Experiment on Digestion of \;Vhale Meat by Koji-moulcl
Saburo Tsukamoto
Introduction.
It has already been reported (Akiya, Ishikawa, Tejima) that whale
pancreas can be used for manufacturing peptone from whale meat and aproduct suitable for bacteria culture can be obtained by digesting whale
meat with this enzyme.
However, the proportion of pancreas compared with the size of thewhale is very small, 3-5 kg in the case of sp2rm whale of about 45 ft inlength and 10 kg in the case of sei whale of about the same size. Also,
the total quantity of whale pancreas in the country is very small so thatthe production of peptone is naturally limited by the quantity of pancreas.
Furthermore, pancreas is an important raw material for pharmaceuticals
such as protease, insulin which is the special medicine for diabetics, etc,
and since there is much use for it in the future, if is necessary to find an
enzyme source other than pancreas, for manufacturing peptone.
The authors' attention was turned to koji-mould (Aspergillus Oryzae),
which is relatively easy to obtain and easy to manufacture, as a substitutefor this pancreatin.
The reaction of koji-mould on protein, by which the protein is decom-

posed into amino acids by the protease, is widely used in various fermentation industry, but when whale meat is used as a source of proteill' anddecomposed, peptone, peptide and amino acids are produced. The fact that
peptone is suitable for bacteria culture by this method has already been
explained (Tejima).
In carrying on this decomp::isition, there is a great difference in its
enzymic action according to kind of koji-mould, kind of culture substrate,
culture conditions, enzyme reaction conditions, and pretreatment conditionsof whale meat, etc.
The object of this experiment is to find out these conditions. Protein
will first become water soluble peptone by the reaction of enzyme so thatthe degree of decomposition at the beginning can be determined by theamount of water soluble portion.

Saburo, Tsukamoto

Therefore, roughly, the quantity of peptone can be calculated by evaporating and drying the water soluble substance produced by decompositionof whale meat by koji-mould.
In this e:xperiment, sweet potato flour and potato starch were chosen
as culture substrate and whale meat broth was used for mixing in this.
Ordinarily, rice is used for koji-mould culture, but the present condition in
the country does not permit its use.
Tejima, used soy bean meal but
this is principally and imported goods so it was assumed to be rather undependable as raw material. Also, it is a known fact that the koji-mould
will depend on the kind of enzyme produced by different substrate sothat whale meat broth was mixed in it in order to produce as muchprotease. As explained later, the decomposition power was stronger themore whale meat broth used, as anticipated.
Experiment.
Koji-mould Culture.
As substrate, three types were used, one with sweet potato flour

kneaded with equal amount of water, formed into pellets the size of soy
bean and steamed .in an oven, the second with sweet potato flour kneadedwith half its quantity of water and half its quantity of whale meat broth,and the third with sweet potato flour kneaded with equal amount of whale
meat broth. Whale meat broth referred to here is meat broth produced
by decomposing finely chopped whale meat with heat. The object is tosupplement the protein in sweet potato flour and also because it was
assumed that it will strengthen the protease in the koji-mould.
As coditions for culture, the substrate steamed as above in cooled
and koji-mould spores cultured with glutinous rice is shaken on it andexperiment on rate if decomposition of whale meat experimented withthose left standing for 1 day, 2 days and 3 days at 31-33"C.
In regard to propagation of koji-mould when whale meat broth is not
added, only a slight formation of mycelium with te 1 day culture is observed, entirely covered with te 2 days culture and spores were well formed
with 3 days culture, but when whale meat broth was added, it because
more active, such that 1 day culture was entirely covered with myceliumand spores were entirely formed with 2 days culture.
Digestion of whale meat.

Experiment on Digestion of whale meat by Koji-mould

63

Digestion was caried on by the following method with koji-mould cultured by the above method. For each 5 g of sweet potato flour used forculture, 100 g of finely chopped frozen fin whale meat is boiled, filteredwith a cloth, 100 c.c. of sterilized water is added to the insoluble matter,that is, meat protein, boiled to sterilize, koji-mould cultured by the above
method and a small amount of toluol is added and preserved at 31 -33°C .
Digestion time was divided {nto three stages, 48 hours, 74 hours and120 hours.
After digestion, this is filtered with suction, using cloth toseparate the soluble and insoluble p::>rtions and each partion is evaporated,dried (105cC) and weighed.
Peptone was calculated by the following formula :Peptone (g)= {Resid~~_(gydi-ous) (g)-dried residue (g)} x
filtrate (g)dried filtrate (g) +dried filtrate (g)Table 1.
Koji1 No. ofI .
: .
Dried 1 Residue ' Dried i Peptone ..
moul~ cul-j day~ di- Kmd of'. Filtrate\ filtrate I (hydrous)1 residue ',((~):-Cd)+1)
1ture time ! gest10n/ culture;

(a)

I(b)

,-- ---,l---;---i____ i1Al1I

99 g'aB

167 g1II,~ - I"'6 g )J_ _ _ _ 1_ _ _ ,I---,I 89

5.2'71I\I Substrate is 5g

potato flour
6·35 g II sweet
kneaded with 5 g
I water_I Substr--at~e_u_s_ed.--..,---is: 5 g sweet potato

7.6

I flour kneaded with----! 2.5 g meat extract:si.ibsti-ate i.isedls-

29

I 2.5 g water andi
No. 1
I

24 hours :94

C_ _ _ 1 _ _ _ _ _ 1, _ _ _ _ _ _cultureAb(3 days)

B
C.

5·1cB

78

----1(2-d~;s)T-:

5.397
I 125

5.7
6.1

ii

:11(113 c.c.)li
ks 4 85c.c.) ;-l-:: -,

I·61
61
67

I(5 days)

I
1.

25
r,525

i:,

_i21.l6.0

62,6.073

1; 5 g sweet potato

8·0i flour kneaded withi ·-~ ~-!llea!_~"}(tr;ict;_

20.2

1
1·

7.3
7.85
8.15

i Water added toimeat was too much

1.1

8.2

62
60

I~C I 81~~ i! 56.0·3
I______· (79 c~c.) I

21.8

1

9.6

64
::~ -------------~:~5-23II cI10060)_ _ _ _ _i ___ J_ _ _ _ I_ _• _ ---63
48 hIA96
4.9ours.IbB
84 I
070(3 days)l1
5.
66
culture__c__ [_~i 5.7____I__i60

1cIIC

No. 2·125•5

1_ _ _ _ _ : _ _ _ _ _ _ . _ _ _ _ _ 1
1I 105

1---A--: 1 fr-· --5~5(5 days)

I6·2

63
62
69

Remarksl__J<i}__I '") X(l>)1...,,.-.---~,-------.--=,--

1ii (2 days)

4.5g

\(c)

23
23

--- --- ----

8.2

22

7.0
7.85
8.6

22

21
20.6
19.5
19.5

Filtering somewhat diffcultII

8.3
8.8
10.0

J ____---•

64

Saburo, Tsukamoto

A. : 100
B: 93 Ii (90 c.c.) :a(2 days)c-----

A

No. 372 hours
cultureb(3 days)

I 97___ I _ _B

:59

6.0
6.6

I!

I

20.7 I
16.9 '
16.9i

Filtering somewhat
difficult

9.5

21
21

i-·----·.

!

8.. 4

9.1

,______ ,-· I Filtering somewhat
I 90c89, 61
I (87 c.c.) i•
199,6.6
Ic . '---~9 _I
I 91 . !

A

6.1

1.2
6.0/__-~·
73·I (S days) B \ 84 6.8 66_I (8_ ~ays ~--~~ _ 108--~~ 7.8 _ -~
2i

19
19.1

difficult•

9.1
10.25
10.0

I

15.0 :
13.2

.

10.1

I 10.5.Filtering somewhat:difficult (c) had considerable moisture-;-~---,--!

11.2

Experimental result is as indicated in Table 1.
As can be seen from the above table, digestion is greater when amount of whale meat broth added is greater and \vhen the culture time islonger. Furthermore, digestion ·will be greater and more soluble matter
obtained when digestion time is longer. However, if the digestion time is·long, the undecomposed portion will become considerably less and the totalof this and the soluble portion will be reduced. It is believed that this isdue to the fact that the. greater part of the soluble .protein is further
decomposed and gasified into ammonia gas, etc. Also change in quantityof soluble portion will be retarded when decomposition is continued further.
That is, the culture time of koji-mould, in the condition of digestion, had
the greatest effect and the effect of time in digestion increased greatly
during the first 2 days and becomes very small after that.
In this experiment, 10.5 g of soluble portion was obtained from 100 gof frozen, fresh meat when decomposition was greatest.
The above digestion was carried on at 33"C, but next, digestion wascarried on with sperm whale meat under the best conditions of the above
experiment, changing the temperature to 37'C and 42°C, the previousexperiment was carried on at pH of about 7, but dilute HSO, was addedin this experiment in order to carry it out at pH 4.2.
Furt:tJ.ermore, as substrate potato starch was used instead of sweetpotato flour.
The result is as indicated in Table 2.
Table 3 indicates the principal curves of Tables l and 2.
In this experiment, it was difficult to filter after digestion so theunreacted slimy matter was separated with a centifugal separator.

•65 .

ExPeriment on Digestion of whale meat by Koji-mould
Table 2.

I

Driedt Substrat e for k OJl·.. Di~estion. I Filltrate\ Dne. d Slimy
Decomposition
tern-.
matter Slimy Calculated! Re·perature [ _~oul~ cul~u~e __ time_[ _ _ _ I filtrate (hydrous) matter peptone. marksj
Sweet potato flour
5.3g+whale meata (2 days) llOg
60g
17.0g
7.31g
brothb (3days)

112.3

6.2

60.8

13.3

8.82

c (5 days)

114.8

7.3

55

9.5

10.2

d (5days)93.0
whale meat broth--·swee-t potato flour+whale meat broth e (5 days) 115.7
Sweet potato floura (2days)J 115.0+whale meat
broth

5.6

60.7

13.8

8.43

6.9

66.2

20.0

9.6

No. 137°C

PoTiios"Fircfi-+b (3 days)

No. 2120.9

7.5I 57

16.2

10.18

7.6

57.0

12.7

10.8

8.3

47.3

9.0

10.9

6.8

53.9

10.2

9.3

7.2

66.6

19.4

9.9

-----c (5 days)

42°C

127.0

Potato starch +d (5 days) 119.0
whale meat broth--Sweet Potato flour e (5 days) 122.5+whale meat broth-.

(During digestion, 0.3 g of various oils and fats were obtained)
Table 3.
10.9

Peptone produced from100 g of frozen whale l(! - .
meat (g)9'87I___,__ _ _....__ __,__ · - - - - 1 . - - - ' - j12·3•f3

Digestion time for whale meat

It can be observed from this table that maximum digestion is at 42°C,digestion is somewhat less at pH 4.2 than at pH 7 and less when potato

Saburo Tsukamotostarch was used than when sweet p::>tato flour was used. It is assumed
that the koji-mould did not propagate fully into the interior because of theformation of gel in case of starch, and also, the culture method was somewhat difficult due to gel formation.
Conculsion.
The following conculsion is drawn from the above experiments. Thebest condition for producing peptone by digestion whale meat with sweet
p::>tato koji-mould, within the sphere of this experiment, are as follows :1. To use a large quantity of whale meat broth with sweet potato
flour in producing koji-mould, and to use as much time in culture.
2. Digestion temperature is ·about 42°C.
3. Digestion time is about 5 days.
4. Care must be taken to prevent abnormal fermentation.
About 10% of peptone can be obtained from frozen whale meat, andsince the protein content of frozen whale meat is about 20%, about 59%is decomposed.
In cn.oclusion, sincere thanks is experessed to Dr. Maruyama for his
advice in this research.