t e r shaking.
C um berland v a r ie t y -- n o shaking.
C um berland v a r ie t y - - a f t e r shaking

21
TABL.E I (Continued)

Code
Sam ple

N o. of
S a m p les

D ate of
Sam p le
C o lle c tio n

T reatm en ts

E x p er im e n t 4a.
E ffe c t of Holding the B e r r ie s
A fter H a rv estin g Wet
I D- A- 1

ID-A - 2

ID -A - 3

6

7/10/52

6

7/23/52

6

7/18/52

6

7/23/52

6

7/18/52

6

7/23/52

C o lle c te d a fte r
m e d ia te ly .
C o lle c ted a fter
m ed ia tely .
C o lle c ted a fter
hours b efo re
C o lle c te d a fte r
hours b e fo r e
C o lle c te d a fte r
hours b e fo r e
C o lle c te d a fter
hours b e fo r e

ra in , fr o z e n im ­
ra in , fr o z e n im ­
r a in , held
f r e e z in g .
rain , held
fr e e z in g .
ra in , held
fr e e z in g .
r a in , h eld
fr e e z in g .

fo r 6
fo r 6
fo r 12
f o r 12

E x p erim en t 4b.
E ffe ct of Holding the B e r r ie s
A fte r H a rv estin g D ry
I - D - B -1

I-D-3-2

I-D-B- 3

6

7/17/52

6

7/21/52

6

7/17/52

6

7/21/52

6

7/17/52

6

7/21/52

D ry b e r r ie s
holding.
D ry b e r r ie s
holdin g.
D ry b e r r ie s
holding.
D ry b e r r ie s
holdin g.
D ry b e r r ie s
holding.
D ry b e r r ie s
holding.

fr o z e n a fter 0 hours
fr o z e n a fter 0 hours
fr o z e n a fte r 6 hours
fr o z e n a fte r 6 hours
fr o z e n a fter 12 hours
fr o z e n a fter 12 hours

22
TABLE I (Continued)

Code
„
,
Sam ple

N o. of
„
.
S a m p le s

Date of
Z,
,
Sam ple
_ ,,
C o llec tio n

E x p erim en t 5.
IE-1
IE -2
IE-3
IE-4

12
12
12
12

7/18/52
7/18/52
7/18/52
7/13/52

T reatm en ts

E ffec t of W ashing
C ontrol.
C ontrol +sp r a y -w a sh e d .
C ontrol +sin k -w a sh ed .
C ontrol +sp r a y -w a sh e d + sin k w ashed.

E x p erim en t 6a.
E ffect of D iluting B lack R asp b erry
Pulp With P e c tin Solution
I3 b

1

8

7/15/52

IBb
I3b
I3b
IBb
IDA

2
3
4
5
1

1
5
8
8
3
.

7/15/52
7/15/52
7/15/52
7/15/52
7/23/52
7/18/52
7/23/52
7 / 2 3/ 52
7/17/52
7/17/52
7/21/52
7/17/52
7/21/52

IDA 2
IDA 3
ID3 1

2
2

IDB 2

5

IDB 3

5

IE
IE
IE
IE

2
4
3
2

HI

1
2
3
4

16

7/18/52
7/18/52
7/18/52
7/18/52
7/18/52
7/22/52

C om p arison of o ffic ia l m ethod with
m o d ified technique.

23
TAB jLE I (Continued)

Code
Sam ple

No. of
S a m p le s

Date of
Sam ple
C o llec tio n

Expe r im en t 6b.

T reatm en ts

E ffe c t o f D ilu tion s on Mold Count
P e c tin s o lu With above s a m p le s .
tion was added to bring the
ratio of p ectin to pulp as 4:1,
6:1, 8:1, 10:1, 12:1, and 14:1.

24
TABLE II
OFFICIAL WEATHER DATA FOR JULY,
IN PAW PAW , MICHIGAN
Tem pe rature
Date

D aily
P r e c ip ­
itation
(inches)

M ax.
i° F.)

Min,
<° f .)

7/1/51
7,2/51
7/3/51
7/4/51
7/5/51
7/6/51
7/7/51
7/8/51
7/9/51
7/10/51
7/11/51

74
80
81
78
75
85
88
80
83
85
78

53
51
56
58
50
47
58
63
63
62

62

0.03

7/12/51
7/13/51

77
82

58
56

0.10

7/14/51
7/15/51

84
86

55
59

7/16/51

88

58

7/17/51

80

56

7/18/51
7/19/51
7/20/51
7/21/51

87
83
80
86

60
57
46
63

1951,

P e r s o n a l O b serv a tio n at
L a w re n c e, M ichigan

0.25

0.02

0 .6 8
0. 87
Hot and s lig h tly hum id.
L ight sh o w ers in the afternoon
and h ea v y rain in the night.
Cool m orn in g, sh o w ers till noon
Cool m orning, slig h tly w arm in
the a ftern oon - -no rain.
W arm d a y --n o rain.
Hot sunny day, h ea v y dew in
the n igh t— no rain.
Hot sunny day, h ea v y dew in
the n ig h t--n o rain.
Cool in the m o r n in g --w a r m day.
H eavy dew in the n ig h t--n o
rain .
Hot and humid day.
Hot and humid day.
W arm and hum id day.
Cloudy and co o l day.
L ight
sh ow ers.
H eav y rain in the
night.

C lim a to lo g ic a l D ata (M ichigan) W. S. D ept. C o m m e rc e ,
W eather B u reau .

25
TABLE II (Continued)
Tem pe rature
M ax.
(° F.)

Min.
(° F.)

D aily
P r e c ip ­
itatio n
(inches)

7/22/£ 1

84

58

4.85

7/23/51
7/24/51

77
87

59
56

0. 03

7/25/51
7/26/51
7/27/51
7/28/51
7/29/51
7/30/51
7/31/51
7/1/52
7/2/52
7/3/52
7/4/52
7/5/52
7/6/52
7/7/52
7/8/52

88
89
85
79
85
90
82
89
89
83
90
92
94
89

59
62
65
54
62
58
67
60
68
67
57
53

7/9/52
7/10/52
7/11/52
7/12/52
7/13/52

75
84
85
95
92

47
52
61
69
68

7/14/52

87

70

Date

96

P e r s o n a l O b serv a tio n at
L a w ren ce, M ichigan

Cool day. S h ow ers in the m om
ing.
Cool night with h eavy
dew.
Cool day.
Hot and hum id.
H eavy dew in
the night.
W arm and hum id.

0.91

*

0.24

62
62

60

1.16

0.35

L ight rain t ill 2:00 p.m.
Then
it w as co o l f o r the r e s t of
the day.
S lig h tly w arm and hum id.
Warm and dry.
Hot and dry.
Hot and dry.
Hot and hum id, c o o l and c le a r
night.
Cloudy, rained h e a v ily at 4:30
p .m . and again fro m 5:45
p .m . to 7:00 p. m.

26
TABLE II (Continued)
T em p eratu re

D aily

M ax.
(° F .)

Min.
(° F .)

ita tio n
(in ch es)

7/15/52

73

63

0. 40

7/16/52

82

62

0. 23

7/17/52
7/18/52

84
89

68
72

0.85

7/19/52
7/20/52
7/21/52
7/22/52

85
92
90
98

70
68
77
68

0.15

7/23/52

92

66

0.50

7/24/52
7/25/52
7/26/52
7/27/52
7/28/52
7/29/52
7/30/52
7/31/52

84
86
84
90
86
78
77
77

53
55
70
55
65
47
55
45

0.10

0. 07
0. 2 3

P e r so n a l O b serv ation at
L a w ren ce, M ichigan

No rain w as o b se r v e d at K e e le r ,
L a w ren ce, o r Benton H arbor.
Cloudy in the m orning.
S lig h tly w arm and hum id.
Cloudy t i l l la te afternoon.
O c­
c a sio n a l sh o w e r s b etw een
8:30 a .m . and 1:00 p .m .
Sunny from 3:30 p .m . till
even in g.
W arm and hum id.
Rain in the m orn in g fr o m 6:00
to 8:00 a . m . , then w arm and
hum id day. S ligh t d r iz z lin g
at 3:00 p .m .
H eavy rain
fro m 4:30 to 11:00 p .m .
Cool m orn in g, w arm and hum id.
Hot and hum id.
Hot and hum id.
Hot and hum id.
L ight rain in
the ev en in g .
Rain fro m 5:00 to 8:00 a.m .
W arm and humid day.
Warm and dry.
W arm and dry.
Cloudy day.

27
M ethods of P r o c e d u r e

The fo llo w in g p r o c e d u r e s w e r e c a r r ie d out on e a ch sa m p le
u n le ss o th e r w ise sta ted .

Thawing o f b e r r ie s .

The c a n s containing black r a s p b e r r ie s

w ere kept in a co n ta in er holding b o ilin g -h o t w a te r .

In th is w ay thaw ­

ing of b e r r ie s cou ld be e a s ily attain ed within fifte e n to tw enty m in ­
u te s.

A ll the sa m p le s w e r e thawed in this m an n er, and then pulped.

P ulping o f black r a sp b e r r y s a m p le s .
for m ic r o s c o p ic

S a m p les w ere p rep ared

exam in a tio n by pulping the b e r r ie s w ith a la b o ra to ry

pulper* having s c r e e n op en in gs of 0. 027 in ch in d ia m e te r.

M ethod f o r m old counting.

One p art by w eigh t of the black

r a sp b e r r y pulp w as d ilu ted with two p a rts by w eig h t of 3 p e r cen t
p ectin so lu tio n .

The pulped b e r r y sa m p le s w e r e ex a m in ed f o r m old

fila m e n ts by the A .O .A .C . O fficia l m ethod (23).

A ll m old counts

re p o rted w ere b a sed on ex a m in a tio n of at le a s t one hundred m ic r o ­
sc o p ic f ie ld s .

T his m ethod was p r o p o se d o r ig in a lly and adopted by

H e ls e l and E ise n b e r g (13), b ec a u se the deep c o lo r and d e n sity of

C efa ly la b o r a to r y p u lp er.

28
pulp p r e p a re d fro m fr e s h and fr o z e n b e r r ie s

m ade m old counting d if­

fic u lt when p u re pulp w as u sed .
The d ilu tion technique d e s c r ib e d above is a m o d ifica tio n of
that d e s c r ib e d in the M ethods of A n a ly sis o f A.O. A.C.

(23), in w hich

the pulp w as d ilu ted w ith equal p a rts of 3 p e r cen t p ectin so lu tio n by
w eight.
The a ir bubbles in co rp o ra ted during pulping of fr o z e n r a s p ­
b e r r y sa m p le s w e r e e a s ily r e m o v ed by adding s m a ll am ounts of
antifoam

to the sa m p le and s tir r in g thoroughly with a g la s s

rod,

although the a ir bubbles in the sa m p le s could be e lim in a te d if the
sa m p le s w e r e a llo w ed to s e tt le about th irty m in u tes.

Howard (16),

w orking on the u se of d iffe r en t in str u m e n ts, w hile m aking a m ic r o ­
s c o p ic a l ex a m in a tio n fo r m old in tom ato p ro d u cts, found it b e tte r
to u se e ith e r a la r g e o r m edium s c a lp e l w ith pointed end fo r taking
the t e s t m a te r ia l a fte r s tir r in g .

P r e p a r a tio n of p ectin so lu tio n .
p ectin

(100 grade) w as p rep a red .

tille d

w a ter w as h eated in a

added

slo w ly in a sp rin k lin g m anner to

A 3 p e r cen t so lu tion of apple

One hundred m illilit e r s of the d i s ­

b ea k er on a hot p la te, and p ectin was
the liq u id , w hich w as agitated

A ntifoam m anufactured by Dow C h em ical Company.

sim u lta n e o u sly w ith a g la s s

rod.

A sm a ll am ount of antifoam was

added to the hot so lu tio n to avoid foam fo rm a tio n .
was c o o le d ,
lit e r s

5 m illilit e r s

A fter the solution

of 36 p e r cen t form ald eh yd e p e r

100 m ill i­

of so lu tio n w as added to p r e v e n t any m ic r o b ia l grow th in the

p ectin so lu tio n .

This addition of form ald eh yd e w as a slig h t m o d ific a ­

tion of the m ethod d e s c r ib e d in A .O .A .C . (2 3).

D ilution m ethod f o r e stim a tio n m old count in the b e r r i e s .
d ilutions of the sa m p le s w e r e m ade g r a v im e tr ic a lly .

The

F ifty g ra m s of

3 p e r cen t p e c tin so lu tio n was added to 50 gram s of black r a sp b e r r y
pulp in o r d e r to m ake a 1:1 ratio of p e c tin to pulp.

The sa m e m ix ­

ture w as d iluted fu r th e r to the d e s ir e d co n cen tra tio n by adding 3 p e r
cent p e c tin so lu tio n .

When the p e c tin so lu tio n w as added to the black

r a sp b e r r y pulp, the m ix tu re w as s t ir r e d thoroughly to make it u n i­
fo rm .

As the d ilu tion in c r e a s e d , the in te n s ity of c o lo r d e c r e a s e d ,

and it w as e a s i e r to ex a m in e the sa m p le s f o r m old count.

RESULTS

The ta b le s p r e s e n te d in the te x t su m m a r iz e the o r ig in a l data
which are g iv en in the Appendix.

E ffe c t of S tage of M aturity of B e r r ie s

Berries

on Mold Count

that w e r e h a r v e ste d in the sh in y -b la ck stage had an

av era g e m eld count of 4 . 0 ,

4.5,

5.5, 9.5, and 11.5 p er cent fo r the

tim e in te r v a ls cf th ir te e n , se v e n te e n , tw en ty -fou r, fo r ty -e ig h t, and
se v e n ty -tw o h ours a fte r ra in , r e s p e c tiv e ly .
b e r r ie s fo r a ll in te r v a ls

was

7 p e r cen t.

The m ean m old count in
The d u ll-b la ck b e r r ie s

w ere found to contain an a v e r a g e of 10.3, 7. 0,

13.5,

16.0, and 22.5

p e r c en t, r e s p e c tiv e ly , fo r the sa m e in te r v a ls w ith a m ean of 13.9
per cent; and the so ft b e r r ie s ,

35.8, 50.0, 47.3,

6l.0,

and 59.3 p er

cen t, r e s p e c tiv e ly , for the sa m e i n t e r v a l s , with a m ean of 50.7
yer cen t (T able III).
E xam in ation of Table IV show s that, as the b e r r ie s advanced
in m a tu rity fro m the sh in y -b la c k to the so ft-b la c k sta g e , the m old
count in c r e a s e d .

This in c r e a s e w as found to be highly sig n ific a n t,

and can be ex p la in e d by the fa c t that the sk in of the advanced m ature

30

31
TABLE III
AVERAGE MOLD COUNT OF BERRIES A T D IF FE R E N T STAGES
OF MATURITY, C O LLEC TED AT D IF F E R E N T INTERVALS
A F T E R RAIN, DURING THE 1952 SE A SO N 1
H ourly
In te r v a ls
S ta g e s

D aily
In te r v a ls

of M atu rity
13- 14
<%)

17-18
v%)

1 day
(%)

...............................

4.0

4.5

5.5

9.5

11.5

Dull

..................................................

10. 3

7.0

13.5

16.0

22.5

Soft

.................................................

35.8

50.0

47.3

61.0

59.3

24. 3

34.0

40.3

38.5

41.8

18.6

23.9

26.6

31.3

33.8

S h in y -b la ck

C o m p o site sa m p le
M ean value

. . . .

...............................

2 days
<%)

3 days
(%>

O r ig in a l data in Table XII (A ppendix).

b e r r ie s w as e a s i l y b roken o r d is s o lv e d by the m o ld s, so that w a ter
and n u trien ts b e c a m e a v a ila b le f o r the grow th of the m old.

The

c o m p o site s a m p le s w e r e found to contain an a v er a g e m old count of
24. 3,

3 4 .0 , 4 0 . 3 ,

38.5, and 41 . 8 f o r the p e r io d s of th ir te en , s e v e n te e n ,

tw e n ty -fo u r , fo r t y - e ig h t, and se v e n ty -tw o h ou rs a fte r rain, w ith a
m ean of 35.8 p e r c e n t.
to be alw ays

A v e r a g e s fo r c o m p o site s a m p le s w e r e found

s ig n ific a n tly lo w e r than that o f the s o ft rip e s t a g e , and

32
TABLE IV
AVERAGE MOLD COUNT OF BERRIES COLLECTED AT
D IF F E R E N T STAGES OF MATURITY, AND
ANALYSIS OF VARIANCE
A v era g e Mold Count of
ShinyB lack
<%)

D ull
(%)

Soft
(%)

C om ­
p o site
<%)

7.0

13.9

50.7

35.8

No. of
Sam ­
p le s

rIT
Value

160

5 7 .9 * *

L. S. D.
5%

3.7

1%

4. 88

H ighly s ig n ific a n t.

h igh er than that of the sh in y - and d u ll-b la c k sta g e s (T able IV).
rate of in c r e a s e

The

in the m old count of the c o m p o site sa m p le was

g r e a te r than the rate of in c r e a s e in the s o ft b e r r ie s — the d u ll-b la c k
or sh in y -b la c k b e r r ie s (F ig u r e 1).

The sh in y -b la ck had the lo w e st rate of

m old in c r e a s e w ith tim e , w hile the d u ll-b la c k r a s p b e r r ie s had the
next lo w e s t rate o f in c r e a s e .

The h ig h er rate of m old in c r e a s e

with tim e fo r the c o m p o site sa m p le m ay be the r e s u lt of m ixin g the
so ft f r u it - -w h ic h have high m old c o u n ts --w ith sh in y -b la c k and d u llblack fr u it having lo w m old co u n ts, and so giving the m old m ore
su r fa c e a r e a and m ed ia to grow upon.

A ls o , it is

com m on ly b e ­

lie v e d that the e m p ir ic a l m ethods fo r counting m o ld would give such

SoFt

■Co mp o si te S a t n f o l t

OuLL b l o c k

- shiny b t n c k
V -

I

J

X - l o fO./if-lC

34
r e su lts when soft fr u it having high m old count is m ixed with fruit
in other sta g e s of m atu rity containing a s m a l l num ber of m olds.
Data obtained s e e m to in d icate that the so ft b e r r ie s w ere r e ­
sp on sib le for the high m old count in the co m p o site s a m p le s.

E ffect of H arvestin g A fter Rain at D ifferen t Intervals

H ourly in terv a l s .
le c te d cn July

Is,

1952.

F o r this ex p e r im en t the sa m p les w ere c o l ­
E xam ination of Table II show s that on July-

12 and 13, p r i c r to the c o lle c tio n of s a m p le s , the tem p eratu re ranged
f rom 68° to 95° F . , with an a verage of 81° F .
the evening of the fou rteen th .

No rain fe ll untill

This p erio d w as not favorable for the

germ in ation and growth of m old s p o r e s .
teenth, the tem p eratu re ranged from

A fter the rain on the fo u r ­

62° to 84° F ., with an average

of 72° F . during the th r e e -d a y p erio d of sa m p le c o lle c tio n .

The

hum idity was high due to the ra in fa ll, and w eath er conditions during
this p erio d se e m e d to be fav ora b le fo r the growth of m old s.
E xam ination of Table V show s that the sa m p le s which w ere
c o lle c te d th irteen hours after rain had an a v era ge of 4.0, 10.3,

35.8,

and 24.3 per cent, r e s p e c tiv e ly , fo r the sh in y -b la ck , dull, so ft, and
c o m p o site s a m p le s.

35
TABLE \
ANALYSIS OF VARIANCE OF THE MOLD COUNT IN BERRIES
COLLECTED AT D IFFE R E N T INTERVALS A FTER RAIN1

A ve rage Mo 1d Count in
Stage of M aturity
13
Ir s .

17
h rs.

24
hrs.

4b
h rs.

..................................... ...

4.0

4.5

4.5

6.9

D u l l - b l a c k ............................................

10.3

7.0

12.4

20.8

S o ft-b la c k

35.8

50.0

61. 3

61.4

24.3

34.0

31.2

29.1

18.6

23. 9

27. 4

29.6

S h in y-b lack

.............................................

C om posite sam p le

Total a v era g e

. . . . . . .

..................................

O rigin al data in T ables XII and XIII (Appendix)
* S ign ifica n t.
* * H ighly sig n ific a n t.

36

TABLE V (Continued)

B e r r ie s
72
his.

{%)
,

96

No.
of

Sam ­
ple
F
V alue

L. S. D.

hrs,

120
h rs.

9. 5

2.4

4.0

2.602*

0. 52

16.3

2.4

4.0

3 .0 2 *

4,06

70.3

9.2

22.5

7 .3 9 * *

7.82

10.38

46.2

4. 8

8.4

6.11*

5.45

7.24

35.6

4.7

9.7

Sam ­

ples

75

5%

1%

The n ex t c o lle c tio n ,
average of 4.5,

7.0, 50. 0,

m aturity, r e s p e c t iv e ly .

se v e n te e n hours a fte r the rain , had an
and 34.0 p e r cent f or the sa m e

A n a ly sis of v a r ia n c e

sta g e s of

(T able V) in d icated that

there w as no sig n ific a n t d iffe r e n c e in the m old count of the sh in y black and d u ll-b la c k b e r r ie s

c o lle c te d b etw een th irte en and se v e n te e n

hours a fte r ra in , but that th ere w ere highly sig n ific a n t d iffe r e n c e s in
the so ft-b la c l; and c o m p o site

s a m p le s .

B lack r a s p b e r r ie s c o lle c te d

tw en ty -fo u r h ours a fte r rain had an a v era g e of 5.5,

13.5, 47.25, and

40.25 p e r c e n t f o r the sh in y -b la c k , d u ll-b la c k , so ft, and co m p o site
s a m p le s, r e s p e c tiv e ly .

A n a ly sis of v a r ia n c e

show ed that th ere w as

no sig n ific a n t d iffe r e n c e b etw een the m old count of sh in y -b la c k and
d u ll-b la c k b e r r ie s c o lle c te d tw en ty -fo u r hours a fte r rain and those
c o lle c te d th ir te e n hours a fte r rain .
e n c e s in the s o ft and c o m p o site
The r e g r e s s io n cu rv e
m old s in b la ck r a s p b e r r ie s
low ing

r a in fa ll.

There w ere

sig n ific a n t d iffe r ­

s a m p le s .

(F igu re

1) in d ic a te s that the num ber of

in c r e a s e s w ith the in c r e a s e

of tim e f o l ­

This w as m o re n o tic e a b le f o r the so ft fr u it and the

c o m p o site s a m p le s than fo r the sh in y -b la c k and d u ll-b la c k fr u it,
w here the in c r e a s e w as n e g lig ib le .

D ay in te r v a ls .

The a v er a g e m old count in the b lack r a s p b e r ­

r ie s one, tw o, th r e e , fo u r , and fiv e days a fte r rain w as 27. 4, 2 9 .6 ,

3<i
36.6, 4.7, and 9.7,

r e s p e c tiv e ly (T able V).

A n a ly sis of va ria n ce

show ed that th ere w ere s ig n ific a n t d iffe r e n c e s b etw een the m old
counts in b e r r ie s

a fter th e se in te r v a ls

n o ticea b le in c r e a s e

(Table V).

in m old count of the b e r r ie s

There w as a
up to the third day

after rain; then the m old counts d e c r e a s e d ra p id ly (F igu re 2).
was o b se r v e d that sh in y -b la c k b e r r ie s

It

took tw e n ty -fo u r hours to rea ch

the dull sta g e during the grow ing s e a s o n , and another tw en ty -fo u r
hours to b e c o m e soft.

On th is b a s i s , the m old count fo r the b e r r ie s

that w e r e sh in y black tw e n ty -fo u r hou rs a fte r rain in c r e a s e d fr o m
4.:

to 20. 8 p e r cen t a fter fo r ty -e ig h t h o u rs, w hich w as the count fo r

the d u ll-b la c k , and to 70. 3 p e r cen t sifter se v e n ty -tw o h o u rs, w hich
was the count fo r the s o ft b e r r ie s .

On the fou rth day, they s h r iv ­

el e d and d ried up, and so w ere e lim in a te d .

The sa m p le s c o lle c te d

on the fourth and fifth days r e p r e s e n te d the fr u its that w e r e in the
g r e en and red s ta g e s during the ra in y p e r io d , and so they m atured
under n o rm a l d ry con d ition s and m igh t be e x p e c te d to have lo w e r
m old count.

The data obtained during the fourth and fifth days c o r ­

respond w ith data p r e v io u s ly obtained during d ry co n d itio n s.
F rom

the r e s u lt s

obtained, the author f e e l s that the b e s t tim e

fo r h a r v e stin g the b e r r ie s in rain y w ea th er to g e t low m old count
would be as soo n as p o s s ib le a fte r ra in .

£

O

$

SN
<a

<£

§

<5>

I

I

I

/

/

I

*

K

II^&

fis

i

/$

I

* ,Q>

f^

|ii
m

U)
X

/

i'<f
MJ

I1So
-

-+>

N

/

U:

II
C\
•

l* °

/

x

§^

a

V.

,

N_

t

G

a

^

<
<s

&

£
G
>

i?
'i
16-

*

r
M

Q>

I
si

<?
O

w

A)
Go
X

* 0

II

/*

1$
!S
\

£

X

!i

.

\

r«

jfr

I?
<c

fv cc
c
Q

's

/
/
/
6£

O)

•v

c

r
C
rN
%
V

E ffe c t of V a riety on the Mold Counts

Data obtained (T able VI) show ed that the Hogan v a r ie ty b e r r ie s
had an a v e r a g e m old count of 12.7,

39.7,

87.0, and 79.7 p e r cen t fo r

the sh in y -b la c k , d u ll-b la c k , so ft, and co m p o site
The a v e r a g e s f c r

the C um berland v a r ie ty w ere

5 3.3 p er c en t fo r

the sa m e

s a m p le s ,

respecti/ely.

12.0, 24.0, 67.7, and

s ta g e s of m a tu rity. The b e r r ie s of

the

Logan v a r ie ty had sig n ific a n tly h ig h er m old counts than of the Cum ­
berland v a r ie ty at all the sta g e s cf m a tu rity e x c e p t the sh in y -b la ck
stage (T able VI).

The r e s u lts

C um berland v a r ie ty b e r r ie s
berries

of Logan v a r ie ty .

obtained s e e m e d

w ere m ore

to in d icate that the

r e s is t a n t to m old s

than the

T h e r e fo r e , it would s e e m that the Cum ­

berland v a r ie ty , o r any o th e r v a r ie ty w hich p r o v e s to be m ore

re­

sista n t to m o ld s, should be grown in a r e a s that have trouble w ith
m old count in b e r r i e s .

E ffe c t on the M old Count in B e r r ie s of Shaking the
B u sh e s B e fo r e H arv estin g

E x p erim en t 1 show ed that so ft b e r r ie s had the h ig h e st m old
count, and it w as

concluded that th ey m ight be the ca u se of the high

m old count in the c o m p o site sa m p le .
the s o ft b e r r ie s

The e a s i e s t w ay to e lim in a te

s e e m e d to be by shaking the b u sh es b efo re h a r v e stin g .

TABLE VI
AVERAGE MO liD OF LOGAN AND CUM BERLAND BLACK
RASPBERRIES IN DIF E'ER ENT STALES OF MATURITY
BEFO R E AND A F T E R SHAKING THE BUSHES
FOR H A R V E ST 1

S h in y -B la c k
V a r ie ty
3 e fo r e
Shaking

Lo^an

...................

C um berland

. .

Total m ea n s

...................

12.7

3.3

...................

12.0

6.0

...................

12.3

4.7

F V alue

T rea tm en t

. . .

V a r i e t y ...............

1

O rig in al data in Table XIV (Appendix).

* S ig n ifica n t.
* * H ig h ly sig n ific a n t.

A fter
Shaking

42
TABLE VI (Continued)

Dull -B la c k

lie f ore
Shakin*

A fte r
Shading

Soft

B e fo r e
Shaking

C om posite

A fter
Shaking

B efo re
Shaking

A fter
Shaking

39.7

10.0

87.0

59.3

79.7

41.0

24.0

10.7

67.7

40.0

5 3.3

31.3

31.8

10.3

77.3

49.7

66.5

36.2

39.33**

4 3 .5 5 * *

8 3 .4 8**

4.79*

2 1 .2 7 * *

2 9 .4 0 * *

43
S a m p le s that w ere h a r v e ste d b efo re

shaking the b u sh es had

an a v e ra g e of 12.3 p e r c e n t m old fo r the sh in y -b la c k b e r r ie s ,
per c en t fo r the d u ll-b la c l: b e r r ie s ,

7 7 .3 p e r cen t fo r the so ft b e r ­

r ie s , and 66.5 p e r c e n t fo r the c o m p o site
the b u sh e s , the b e r r ie s

s a m p le s .

VI) .

4 9 .’7 p e r cent; and the c o m p o site
The d e c r e a s e

A fter ‘shaking

in the sh in y -b la c k sta ge had an av era ge of

4.7 p er c en t m old count; the d u ll-b la c k s ta g e ,
sta g e ,

31.fi

10.3 p e r cent; the so ft

s a m p le s ,

in num ber cf m olds w as

sh in y -b la c k , 67.7 p e r c e n t fo r the d u ll-b la c k ,

36.2 p er cen t (Table

6 2 .2 p er cen t fo r the
35.8 p e r c e n t fo r the

so ft—
r ip e , and 4 3 .6 p e r ce n t fo r the c o m p o site sa m p le s

(Table VII).

Shaking the b u sh es b e fo r e h a r v e s t sig n ific a n tly d e c r e a s e d the
m old counts In b e r r ie s
cent d e c r e a s e s

at a ll s ta g e s

and E ise n b e r g

The g r e a te r p e r

in the s h in y -b la c k and dull s ta g e s w ere due to lo w e r

in itia l m old counts of the b e r r ie s
T h ese

of m atu rity.

(F ig u re

3).

r e s u lt s a r e in a g r e e m e n t w ith the sta tem en t of H e ls e l
(13), that:

S e v e r a l in s ta n c e s w e r e re p o rted in w hich g r o w e rs rem o v ed
o v e r r ip e b e r r ie s by shaking the b u sh es b e fo r e beginning to p ick
the cr o p .
This w as sa id to have r e s u lte d in th e ir picking on ly
sound b e r r ie s fo r the packing p la n ts.
T here w as oth er ev id e n c e
to in d ica te that s o m e g r o w e r s w ere aw are of the m oldy condition
o f so m e o f th e ir b e r r ie s and that th ey w ere in te r e s te d in d e liv ­
e r in g o n ly sound fr u it to p a c k e r s.

44
TABLE VE
REDUCTION IN MOLD COUNT OF LOGAN AND CUMBERLAND
3 LACK RASPBERRIES OF D IFFE R E N T STAGES OF
MATURITY A FT E R SHAKING THE BUSHES
S h in yB lack
<%)

D u llB lack
<%)

S o ftRipe
(%)

C om ­
p o site
(%)

.............................................................

73.6

74.8

31.8

48._

C u m b e r la n d ..............................................

50.0

61.1

40.9

41.3

C om bined (both v a r ie t ie s )

6 2 .2

67.5

35.8

45.6

V a r ie ty

Logan

. . .

E ffe c t on the M old Count of Holding D ry and Wet
B la c k R a s p b e r r ie s A fte r H a rv estin g

The tim e that e la p s e s b etw een h a r v e stin g and p r o c e s s in g has
been found to have a g r e a t e f f e c t on the m old count of the fin a l p r o d ­
uct ^8 ).

D ata obtained show ed that when b e r r ie s w ere h a r v e ste d and

p r o c e s s e d im m e d ia te ly , th ey had an a v e ra g e m old count of 45.2 p e r
cent; when h eld f o r s ix h ou rs b efo re p r o c e s s in g , the m old count in ­
c r e a s e d to an a v e r a g e of 60 p e r cent; and when h eld fo r tw elve
h o u rs, it in c r e a s e d to 77.2 p e r c e n t.
to be sig n ific a n t (T able VIII).

T h ese in c r e a s e s w e r e found

A high c o r r e la tio n w as found to e x is t

betw een the holding tim e and the n u m b er of m old s in b e r r ie s (F igu re

H tsto g ra n /
100- \

oI

th e

fie ld

b efo re- a n d a f t e r

C o u nt

o f

B e rri& s

H a r v e s te d

S h a k in g th e G u s h e s

Belot- Shakhg

SO -

lh& b u s h e s

£

30-

A
/Ifter Shaking
the Bus he S

o
10 _

"N

5
CO

*

k
*
CJ

-0

*
u

c

■v

50 -

&
-4

|
A
»x
X
X
*
<4

§>
G
>
'n?

O

W -

30 _

V

•x
%

ZD -

10

-

Z1

TA

$ hi ncj 6fade

A
D un B lo c h

Soft

i

£

,---------------

C o m p o site
Oi

46
TABLE VIII
MOiiD COUNT OF DRY AND WET BLACK RASPBERRIES FROZEN
IMMEDIATELY A FT E R HARVEST, AND FROZEN AFTER
HOLDING FOR SIX AND TWELVE HOURS
AT 76° TO 7 8 ° F . 1
Holding

T im e (hours)
A
o

0

Mold
Count
Avg.
P e t.

12

D ry

Wet

D ry

Wet

D ry

Wet

4. .0

45.3

61.2

5 8 .8

74.3

79.8

No.
of
Sam ­
p le s

72

Sam ­
ple
F
Value

Tj. S . D.
5%

1%

6.2 1** 17.40 23.10

* O rig in a l data in T a b les XV and XVI (Appendix).
* * H ig h ly sig n ific a n t.

4).

No sig n ific a n t d iffe r e n c e w a s found betw een holding the w et and

dry b e r r ie s

(T able VIII and F ig u r e 4).

The a v era g e m old count for

b e r r ie s that w e r e p r o c e s s e d im m e d ia te ly a fte r h a r v e stin g w as 45.0
p er cen t f o r the dry b e r r ie s and 45.3 p e r cen t fo r the w et b e r r ie s .
B e r r ie s

that w e r e h eld f o r s ix hou rs had an a v er a g e m old count of

61.2 p e r c e n t fo r the d ry b e r r ie s and 58.8 p e r cen t fo r the w et
b e r r ie s , and th o se h eld fo r tw elv e hours con tain ed an a v era g e of

<4.3

p er cen t m old count fo r the d ry b e r r ie s and 7 9 . 8 fo r the w et b e r r ie s .

47

(Qv t -

Ft g u t s <1

Ftooft - s s / o / < o f A1c IcJ c c >.. / */ o i
U )vt a n d D u / B etriz-z

O n H o l d i n g T im s .

u)*

HO

-

30

t z

rJotdincf Th u g Jh Hour'S

^0>

48
The la c k o f s ig n ific a n t d ifferen ce:: b etw een the h eld w et and
dry b e r r ie s
p le s .

m a y h a /e

b een due to the u se of in d ivid u al quart s a m ­

It m igh t be e x p e c te d that in la r g e

s ta c k s

of c r a t e s ,

w here the

ev a p o ra tio n w ould be d e c r e a s e d , the m old count of w et b e r r ie s w ould
in c r e a s e

at a m o r e

The r e s u lt s

rap id

rate than that of the d ry b e r r ie s .

o b ta in ed fo r holdin g a r e in g e n e r a l a g r e e m e n t

with th o se of F a b ia n e t a l . ( 8 ), who found that the m old count doubled
when b la c k r a s p b e r r ie s

w e r e h e ld fo r 8 - 1 / 4 hou rs under w a rm , hum id

c o n d itio n s, and in c r e a s e d fro m

2 to

e ig h t to th ir ty h o u r s.

and W ilco x (29), w orking on s tr a w ­

S te v e n s

b e r r i e s , sta te d that on ce
of e x te r n a l d ry in g is

the fungus

m ents

is

tim e s w hen sto r e d fo r tw enty -

in sid e the b e r r y no am ount

s u ffic ie n t to stop its

of the op inion that the m o is tu r e
the fungus

i

d e v elo p m en t.

in s id e the fr u it w as enough to a llo w

to g r o w s u f f ic ie n tly to d e s tr o y the b e r r y .

in d ic a te d that the

They w ere

T h eir e x p e r i­

rate of g ro w th of R hizopus n ig r ic a n s

v e r y ra p id ly w ith the in c r e a s e

o f te m p e r a tu r e above

10°

in c r e a s e s

C. (50° F .),

and w hen co n ta m in a te d b e r r ie s w e r e h e ld fo r a fe w h ou rs at a r e la ­
tiv e ly h ig h te m p e r a tu r e
t is s u e s

( i .e ., a t 30°

C .), the fungus d e v e lo p e d in the

to su c h an e x te n t as to c a u se the breakdow n of the b e r r ie s .
D ata o b tain ed a r e not in a g r e e m e n t w ith the

r e s u lt s obtained

by S te v e n s and W ilc o x (2 9 ), who s ta te d that the h ig h e r sh ip p in g

49

q uality of s tr a w b e r r ie s packed w et s e e m e d to be due to the la c t that
the tem p era tu re of the fr u it w as lo w e r ed by w ashing in cold w a ter,
and that by ev a p o ra tio n the b e r r ie s w e r e kept co o l fo r a c o n s id e r ­
able tim e .

They a ls o found that the drying of w ashed b e r r ie s , e s ­

p e c ia lly by e x p o su re to su n ligh t, in c r e a s e d d e c a y ca u sed by Rhi '.opus
sp ., a s the su b seq u en t e x p o su re o f the dry b e r r ie s

to p r e v a ilin g high

te m p e ra tu re s fa v o re d d evelo p m en t of the fungus w ithin the t is s u e s .

E ffe c t of W ashing T reatm en t on the
M old Count in 3 e r r i e s

It is

a w ell-k n o w n fa c t that w ashing the product is n e c e s s a r y ,

not o n ly fo r the r e m o v a l of d irt, but a ls o fo r the red u ction in the
num ber of m ic r o o r g a n is m s , and thus a product w ith lo w e r m old count
is obtained.

The b e tte r and m ore thorough the m ethod of w ash in g, the

fe w e r the num ber of o r g a n ism s that w ill rem ain on the product.

In

c o m m e r c ia l p r a c tic e th e r e a re s e v e r a l m ethods in w hich d ifferen t
p r in c ip le s a r e u sed f o r the re m o v a l o f d ir t and m ic r o o r g a n is m s .
Soaking in w a ter, trea tin g the p rod u ct in a s h a k e r -s p r a y w a sh er and
using h ig h -p r e s s u r e

sp r in k le r s a r e am ong the m ethods em p loyed .

One o f th e se m eth od s m igh t be e ffe c tiv e in one o r m ore of the p rod ­
ucts but l e s s

e ffe c tiv e o r un su itab le fo r o th e r s.

E ach p r o c e s s o r

u se s the m ethod w hich p r o v e s to give the b e s t r e s u lts under h is

50
c o n d itio n s .

In th is e x p e r im e n t, so m e of the m ethods w ere u se d and

the r e s u lt s ob tain ed w e re

co m p a red .

T hree lo t s o f b e r r ie s
to the w a sh in g t r e a tm e n ts .

of d iffe r e n t m o ld counts w e r e su b jected
The f i r s t lo t had an a v e ra g e m old count

of 37.0 p e r cent; the se c o n d lo t,
76.5

5 5.5 p e r cent; and the third lo t,

p e r c e n t w hen w a sh ed in a sh a k e r w a sh e r b e fo r e p r o c e s s in g .

T hese

r e s u lt s w e r e c o n s id e r e d as c o n tr o ls w ith w hich the r e s u lts

of o th e r tr e a tm e n ts w e r e c o m p a r ed .
When the b e r r ie s w e r e w a sh e d b y a s p r a y w a sh e r , the m o ld
count w as

r e d u c e d to 33.5, 4 8 .5 , and 71.0 p e r c en t fo r the f i r s t ,

seco n d , and th ird lo t s ,

r e s p e c t iv e ly (T able IX).

The m o ld count in be r id e s w ash ed in the sh a k e r w a sh e r , f o l ­
low ed by a sink, w a s h e r , had an a v e r a g e m old count o f 3 1.0, 4 4 .0 ,
and 55.0 p e r c e n t f o r the f i r s t , se c o n d , and th ird lo t s ,
B e r r ie s

r e s p e c tiv e ly .

w a sh ed b y th is m eth od had lo w e r m old counts than th o se

w ash ed in the s h a k e r w a s h e r a lo n e , or th o se w ash ed in a sh ak er
w a sh e r and then s p r a y -w a s h e d .
When the b e r r ie s

w e r e w a sh ed in a sh a k e r w a sh e r , then in a

sp r a y w a sh e r , and fin a lly in a sin k w a sh e r , th ey had a m old count
o f 2 7 .0 , 4 1 .0 , and 45.5 p e r ce n t, r e s p e c t iv e ly .

rl
TABLE IX
E F F E C T OF WASHING OH MOLD COUNT
OF BLACK R A SP B E R R IE S 1
Shake r
Shake r W ashed,
Sp ray
W ashed
and
W ashed,
Sink
and
Sink
W ashed
C
W ashed
D

Shake r
W ashed
A

Shake r
W ashed
and
S p ra y
W ashed
T*

{%)

<;%)

K%)

(%)

I

37.0

33.5

31.0

27.0

II

55.5

48.5

44.0

HI

76.5

71.0

C om bined

5 6 .3

51.0

T rea tm en ts

A vg. of lots.

F
V alue

i_. S . D.
5%

1%

2 3 .4 4 * *

2 .2 8

3.27

41.0

1 6 .4 4 * *

4.97

7.13

55.5

45.5

2 5 6 .3 7 * *

3.56

4 .0 8

43.5

37.8

1 0 3 .9 8 * *

2.30

3.15

O r ig in a l data in T able XVII (A ppendix).
* * H igh ly s ig n ific a n t.

The d a ta ob tain ed sh ow ed that the g r e a t e s t red u ctio n o f m old
count o c c u r r e d in b e r r ie s
(Lot III).

w h ich had the h ig h e s t in itia l m o ld count

S in c e the s o ft b e r r ie s

s e e m e d to be the c a u se fo r a high

m old count in a c o m p o s ite s a m p le , it m igh t be e x p e c te d that any
tr e a tm e n t b rin g in g about th e ir r e m o v a l, su ch as a h ig h w a te r -p r e s su r e

52

w ash, would r e s u lt in a lo w e r m o ld co\int fo r the rem a in in g in ta c t
fir m

b e r r ie s .

T h is m ay ex p la in the g r e a te r red u ction in m o ld count

when b e r r ie s having a

it • m old count a r e w ashed.

The a n a ly s is of v a r ia n c e of L ot II in d ica ted
d iffe r e n c e s

b etw een

lot in d ic a te d

T r e a tm e n ts

that i t

m ade

no

B

and

C,

d iffe r e n c e

and

in

no

C and

m old

sig n ific a n t
D t*

T his

count w hether

the b e r r ie s w e r e sp r a y ed ^r sin k -w a sh e d a fter s h a k e r -w a s h in g , and
that b e r r ie s

su b je c te d to s h a k e r -

m old count a s th o se
c o n s e c u tiv e ly .
w ashing i s

su b jected to s h a k e r -,

s in k -, and sp r a y -w a sh in g

F r o m th is data alo n e it m ig h t be in fe r r e d that sp r a y -

of no a d d itio n a l valu e in the red u ctio n of m old count

w h ere sin k -w a sh in g i s
r ie s ,

and sin k -w a sh in g had a s im ila r

p r a c tic e d , and that, with sh a k e r -w a sh e d b e r ­

sin k -w a sh in g c o n tr ib u te s no m o r e to the m o ld count red u ction

than sp r a y -w a s h in g .
The a n a ly s is of v a r ia n c e of L o ts I and III in d ica ted that a ll
tr e a m tm e n ts d iffe r e d w ith r e s p e c t to th e ir in flu e n c e on the m old
count.

In c o n tr a s t to L o t II, s ig n ific a n t d if f e r e n c e s w e r e found

^ A
B
C
D

-

S hak er w a sh e r
S h ak er w a s h e r
S hak er w a s h e r
S hak er w a s h e r
tr e a tm e n ts.

tr e a tm e n t.
tr e a tm e n t and sp r a y w a sh e r tre a tm en t.
tr e a tm e n t and sink w ashing tre a tm e n t.
tr e a tm e n t and sp ra y and sin k w ashing

53
betw een tr e a tm e n ts B and C, and C and 13.
sink - w ash in g w a s m o r e
bin ation of s h a k e r - ,

T h e se data show ed that

e f fe c tiv e than s p r a y -w a sh in g and that the c o m ­

s in k - , and s p r a y -w a s h in g w as m o r e e ffe c tiv e

that’ s h a k e r - and sin k -w a s h in g .
When a ll th r e e lo t s w e r e co m b in ed , it w as found that the ad­
d itio n a l w a sh in g tr e a tm e n ts r e s u lte d in the red u ctio n of m old cou n ts.
The c o n s is t e n c y

of the tr e a tm e n t e f f e c t s fr o m r e p lic a tio n to r e p li­

cation and lo t to lo t, p a r tic u la r ly w hen the r e p lic a tio n and lot
m e a n s v a r ie d , e m p h a s iz e d the valxie of the tr e a tm e n ts o v e r a ra th er
w ide ra n g e of in it ia l m o ld co u n ts.
In g e n e r a l,

th e s e

r e s u lt s w ould in d ic a te fo r the r e d u ctio n of

m old count in b la ck r a s p b e r r ie s that sp r a y -w a s liin g a fte r sh a k e r w ashing i s n ot g r e a tly e f f e c t iv e , and that fo r e f fe c tiv e
m old count the b e r r ie s
(F ig u r e

red u ctio n in

sh o u ld be sin k -w a s h e d w ith high p r e s s u r e

5).
h o t III, in w h ich the g r e a t e s t in it ia l m old count and the h ig h e st

red u ctio n w as ob tain ed , had a s t e e p e r slo p e than the o th er two cxirves
(F ig u r e

5)
A fe w w o r k e r s c a r r ie d out s im ila r e x p e r im e n ts .

F abian e t a l .

( 8 ) sta te d that b e r r ie s w a sh ed u n d er p r e s s u r e did not show a s ig n i­
fic a n t r e d u c tio n In m o ld count.

T h e s e r e s u lt s do not a g r e e with the

Fiyure 5
E f f e c t o { LOo s h i n y

T r e a + n j e - n t airi t h e M o / d C o u n i - i n B e r r i e s

80

C/Otinpf
Shake*

C o u n t

Washed

S h a K e t'
$ SprQij

Washed

SO

M o/d

40

ZO

Loti

I
A.'

Lot H

Lot HI

frio ld

e

u>
o

o

C o a a t

8

%

c\
$

s

C
E

C
3Q

r»

pa
0
rs

Jft

§

ft

MI £*
f t

S f t '*

V-

-

o,

ft

(V
a

v j?

(V ^
Ri c, ft

^
*
A
*v

f t

«

$

*

'-

i
Oi

i2 $
ft<iv ft
v

r^
O

ft

n.

^

r*k &
\

ft

•s.

*V

^

'S

S
£
V ift
-t '•
V
^' &
v *
fc

s

?

<t
ft

*k

N

<\

v 'r»
S
Ok - 5S .

ft
{?

'Is

V

ft
■s
%

0
5

ft
V

Ui
ui

56
data ob tain ed by the a u th or.
w hich 1 ablan and h is

It m ig h t be p o s s ib le

that the sa m p le s

c o - w o r k e r s u se d had a v e r y lo w in itia l m old

count w hen c o m p a r e d to that of the b e r r ie s u se d by the author.
The data ob tain ed during th is w ork a r e In g e n e r a l

agreem ent

w ith th o se of H a y n es e t a l . (12), who found 54 p er c e n t red u ction In
m o ld count o f s t r a w b e r r ie s when th ey w e r e w ash ed w ith S a n to m e r se
in a so a k e r w a s h e r , fo llo w e d by r in sin g w ith w a te r In a s h a k e r -s p r a y
w a sh e r .

They did n ot find c o n s is t e n t re d u ctio n of m o ld count e ith e r

w ith or w ithout a d e te r g e n t when the b e r r ie s w e r e
sta tio n a r y

s c r e e n , w h ich m a y be c o n s id e r e d

sp ra y ed on a

co m p a ra b le to the a ctio n

of the c o n v e y e r - b e lt - s p r a y w a s h e r u se d in th is w ork.

F u r th e r , they

noted 51 per c e n t m o ld -c o u n t d e c r e a s e when the b e r r ie s w e r e tr e a te d
w ith S a n to m e r s e un d er f o r c e d im m e r s io n w a sh e r ,

co m p a ra b le to sin k -

w ash in g p r o c e d u r e in th is w ork.

E ffe c t of

C o m p a r iso

h lu tior s oi M old Count of ^ilack
R a sp b e r r y P u lp

of o f f ic ia l m e t .od with m o d ifie d tech n iq u e fo r

m e a s u r in g m o ld count in b la ck r a s p b e r r i e s .

The m o ld count a s

o r ig in a lly d e v is e d by H ow ard (14) w as in ten d ed to count the num ber
of f ie ld s

co n ta in in g hyphae in tom ato p r o d u c ts, and the sa m e m ethod

57

w as la te r adopted to d e te r m in e the n u m b er of f ie ld s

containing hyphae

in b e r r ie s and b e r r y p r o d u c ts.
i o r d e te r m in in g m old count m o r e a c c u r a te ly in black r a s p ­
b e r r ie s , I l e l s e l and E is e n b e r g
in wM cl

p e ctin

(13) s u g g e s te d the m o d ifie d technique

so lu tio n w a s added to b e r r y pulp in a ra tio of 2 : 1 ,

in s te a d of eq u a l p a r ts by w e ig h t em p lo y ed in the m o d ifie d H oward
m ethod.

T h is p r o c e d u r e w as adopted during the c o u r s e of th is work

to d e te r m in e the m o ld count o f b la c k r a s p b e r r ie s .
A c o m p a r is o n of m o ld counts by both of the a u o v e -m e n tio n e d
m eth o d s w a s m a d e to d e te r m in e w h eth er th e r e w er e any sig n ific a n t
d if f e r e n c e s .
w ith m old

S e v e n ty -fiv e

r e p r e s e n ta tiv e

cou n ts ran gin g fr o m

s a m p le s of b la ck r a s p b e r r ie s

6 to 1 0 0 p er cen t w e r e exam in ed fo r

the c o m p a r iso n .
The e x p e r im e n ta l r e s u l t s

show ed a lin e a r r e la tio n sh ip b e ­

tw een the m o ld count and the d ilu tio n l e v e l s

(F ig u r e

7).

A n a ly s is of v a r ia n c e in d ic a te d h igh ly s ig n ific a n t d iffe r e n c e s b e ­
tw een m o ld cou n ts a t the l e v e l s ra n g in g fr o m 30 to 70 per cen t, and
s ig n ific a n t d if f e r e n c e s at the 20 to 30 and 80 to 90 p er cen t le v e ls .
No s ig n ific a n t d if f e r e n c e s w e r e obtained b etw een m o ld counts of tne

6 to 2 0 , 70 to 80, and 9 0 to 1 0 0 p e r c e n t le v e ls and when the a v e r a g e
of a ll l e v e ls
(T ab le X ).

w as c o m p a r e d , ■.o s ig if ic a r t d iffe r e n c e s w er e found

F t Cj I t i

58

Y

c

too
u t A Jo Jet Cottt/J~

/lc

a t,

L < = (Z ejd

A i o / d

70

O

t t

Mold

C o t/a t

tf -

ij

/

a

I At

d

h o d

Z . O Z -h /O . 3

X

/
so
Al o d i f / e d
^

4C

t/=

30

ZG

-

to

-

Lc3 iy ^

/ d

T e c ht* tq«CL

-3 .3 3 + 7 0 .3 S

X

59
TABLE X
ANALYSIS OF VARIANCE OF MOLD COUNTS ESTIM ATED BY
O FFIC IA L METHOD AND MODIFIED TECHNIQUE FOR
MEASURING MOLD IN BLACK R A SPB E R R IE S 1
Ave rage M old Count
L evel

M old
Count
(%)

O ffic ia l
M ethod

M odified
T echnique

1:1

2:1

(%)

(%>

F Value

1

6-20

11.0

8.0

3.24"

2

2 0 -3 0

22.5

18.5

6 .4 0 *

3

3 0 -4 0

34.0

29.1

1 0 .4 4**

4

40- - 0

4 4 .6

33.7

3 8 .3 4 * *

5

5 0 -6 0

53.5

46.5

1 8 .54* *

5

6 0 -7 0

64.9

5 7.1

1 5 .1 9 * *

7

7 0 -8 0

7 3 .6

71.4

2.03"

8

80-90

85.0

80.0

6 .7 3 *

9

90-100

9 3 .8

90.0

2.27"

54.34

49.25

1. 2 6 "

6-100

O rig in a l data in Table XVIII (A ppendix).
* S ig n ific a n t.
* * H ig h ly s ig n ific a n t.
Not s ig n ific a n t.

60
T h e s e r e s u lt s a r e In a g r e e m e n t with the o b se r v a tio n of H e ls e l
and E ise n b e r ^

(13) that m o ld cou n ts by e ith e r m eth od w e r e about the

sa m e fo r any p a r tic u la r sa m p le of b e r r ie s .

E ffe c t of adding d iffe r e n t am ou n ts of p ectin so lu tio n to olack
r a s p b e r r y pulp on m o ld co u n t.

A fte r com p arin g the o f f ic ia l m ethod

with m o d ifie d tech n iq u e s u g g e s te d by H e ls e l and E ise n b e r g

’13) fo r

m e a s u r in g m o ld count in b la ck r a s p b e r r ie s , a study w as m ad e to
d e te r m in e the e f f e c t of d llu tf ig bla ck r a sp b e r r y pulp with g r e a te r
am o u n ts of p e c tin

so lu tio n .

-dilution c u r v e s w e r e d e te r m in e d fo r m old counts ranging fr o m

20 to 1 0 0 p e r c e n t in b la c k r a s p b e r r ie s , by d ilu tin g the m ix tu r e of
pulp and p e c tin s o lu tio n w ith a d d itio n a l am ou n ts of the la tte r .
a d d itio n s of p ec tin so lu tio n to b e r r y pulp w ere m ad e
p rop ortio n of p e c tin to pulp w a s

7 .7 , and 6 . 6 , r e s p e c t iv e ly

so that the

1 : 1 , 2 : 1 , 6 : 1 , 8 : 1 , 1 0 : 1 , 1 2 : 1 , and

14:1, in w h ich the p e r c e n ts of pulp w e r e
9.1

The

50 .0 , 3 3 .0 , 2 0 .0 ,

14.3,

11.1,

(T able XI).

The r e s u lt s ob tain ed show ed h ig h ly s ig n ific a n t c o r r e la tio n
r a tio s b e tw e e n m o ld cou n ts and d ilu tio n s (i ig u r e 8 ).

The red u ction

in m o ld count o f b e r r ie s w a s not in d ir e c t p rop ortion to the dilution
of the sa m p le w ith p e c tin so lu tio n .

61
TABLE XI
E F F E C T OF ADDING D IF F E R E N T AMOUNTS OF PE C T IN
SOLUTION TO BLACK R A SP3E R R Y P U L P
ON MOLD C O U N T 1
(a v e r a g e m old count in v a r io u s d ilu tion s)
D ilu ­
tion
(p e c ­
tin
to
pulp)

P e t.
of
Pulp
in
Sam p ie

Le v e ls

20-

of M old Count

4050

50-

60-

30

3040

60

8090

90-

70

7080

100

1:1

L0

2 2 .9

34.0

4 4 .6

5 3.5

64.9

7 3.8

85.0

9 4.7

2 :1

33.3

19.1

29.1

34.3

47 .3

58.0

70.9

80.0

91.1

4:1

20.0

1 6 .0

2b. 3

2 9 .4

41 .3

5 2 .6

63.1

72.5

8 6 .0

6:1

14.3

12.9

22.0

2 5 .7

37.0

49-7

56.2

67.5

78.9

8:1

11. 1

11.3

18.0

2 4 .3

33.3

4 4 .3

50.7

5 9-5

72.7

10:1

9.1

8.3

15.4

21 .7

29.3

39.1

4 3 .8

55.5

6 5 .8

12:1

7.7

6.0

13.7

18.9

2 7 .3

35.4

38.2

49-5

54.9

14: 1

6.6

3.7

10.3

14.9

23.0

33.1

34.9

43.5

46.7

1 O rig in a l data in Table XIX (A ppendix).

Mo i d Coat i t
n
*

os~ ok

C>

"K
£ ’£ *

-V .

V

''t-

Q

V
<v
>

•s

a '/z jy

s.
V

£

'//

£

»v
N

•s.

\

"♦k

it

OVZ

OD

&
f\

V
V. '
V.

s.

9 - j f e V s '/'/ /'£ * /

S fd u 4 o g

ft
V

>1

>
fc>
"V

i)
a
Ci
*
r-

T h e se r e s u l t s a r e in g e n e r a l a g r e e m e n t w ith th ose obtained
S tein k ra u s

(2b).

DISC USSIO N

Fx^ e r im e

:ai r e s :lts i :d’ c it e d a c lo s e

c o r r e la tio n b etw een

sta g e of m a tu rity and m old count of black ra spbc r r i c s .
r e c o g n is e d that s o ft fr u its a r e m o r e

It has been

s u s c e p tib le to attack by fungi

and o th er m ic r o o r g a n is m s , and the e x p e r im e n ta l w ork d em o n str a ted
that b e r r ie s in ad van ced s t a g e s of m atu rity
m old count than th o se in e a r l i e r
d itio n s.

T h is m ay

by wind or ra in
d is s o lv in g

alw

.s

and

r

h ig h er

rip en in g s ta g e s under s im ila r c o n ­

be due to m e c h a n ic a l injury

of the sk in ca u sed

w hile the b e r r ie s w e r e on the b u sh e s , or by the

of the sk in b etw een in d iv id u a l d r u p e le ts by m old e n z y m e s ,

p erm ittin g the m o ld s to e n te r the fr u it.

The p r e s e n c e of su g a r

and

a c id s in the fr u its fa v o r s rap id d e v e lo p m e n t of m o ld s a fte r they
once e n te r the b e r r ie s un d er p ro p er e n v ir o n m e n ta l c o n d itio n s.
c lo s e

A

c o r r e la tio n a ls o e x is t e d b etw een the m old cou n ts in so ft b e r ­

r ie s and of c o m p o s ite

s a m p le s w hich w e r e a m ix tu r e of s o ft fr u it

having a high m o ld count, w ith d u ll or sh in y -b la c k r a s p b e r r ie s
having lo w e r m o ld c o u n ts.

The b e r r y m a tu rity and the tim e in t e r ­

v a l b etw een r ip en in g and h a r v e stin g of the b e r r ie s fo r d e liv e r y to
the fa c to r y

s e e m e d to be d om in an t fa c to r s in flu en cin g the m old

count of b la ck r a s p b e r r ie s .
64

T h e r e w ns no doubt that w ea th er co n d ition s during the h a r ­
v e stin g p e r io d of b la c k r a s p b e r r ie s a ffe c te d the co n d itio n s of the
fr u it.

The e x p e r im e n ta l r e s u lt s in d ic a te d a d e fin ite trend tow ard s

h igh er m o ld co u n ts w ith a d ela y of h a r v e s t fo llo w in g a ra in .

i t wJ'S

o b se r v e d that the f a r m e r s w aited too long a fter a ruin to pick the
b e r r ie s , a ffo rd in g an opportxmity fo r the m o ld s to d ev elo p .
p ic k e r s

The

w e r e found to le a v e fo lia g e -h id d e n fr u its u n h a rv ested ,

w hich then b e c a m e o v e r r ip e , in fe c te d , and se r v e d a s a so u r c e of
fu rth er in fe c tio n .
the b e r r i e s .

It w a s • noted that ra in h asten ed the m atu rity of

H eavy ra in not only m a d e the fr u it so fte n m o r e

q u ick ly, but s o m e t im e s b r u is e d the b e r r ie s , w hich then b ec a m e m o r e
s u s c e p tib le to a tta c k by m o ld s .
July 21.

In 1951, th ere w as a heavy r a in on

A fte r two d a y s, a s lig h t fungus grow th w as o b se r v e d on

b r u ise d d r u p e le ts n e a r the c a p s of m o s t sh in y -b la c k b e r r ie s .

At

the sa m e tim e , b e r r ie s in m o r e ad van ced s ta g e s of m a tu rity had
p ro fu se e x te r n a l m y c e lia l grow th.
b e r r ie s did not sh ow any v is ib le

U ninjured, fir m

sy m p to m s of m o ld , though they w ere

am ong h e a v ily in fe c te d fr u it in the sa m e c lu s t e r s .
the f i r s t v is ib le

sh in y -b la c k r a s p ­

In m any c a s e s

sy m p to m s of m o ld attack e ith e r in the d u ll or

s h in y -b la c k s t a g e s o ften w e r e found to be on the d r u p e le ts n e a r the
p la c e w h e r e the fr u it i s

d eta ch ed fr o m the r e c e p ta c le .

T h is in d ic a te s

66
that the m old m ig h t h ave e n te r e d the b e r r y through the b a s a l portion
of the fr u it when i t w as lo o s e n e d fr o m the cap.

In dry w ea th er,

p r o fu se m y c e lia l grow th w as noted n ear the b a sa l p o rtion s of d u llb lack b e r r ie s ju s t m a tu rin g in to the so ft sta g e .
The data obtained show ed s ig n ific a n t in c r e a s e in m o ld count
of s o ft rip e and c o m p o s ite
h o u rs a fte r r a in .
c o n s id e r a b ly .

sa m p le of b e r r ie s w ithin tw en ty -fo u r

A fte r tw e n ty -fo u r h o u r s, the m o ld count in c r e a s e d

The g r e a t e s t change in the m old count of b e r r ie s w a s

noted in b la c k r a s p b e r r ie s that w e r e p icked fr o m b u sh es w hich had
not b een h a r v e s te d fo r fou r d a y s.

T h is undoubtedly w as due to the

d r o p p in g -o ff of m any of the o ld e r h e a v ily in fe c te d fr u it s , and the
fa c t that w e a th er c o n d itio n s w e r e u n favorab le fo r g e r m in a tio n and
grow th of m o ld s p o r e s .

O b se r v a tio n s m ad e at the f a c t o r ie s

show ed

that the m old count in the b la c k r a s p b e r r ie s w as low a t th e b e g in ­
ning of the s e a s o n , when the w ea th er w a s hot and dry, but m old
count in the b e r r i e s I n c r e a s e d la t e r in the s e a s o n , fo llo w in g r a in ­
f a ll.
T h e r e fo r e , i t w ould s e e m

to be e s s e n t ia l to d e v e lo p a s y s te m

of h a r v e stin g w hich would in s u r e the c o lle c tio n of b e r r ie s b e fo r e
they b e c o m e too m a tu r e .

A t t im e s , su ch a s y s te m m ay r e q u ir e the

h a r v e s tin g of be r id e s w hen they a r e w et fr o m dew o r r a in .

On the

b a s is

of the data obtained during the c o u r s e of th is in v e stig a tio n , it

i s ju s tifia b le to a s s u m e that the h a r v e stin g of black r a s p b e r r ie s
should be m ade w ithin tw e n ty -fo u r h o u rs aftex’ r a in fa ll.
F arm ers

have often x-eported that they had a m a jo r prob lem

in p rocu rin g h elp in h a r v e stin g berxd.es when they w ere w et, and as
a r e s u lt they w e r e

le ft xm narvested fo r so m e tim e .

Thus, m o ld s

would have a cn a n ce to a tta ck the fr u it during a wet p eriod and
would d e v elo p rap id ly in s id e the fr u it if the w eath er b eca m e hot
fo llo w in g the r a in .
B e s id e s h a r v e stin g the fr u it w ithin tw en ty -fo u r itours a fter
r a in fa ll, a n oth er m eth od could be em p lo y ed to r e m o v e so ft, o v e r r ip e
frxiits w ith high m o ld co u n ts.

F r o m the e x p e r im e n ta l r e s u lt s it was

found that shaking the b u s h e s of C um berland and L ogan v a r ie t ie s
b e fo r e h a r v e s t c a u se d a p p r e c ia b le red u ctio n in m old count.

To

m ake p r a c t ic a l u s e of th e s e fin d in g s , one m u s t e ith e r supply le a th e r
g lo v e s to p ic k e r s in o r d e r to obtain th e ir c o o p er a tio . in tne snaking
o p e r a tio n , or d e v is e a m e c h a n ic a l m e a n s of shaking the b u sh e s b e ­
fo r e h a r v e s t.

It i s

a co m m o n b e lie f of the g r o w e r s that the grow ing

of the L ogan v a r ie ty w ould a v o id high m old count, s in c e th is v a r ie ty
of b e r r ie s m a tu r e s e a r lie r than the C um berland v a r ie ty .

H o w ev er,

the fa c tu a l data do not su p p o rt th is v ie w , and the m old count of

68

b lack

r a sp b e r r ie s

the h a r v e s tin g

is

m o r e dependent on

w eather

conditions during

p erio d than on the v a r ie ty .

The t im e in t e r v a l betw een H arvesting the b e r r i e s and p r o ­
c e s s i n g th em i s

g e n e r a lly

r e c o g n iz e d by e v e r y o n e

co n c e rn ed with the

in d u stry a s an im p o r ta n t fa c t o r in in flu en cin g the m old count.

T u ere

was d efin ite e v id e n c e f r o m t h e s e e x p e r im e n ts that the m o ld co u rt
in c r e a s e d

as the tim e of holding the b e r r i e s

longed b e fo r e p r o c e s s i n g .
in the i n c r e a s e

at the fa c to ry

was p r o ­

The data show ed no sig n ific a n t d iffe r e n c e

of m o ld count b etw een dry and w et b e r r i e s when

they w e r e h e ld under id e n t ic a l c o n d itio n s.

When the m old w as p r e s ­

ent ir.side the b e r r i e s , i t s e e m e d to find a fa v o r a b le m e d iu m for
rapid d e v e lo p m e n t under p r o p e r e n v ir o n m e n ta l c o n d itio n s.

In a d d i­

tion, it was d iffic u lt to e s t im a t e the m o ld count in the b e r r i e s by
v is u a l a p p e a r a n c e of the fru it.
Whe n fr u it w a s r e c e i v e d a t the fa c to ry , i t w as found p o s s ib le
to red u ce the m o ld count by applying high w a ter p r e s s u r e during
p r o c e s s in g of the b e r r i e s .
w asher,

A com bination of tr e a tm e n t with sh ak er

w a te r sp r a y on the b e lt, and w ashing with w a ter in sin k by

thorough a g ita tio . s e e m e d to be the m o s t e f f e c t iv e m ethod fo r r e ­
ducing m o ld count in b e r r i e s under n o r m a l fa c to r y o p e r a tio n s .

When

Mg', w ater p r e s s u r e w a s u sed o i l y the f i r m b e r r i e s having lo w e r m old
cou n ts.

69
T lie m o Id -cou n t m etliod lias been u sed for m any v e a r s a s an
o b je c tiv e t e s t fo r d e te r m in g the r e la t iv e amoiuit of d e c o m p o sitio n in
f r u it p ro d u cts.
necessary

The m o ld - c o u n t p r o c e e d u r e i s a co n v en ien t and often

t e s t fo r p ro p er

canned r a s p b e r r i e s ,
f r u it i s

evalu ation of the quality of fr o z e;, or

b e c a u s e the o r ig i

\ l a p p eara n ce of the fres;_

s o a l t e r e d by the p r o c e s s in g a s to m ak e d ir e c t v is u a l e x a m i­

nation d iffic u lt and inadeq u ate.

F o r p ro p er evaluation of the m o ld

population i t i s n e c e s s a r y to p r e p a r e
c i l i t a t e s accxirate e x a m in a tio n .

the s a m p le s in a way that f a ­

The g r e a t e r dilution of two p a rts

p ectin so lu tio n to one part of pulp p r e p a red the sa m p le for e a s i e r
e x a m in a tio n than the o f f ic ia l m ethod now in g e n e r a l u s e .

T n is

change ir the m eth o d c a u se d a ligliening of the deep c o lo r and d e ­
c r e a s e d the d e n s ity of pulp taken f r o m f r o z e n r a s p b e r r i e s .
e x p e r im e n ta l r e s u l t s

The

show ed no s ig n if ic a n t d if f e r e n c e s in the o v e r ­

a ll m o ld count b e tw e e n the o f f ic ia l and m o d ifie d m e th o d s, with the
m o d ifie d m eth o d g e n e r a lly

show ing s lig h tly lo w e r m o ld co u n ts.

When

the m ix tu r e of r a s p b e r r y pulp and p e c tin so lu tio n w as diluted fu rth er,
i t w as noted that th e r e w as a p r o g r e s s i v e d e c r e a s e with dilution, but
the r ed u ctio n in m o ld count w a s not in proportion to the am ounts of
d ilu tion .

H ighly s ig n if ic a n t c o r r e la t io n r a t io s at a ll l e v e l s of dilutions

w e r e obtained, in d ic a tin g a n o n lin ea r r e la t io n s h ip b etw een m o ld count
in the b e r r i e s and d ilu tio n s of the s a m p le s .

SUMMARY AN

CONCLUSIONS

A study w as m a d e to d e te r m in e:
ra sp b e r r ie s

(1) the m o ld coim t of black

c o l l e c t e d at v a r io u s s t a g e s of m atu rity and at d iffe r en t

i n t e r v a l s a ft e r rain; (2) the e f f e c t of Holding dry and w et b e r r i e s ou
the m o ld count; (3) the e f f e c t of snaking the black r a s p b e r r y
b e fo r e liar e stin g ;

bu sh es

(4) the e f f e c t of d iffe r e n t m eth o d s of wasuin g on

the m old count; and (5) the r e la tio n s h ip o etw eeu v a r io u s dilution
m e th o d s and the m o ld count.
The data obtained during the

1951 and 1952 s e a s o n s

show ed

that:
1.

Soft, r ip e black r a s p b e r r i e s had h igh er m old coicnts tn.au

any o th er s ta g e of m a tu r ity , and e lim in a tin g th e s e f r u it s would
g r e a tly r e d u c e the m o ld count.
2.
count,

W eather co n d itio n s play

an im p o r ta n t part in the m old

and the f r u it should be h a r v e s t e d im m e d ia t e ly

a fte r a rain to

k eep the m o ld count a t a lo w e r l e v e l .
3.

The m o ld counts of the

s ig n if ic a n t ly lo w e r at a ll s t a g e s of
4.

C um berland black r a s p b e r r y w e r e
m a tu r ity than the L ogan v a r ie ty .

Shaking the b u s h e s b e fo r e h a r v e stin g s ig n ific a n tly red u ced

the m o ld count.
70

71

t.

Holding the b e r r i e s a fte r h a rv estin g caused highly s ig n if i­

cant i n c r e a s e s in the m old count, and the r e s u lts obtained indicated
that the fr u it shoxild be p r o c e s s e d
v.

l e s s than s i x hours afte r picking.

Washing s e e m e d to be e f f e c tiv e in reducing the m old

co u rt of b e r r i e s .

Sxibjecting b e r r i e s to w ater w ashing by shaker

w a s h e r , w a te r sp ra y on the c o n v e y e r belt, and sink washing with
t:.e rough agitation, of the fru it was found to be the m o s t e ffec tiv e
m ethod in reducing the m old count.
7.

No sig n ific a n t d if f e r e n c e s w e r e found between the o ffic ia l

and m o d ifie d m e th o d s of m old counting.
8.

Adding d iffe r en t am ounts of pectin solution to black r a s p ­

b erry pulp lo w e r e d the m o ld count, but it s d e c r e a s e was not in d i­
r e c t proportion to the am ounts of p ectin solution.

BIBLIOGRAPHY

B e r t a r e l l i , E ., rind M. M a r c h e lli.
B a c t e r i o lo g ic a l E xam ination
of T om ato P r o d u c t s
Ann. d'Igiene 3^, 3 0 9 -3 2 2 (1920).
B e n e k e , E . S.
The v o lu m e o c c u p ie d by fungus hyphae in r a s p ­
b e r r y f r u it s .
M ich. A g r . Exp. Sta. Q u a r te r ly B u lle tin .
3 3 , (2), 1 2 4 -1 2 6 (1950).
B ig e lo w , W. D.
R e p o r t on Canned V e g e ta b le s .
2 , 4 5 2 -4 8 5 (1920).

J. A. O. A. C.

C layton, C. N.
The G e r m in a tio n of Fungus S p o r e s in r e la tio n
to c o n tr o lle d h u m id ity .
P hytop ath ology.
32, 9 2 1 -9 4 3
(1942).
D a r r o w , S. M ., and G. F . Waldo.
R a sp b e r r y C ulture, U. S.
D ept, of A g r . F a r m e r s B u lle tin 8 8 7 , 3 1 -3 2 (1941).
D odge, B . O ., and R. B . W ilcox.
D i s e a s e s of R a s p b e r r ie s and
B la c k b e r r ie s.
U. S. D e p a r tm en t of A gr. F a r m e r s B u lletin
1488, p. 20, S e p te m b e r , 1941.
b u g g e r , B . N.
P h y s i o l o g i c a l S tu d ie s with R e f e r e n c e to the
G e r m in a tio n of C e r ta in F ungous S p o r e s .
B o ta n ic a l G a z e tte ,
31, 3 8 - 6 6 , 1901.
F ab ian , F . W., E . S. B e n e k e , F . J. E r ic k s o n , and R. F lo a t e .
What i s a R e a s o n a b le M old Count fo r B la c k R a s p b e r r ie s
in the G r e a t L a k e s R egion .
The Canner.
112 (18), 14-16;
(19). 1 6 -2 0 ; (20), 1 6 -2 0 (1951).
F e d e r a l S e c u r ity A g e n c y .
N o t i c e s of Judgem ent under F e d e r a l
F o o d , Drug, and C o s m e t ic A c t, M a y - D e c e m b e r , 1950, and
A p r il, 1951.
F e d e r a l D rug A d m in is tr a tio n .
M ic r o a n a ly s is of Food and Drug
p r o d u c ts .
U nited S ta te s G o v ern m en t printing o f f ic e , W ashin to n , 1 5 3 - 1 5 4 and 171 (1951).

73
11.

G a llo w a y , L». D.
M o is tu r e R e q u ir e m e n ts of Mold Fungi with
S p e c ia l R e f e r e n c e to M ild ew in T e x t il e s .
Journal of
T e x t ile In situ te .
2 6 , 123*129 (1935).

12.

H a y n e s , R. D .. J. O. H a r r ie t H a r lin , R. S. Mundt.
The u s e of
d e t e r g e n t s in r e m o v in g m o ld f r o m s t r a w b e r r i e s .
Quick
F rozen F oods.
1_5, 5 3 - 5 6 (1953).

13.

H e l s e l , W. G ., W. W. E is e n b e r g .
b e r r ie s.
M ich ig a n S u r v e y ,

D e c o m p o s itio n in B la c k R a s p ­
1950.
U npublished.

14.

H ow ard, B . J.
T o m a to Ketchup under the m i c r o s c o p e with
p r a c t i c a l s u g g e s t io n s to in s u r e a c le a n ly product.
United
S t a t e s D e p a r tm en t of A g r ic u lt u r e B u rea u of C h e m istr y
C ir c u la r . 6 8 , 1 - 1 4 (1911).

15.

H ow ard, B. J ., and S te p h e n so n .
M ic r o s c o p ic a l s tu d ie s on tom ato
p r o d u c ts.
U nited S ta te s D e p a r tm en t of A g r ic u ltu r e .
D e­
p a r tm e n t B u lle tin 581, 1 - 2 4 (1917).

16.

H o w a r d , B . J.. E f f e c t of the u s e of d iffe r e n t in s t r u m e n t s in
m aking a m i c r o s c o p i c a l e x a m in a tio n fo r m o ld in tom ato
p r o d u c ts .
J. A. O. A. C. 5, 2 2 6 -2 2 7 (1922).

17.

L a u r it z e n , J . I. The r e la tio n of
in f e c t io n by c e r t a in fungi.

18.

L illy ,

19.

L o r e e , R. E .
R a s p b e r r y G row ing in M ich ig a n , M ichigan State
C o lle g e , E x te n s io n B u lle t in 287 (1949).

20.

M i lle r , M. H a r r y .
M o d ific a tio n of the Howard M ethod fo r C ount­
in g Y e a s t s , S p o r e s and B a c t e r i a in T om ato P r o d u c t s .
Ind.
Eng. C hem .
_12, 7 6 6 -7 6 9 (1920).

21.

N a tio n a l C a n n e r s A s s o c i a t i o n .

22 .

N e e d h a m , G . H ., and C. K. F e l l e r s , A p p lica tio n o f Howard Method
to the D e te c tio n of S p o ila g e in B e r r y P r o d u c t s .
J . A. O. A.
C. 8 , 3 1 2 - 3 2 7 (1925).

te m p e r a tu r e
and hum idity to
P h y top a th olog y , 9, 7 -3 5 (1919).

V. G ., and H. G. B a r n e tt. P h y s io lo g y of the F u n gi.
M c­
G r a w - H ill B ook Com pany, In c ., N ew Y ork.
pp. 3 5 5 -3 9 5 (195!

Canned P a c k S t a t is t i c s (1950).

74
23.

O ffic ia l and T en ta tiv e M ethods of the A s s o c ia t io n of O ffic ia l
A g r ic u lt u r a l C h e m is t s .
7th edition (1950).

24.

P r e s c o t t , S. C ., S e v e r a n c e B u r r a g e , and B. G. P h ilb u ck .
Som e
S o u r c e s of E r r o r in the M ic r o s c o p ic a l E xam in ation of
C e r ta in Food P r o d u c t s .
Abs. of B a c t., 1_, 51 (1917).

25.

R e n d e li, T.
O b s e r v a t io n s on C hanges in R a s p b e r r ie s A fter
P ic k in g .
A n a ly st, 5<B, 73 (1933).

26.

S la te , G. L ., A. J. B raun, and F . G. M undinger.
R a sp b e r r y
G r o w in g - - C u lt u r e D i s e a s e s and I n s e c t s .
C o r n e ll E x te n sio n
B u lle tin .
719 (1947).

27.

Snow, D ., M. H. G. C richton, and N. C. Wright.
M old D e t e r i o r a ­
tion of F e e d in g Stuffs in R elation to Hunidity o f S to r a g e ,
P a r t I.
The Grow th of M olds at Low H u n id ities.
A nnals
of A pplied B io lo g y , 31, 1 0 2 -1 1 0 (1944).

28.

S te in k r a u s, K. H.
M e a s u r e m e n t of M old in R a s p b e r r ie s .
C an n er.
115 (21), 22 (1952).

The

29.

S t e v e n s , E ., and R. B. W ilco x.
R hizopus Rot of S t r a w b e r r ie s in
T r a n s it .
U. S. Dept. A g r ., B u lle tin 531 (1917).

30.

C teve.is, N. E .
Keeping Q uality of S t r a w b e r r ie s in R e la tio n to
T h e ir T e m p e r a tu r e when P ic k e d .
P h ytopathology, 9^ 171177 (1919).

31.

S te w a r t, J. A ., and B urton J. C lark .
Canned Food R e f e r e n c e
M anual, 3rd e d itio n .
A m e r ic a n Can Com pany, prin ted by
R o g e r s - K e l l o g g - S t i l l s o n , Inc. (1949).

32.

V in c ie n t.
The D i r e c t o r B r e e d Method fo r Counting B a c t e r i a
in T om ato C atsup, P u lp o r P a s t e .
Journ. of B a c t. _3,
1 8 3 -1 8 5 (1918).

33.

W alk er, J. C. P la n t P a th o lo g y .
C o., Inc. (1950).

P u b lis h e d by M c G r a w -H ill Book

A P P E N D IX

75

TABLE XII
MOLD COUNT ON F R U IT HARVESTED A T D IF F E R E N T HOURLY
INTERVALS A F T E R RAINS ( 1 9 i2 SEASON)
T.ours Af^.e r Rain
Sta^e: of
Matu rity

S h in y -b la c k

F ie ld
No.

. . .

. . . .

1 7 -1 8
(%)

2 3 -2 4
(%)

48
■.%)

Co)

72

1.

2

0

2

8

6

2.

0

2

0

0

12

3.

4

0

0

8

14

4.

0

2

0

10

16

14

16

20

20

14

6.

6

4

4

6

8

7.

0

4

8

10

12

8.

6

8

10

14

10

1.

8

8

8

12

24

2.

4

6

0

6

30

3.

8

0

6

8

14

4.

12

2

6

20

22

r
.' *
—

28

22

38

40

36

6.

8

0

14

12

18

7.

4

6

20

12

14

8.

10

12

16

18

22

*

D u ll-b la c !

i 3-14

77

TA3L.E XII (Continued)
Hours A fter Rain
S ta g e s of
M aturity

Soft

...........................

C o m p o site

. . . .

F ie ld
Ho.

13-14
(%)

1 7 -1 8
(%)

2 3 -2 4
(%)

48

72

(%)

<%>

1.

12

24

40

62

56

2.

72

72

22

24

42

3.

16

42

20

72

54

4.

14

12

18

40

42

f

28

62

90

46

68

6.

70

90

56

78

100

7.

46

6o

86

100

24

8.

28

38

46

66

88

1.

32

56

30

20

30

2.

22

20

12

40

52

3.

14

20

26

18

40

4.

10

24

32

30

28

5.

24

38

56

36

50

6.

52

62

84

52

62

7.

24

32

50

66

20

8.

16

20

32

46

52

78
TA3L.E XJH
E F F E C T OF HARVESTING 2L A C K RASPISERR J.ES AT D IFFER ENT
INTERVALS A F T E R RAIN ON JUDY 11 AND 12, 19:1
M old Count (pe r cent)
r n te r v a l

S in c e
P r e v io u s
H arvest

1 day

2 d ays .

F ie ld
No.

M aturity S ta g e s
S h in y llack

D u llN laek

SoftRipe

Cornp o site
S a n ip ie s

1.

4

18

74

22

2.

4

4

62

8

3.

4

12

100

20

4.

4

10

80

20

5.

2

12

76

20

6.

0

14

46

30

7.

8

10

70

26

8.

6

14

92

48

9.

4

12

64

24

10.

2

10

62

22

1.

0

2

50

14

2.

6

18

68

30

3.

8

20

80

26

4.

4

16

52

20

5.

6

20

46

24

6.

4

18

100

22

7.

4

4

72

8

8.

4

12

6o

20

9.

4

74

48

22

10.

8

62

42

30

:9
TACLE x n i

Interval
S in c e
P rev io u s
H arvest

3 days . .

F ie ld
No.

1 d ays . .

M old Count tper cent)
*---------------------------------- —-------------------------M aturity Stacie:
---------------------------------------— ■
—*—
S h in y D u llS o ftB la c k
31ack
Ripe
•

O

C om p o s ite
Sam p ies

1.

0

0

100

6

2.

8

40

100

76

3.

0

18

56

68

4.

8

20

90

54

*

16

26

94

62

1.

0

8

8

4

2.

4

4

12

6

3.

2

4

10

4

4.

2

12

10

4

r

4

6

6

6

l.

2

4

10

4

2.

4

8

16

12

3.

4

10

20

6

4.

6

18

24

10

5.

4

12

42

10

_

4 days . .

(Continued)

80
TABLE X iv
E F F E C T OF SHAKING BUSHES ON MO! D COUNT OF 3ER R IL S
Mold Count {per cent)

V a r ie t y

Lo^ran

. .

Cumbe r land . . .

F ie ld
No.

Shiny
B la c l ;

Dull B la ck

Soft

B e­
fore

A fte r

Be­
fo r e

A f­
te r

Be fo r e

1.

16

6

34

10

82

z.

14

4

40

12

3.

4

0

46

4.

20

4

5.

4

6.

Compo: ',ite
A fte r

B e­
fore

A f­
te r

60

90

50

76

54

84

40

8

88

60

76

38

52

14

94

62

82

40

0

28

4

92

6o

70

38

18

6

38

12

90

60

76

40

1.

2

6

20

8

86

56

60

40

2.

10

4

24

6

70

40

56

30

3.

16

8

44

16

68

38

62

34

4.

10

4

24

14

82

52

60

32

5.

20

8

12

12

54

28

40

26

6.

14

6

20

8

46

26

42

26

81
T A B L E XV
E F F E C T OF HOLDING W ET BERRIES FOR ZERO, SIX, AND
TWELVE HOURS AT 76° TO 78° F.

Date of C o lle c t io n

J u ly

18,

J u ly 23,

1 9 5 2 .......................

1 9 5 2 .......................

S a m p le
No.

Mold Count (p e r cent)
0 Hours

6 Hours

1.

78

74

100

2.

22

28

98

3.

56

72

94

4.

36

42

L2

5•

62

84

100

6.

42

66

82

1.

44

68

84

2.

10

16

24

3.

54 •

70

92

4.

42

60

78

n.

62

80

94

6.

36

46

60

12 Hours

82
TAI2L.ii: XVI
E F F E C T O F HOLDING DRY BLACK RASPBERRIES FOR ZERO,
SIX, AND TWELVE HOURS AT 7 6° TO 7 8° F .

D ate of C o lle c tio n

J u ly 17,

1 9 : 2 .......................

S am p le
No.

0 Hours

6 Hours

12 Hours

1.

32

76

86

2.

60

84

90

3.

72

40

56

4.

22

30

42

•

44

68

72

6.

30

56

66

1.

52

70

92

2.

64

80

96

3.

76

86

100

4.

32

54

68

5.

26

36

58

6.

30

54

66

—

J u ly 21,

1 9 - 2 .......................

Mold Count (per cent)

8 :>
TABLE XVII
E F F E C T OF WASHING WITH WATER ON MOLD COUNT
OF 3 ACK RASPBERRIES
Mold Count (per cent)

L ot

I

II

HI

S a m p le
No.

Shaker
Washed
and
SprayW ashed

Shaker
Washed
and
Sink
W ashed

Shake r
Washed,
Spray
W ashed,
and
Sink
Washed

a.

30

28

26

24

b.

42

38

36

32

c.

30

42

40

38

d.

26

26

22

22

a.

60

56

48

40

b.

44

32

32

34

c.

52

48

42

40

d.

66

58

54

50

a.

82

76

60

56

b.

74

70

56

44

c.

74

68

52

40

d.

76

70

54

42

84
T A 3L E X V i n
M EASUREM ENT OF MOLD IN 3 LACK R A SP3ER R IES ES TIMA TEE
3 Y ORIGINAL HOWARD METHOD AND MODIFIED TECHNIQUE
Mold Count (%)
O fficial
Me thod
a

M odified
Method

Mold Count (%)
O fficia l
Method

M odified
Method

Mold Count (%)
O fficia l
Me tho d

M odified
Method

6
6
10
10

6
4
6
8
6

40
42
42
46
46

32
38
28
32
36

72
74
74
74
76

70
64
72
76
74

12
12
14
16
18

8
10
6
12
14

48
48
50
50
32

34
36
42
46
46

76
78
82
82
84

76
76
74
76
76

20
20
20
22
22

18
16
20
12
18

52
54
36
56
58

48
42
46
50
52

84
86
86
88
88

80
84
78
84
88

24
24
28
30
32

20
20
24
28
26

62
62
64
64
66

52
56
58
54
58

90
90
92
92
94

88
86
88
86
74

32
36
36
36
36

28
32
26
30
34

68
68
70
70
72

68
54
68
70
68

94
94
96
96
100

94
92
96
96
100

85
TABLE XIX
E F F E C T OF DILUTING BLACK RASPBERRY P U L P
WITH P E C T IN SOLUTION
M old Count (p er cent)

at Dilution:

1:1

2: 1

4: 1

6:1

8.1

10:1

12:1

20

18

14

12

8

8

6

4

20

16

12

10

8

8

4

4

22

18

16

12

10

8

6

4

22

IP

14

12

10

8

6

4

24

20

18

14

10

6

6

2

24

20

16

12

10

8

6

4

28

24

22

18

16

12

8

4

30

28

22

20

16

14

10

6

32

26

22

18

16

12

12

8

32

28

20

20

14

12

10

6

36

32

34

26

22

20

18

18

36

30

28

24

20

18

16

12

36

34

30

26

22

18

14

14

36

26

28

20

16

14

16

8

40

32

24

18

24

18

14

8

42

38

32

28

22

22

18 .

14

42

32

24

24

22

20

20

16

46

32

28

24

22

20

18

16

46

36

34

30

28

24

20

16

48

34

30

28

28

24

22

18

48

36

34

28

24

24

20

16

14:1

T A 3L E XIX (Continued)
M old Count (per cent) at Dilution:
2;1

4:1

6:1

8:1

10:1

12:1

42

36

32

30

26

24

46

3b

32

32

24

26

46

40

36

34

26

26

48

40

38

32

30

26

42

3b

34

30

30

24

50

46

42

36

32

30

r.2

46

40

36

34

32

52

46

42

36

32

30

52

44

42

38

34

32

56

50

44

40

32

30

58

52

48

42

36

30

54

48

44

40

38

32

58

52

48

40

36

32

60

54

50

46

40

36

68

68

72

64

58

56

68

58

56

52

38

32

70

60

58

54

42

36

68

5b

50

46

42

38

72

66

54

46

44

36

64

52

42

40

36

30

76

6b

54

42

40

38

74

70

64

58

50

42

70

66

62

58

48

44

TA BLE XDC (Continued)
M old Count (per cent) a t D ilution:
1: 1

2:1

4:1

6:1

8:1

10:1

12:1

78

76

70

66

60

54

48

82

74

72

68

62

58

52

82

76

70

62

56

54

46

84

76

68

48

28

24

16

84

80

72

64

56

50

48

86

84
i

78

74

66

64

60

86

70

74

68

66

60

56

88

84

74

78

68

64

62

88

88

82

78

74

70

56

90

88

76

72

68

62

58

90

86

80

74

70

64

60

92

88

86

82

76

66

60

94

74

76

70

68

64

50

94

94

92

90

80

74

58

96

96

94

92

72

72

66

96

96

92

56

52

38

32

100

98

84

86

84

76

52

100

100

94

88

84

76

58

E F F E C T OF HARVESTING CONDITIONS ON MOLD COUNT
OF BLACK RASPBERRIES

By
Kuchibhatla L a k sh m i N a r a sim h a m

V*.

AN ABSTRACT
Subm itted to the School of Graduate Studies of M ichigan
State C o lle g e of A g r ic u ltu r e and A pplied S c ie n c e
in p a r tia l fu lfillm e n t of the r e q u ir e m e n ts
fo r the d e g r e e of

DOCTOR OF PHILOSOPHY

D ep artm en t of F o o d T echnology

Y e a r 1949

A pproved

1
KUCHIBHATL.A LAKSHMI NARASIMHAM

ABSTRACT

A study w a s made to d e te r m in e v a r io u s f a c t o r s that m ig h t i n ­
flu e n c e the m o ld count of p r o c e s s e d b la ck r a s p b e r r ie s in M ichigan
during the

s e a s o n s o f 1951 and 1952.

E f f e c t s of d iffe r en t s t a g e s

o f m a tu r ity of b e r r i e s h a r v e s t e d at d iffe r e n t in t e r v a ls after r a in s,
shaking the b lack r a s p b e r r y b u s h e s b e fo r e h a r v e s tin g the fr u it, h o ld ­
ing w et and dry b e r r i e s f o r d iffe r en t in t e r v a ls b e fo r e p r o c e s s in g
and su b jectin g the b e r r i e s to v a r io u s w a t e r - p r e s s u r e w a sh in g s w ere
stu d ied .

The r e la tio n sh ip b e tw e e n v a r io u s dilution m eth od s and m o ld

count in b e r r i e s w a s a ls o d e te r m in ed .

The b e r r i e s w e r e c a r e f u lly

h a r v e s t e d to p r e v e n t any m e c h a n ic a l injury.

They w e r e f r o z e n at

the f a c t o r i e s and brought to M ichigan State C o lle g e f o r fu r th e r e x ­
a m ination.
The f r o z e n b la c k r a s p b e r r i e s w e r e thawed by keeping the c a n s
con taining them in a v e s s e l holding b o ilin g -h o t w a te r .

A fte r thawing,

the s a m p le s w e r e pulped b y a la b o r a to r y pulp er w ith s c r e e n openings
of 0 .0 2 7 in ch in d ia m e t e r .

One p a r t of b la c k r a s p b e r r y pulp obtained

a s above w a s d iluted with two p a r ts b y w eig h t of 3 p e r c en t p e c tin
solu tion .

The pulped b e r r y s a m p le s w e r e e x a m in e d f o r m o ld f i l a ­

m e n t s by the m o d ifie d p r o c e d u r e of the o f f ic ia l m o ld —count m ethod.

KUCHIBHATLA LAKSHMI NAHASIMHAM

ABSTRACT

Soft ripe b la c k r a s p b e r r i e s w e r e found to have h ig h er m old
counts than any o th e r stage of m a tu rity , and s e e m e d to be
sib le fo r the h ig h e r m old counts of the c o m p o s it e

s a m p le s .

respon­
Highly

s ig n ific a n t d if f e r e n c e s betw een m a tu r ity s ta g e s and a definite in ­
c r e a s e in the m o ld count w ith tim e fo llo w in g r a in fa ll w e r e o b s e r v e d ,
in d ica tin g that w e a th e r co n d itio n s p la y an im p ortan t ro le in in flu e n c ing the m o ld count o f b e r r i e s .

Highly sig n ific a n t reduction of m old

count in b e r r i e s w a s obtained b y shaking the b la ck r a s p b e r r y b u sh es
b e f o r e h a r v e s t in g the fru it.

The b e r r i e s of Logan v a r ie t y had h ig h er

m o ld counts than th o se of the C um berland v a r ie t y at all s t a g e s of
m a tu r ity e x c e p t the s h in y -b la c k sta g e .
The tim e that e l a p s e s b e tw e e n h a r v e s tin g the b e r r i e s and
p r o c e s s i n g th em w a s found to have a g r e a t e f f e c t on the m old count
of the final product.

A s ig n if ic a n t in c r e a s e in the m o ld count of the

b e r r i e s and a high c o r r e la t io n b etw e e n holding tim e and the num ber
o f m o ld s in b e r r i e s

w e r e found.

No s ig n ific a n t d iffe r e n c e b etw een

holding the w e t and d r y b e r r i e s w a s o b s e r v e d in th is study.
W ashing s e e m e d to b e e f f e c t iv e in red ucing the m o ld count
of b e r r ie s.

B la c k r a s p b e r r i e s

su b je c te d to w a te r w ashing by sh ak er

w a s h e r , w a te r s p r a y on the c o n v e y o r b e lt, and sink w ash in g with

KUCHIBHATLA LAKSHMI NARASIMHAM

ABSTRACT

thorough agitation of the fru it w as found to be the m o s t e ffectiv e
m ethod fo r reducing the m old count.
No sig n ific a n t d iffe r e n c e s w ere obtained when m old counts d e ­
te r m in ed by m od ified technique w ere com pared with th o se obtained
by the o ffic ia l m ethod.

Adding differen t am ounts of p e c tin solution

to b la ck r a sp b e r r y pulp lo w e r e d the m old count, but its d e c r e a s e
w a s not in d ir e c t proportion to the amounts of p ectin solution added.