Declerck, D.

Declerck, D.,

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Canned mangrove crab (Scylla Serrata) : a product with limited shelf life /

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MINISTERIE VAN LANDBOUW
BESTUUR VOOR LANDBOUWKUNDIG ONDERZOEK
KOMMISSIE VOOR TOEGEPAST WETENSCHAPPELIJK ONDERZOEK
IN DE ZEEV ISSER IJ (T. W. O. Z.)
(Voorzitter: F. LIEVENS, directeur-generaal)
CANNED MANGROVE CRAB (SCYLLA SERRATA) : 
A PRODUCT WiTH LIMITED SHELF LIFE
D. DECLERCK
ONDERWERKGROEP
„VtSVERWERKENDE BEDRtJVEN - VOORVERPAKKtNG V)S" (t.W.O.N.L.)
Mededelingen van het Rijksstation voor Zeevisserij (C. L. O. Gent) 
Publikatie nr 111-VB/VV (t.W.O.N.L.) 16, 1975
Paper presented at the Sixth Meeting of W. E. F. T. A.,
Ostend, September 1975
MINISTERIE VAN LANDBOUW
BESTUUR VOOR LANDBOUWKUNDIG ONDERZOEK
KOMMISSIE VOOR TOEGEPAST WETENSCHAPPELIJK ONDERZOEK
IN DE ZEEV ISSER IJ (T. W. O. Z.)
(Voorzitter: F. LIEVENS, directeur-generaal)
CANNED MANGROVE CRAB (SCYLLA SERRATA) : 
A PRODUCT WITH LIMITED SHELF LIFE
D. DECLERCK
ONDERWERKGROEP
„VtSVERWERKENDE BEDRtJVEN - VOORVERPAKKtNG V!S" (t.W.O.N.L.)
Mededelingen van het Rijksstation voor Zeevisserij (C. L. O. Gent) 
Publikatie nr 111-VB/VV (I.W.O.N.L.) 16, 1975
Paper presented at the Sixth Meeting of W. E. F. T. A.,
Ostend, September 1975
D/1975/0889/5

I N T R O D U C T IO N .
M a n g r o v e  c r a b  m é a t  (S cy l l a  s e r r a t a )  o f  M a l a y s i a n  o r i g i n  p r e s e n t e d  
e s p e c i a l l y  a t  th e  b e g i n n i n g  c e r t a i n  p r o c e s s i n g  a n d  s t o r a g e  p r o b l e m s  fo r  
t h e  B e l g i a n  c a n n i n g  i n d u s t r y .
In t h i s  c o n t e x t  t h e  q u a l i t y  o f  th e  r a w  m a t e  r i a l  a s  w e l l  a s  t h a t  of 
the  c a n n e d  p r o d u c t  w a s  e x a m i n e d .  T h e  a u t o c l a v e d  c a n s  w e r e  s t o r e d  
d u r i n g  f o u r  m o n t h s  a t  - 1 8 ° ,  +5° ,  +20° ,  +35° a n d  + 50° C.
In o r d e r  to  c l e a r  up s o m e  d i f f i c u l t é s  in  t h e  i n t e r p r é t a t i o n  o f  th e  
r e s u l t s ,  a s e c o n d  s e r i e s  o f  e x p e r i m e n t s  w a s  c a r r i e d  out  to  fo l low m i c r o  
b i a l  d e v e l o p m e n t  a t  t h e  b e g in n i n g  of  s t o r a g e  a t  50° C.
F o r  e a c h  s e r i e s  th e  q u a l i t y  of  the  p r o d u c t  w a s  d e t e r m i n e d .  A 
n u m b e r  o f  t e s t s  w a s  a l s o  c a r r i e d  ou t  to  a s c e r t a i n  t h e  m i c r o b i o l o g i c a l  
s a f e t y  of  t h e  p r o d u c t .
1. M a t e r i a l s  an d  M e t h o d s .
1 . 1 .  T e c h n o l o g i c a l  p r o c e d u r e .
T h e  c r a b  m e a t  u s e d  fo r  c a n n i n g  w a s  f r o z e n  a n d  p a c k e d  in  p l a s t i c  
f i l m  on a r r i v a i  in  t h e  p r o c e s s i n g  p la n t .
A f t e r  t h a w i n g  a t  10° C, 275 m l  c a n s  w e r e  f i l l ed  w i th  c r a b  m e a t  
a n d  60 m l  l i q u i d  w a s  a d d ed .
T h e  l i q u i d  c o n t a i n e d  s a i t ,  a c i d s  a n d  s o m e  s w e e t e n e r .  A f t e r  f i l l ing  
c o m m e r c i a l  s t e r i l i z a t i o n  w a s  c a r r i e d  out  fo r  70 to 80 m i n u t e s  at  110° C
A t  th e  e n d  o f  t h e  h e a t i n g  p r o c e s  s c h l o r i n a t e d  c o o l  w a t e r  w a s  g r a -  
d u a l l y  i n t r o d u c e d  i n t o  t h e  r e t o r t  a n d  o v e r p r e s s u r e  w a s  r e d u c e d  s lo w ly  
a s  t h e  p r o d u c t  w a s  co o le d .
F o r  th e  e x p e r i m e n t  100 c a n s  w e r e  u s e d  an d  t r e a t e d  a s  fo l lo w s
20 c a n s w e r e k e p t fo r 4 m o n th s in f r e e z e r  (-18 ° c )
10 c a n s w e r e k e p t fo r 2 m o n th s in r e f r i g e r a t o r (+5°
10 c a n s w e r e k e p t fo r 4 m o n th s in r e f r i g e r a t o r (+5°
10 c a n s w e r e k e p t fo r 2 m o n th s a t 20° C
10 c a n s w e r e k e p t fo r 4 m o n th s a t 20° C
10 c a n s w e r e k e p t fo r 2 m o n th s a t 35* C
10 c a n s w e r e k e p t fo r 4 m o n th s a t 35° C
10 c a n s w e r e k e p t fo r 2 m o n th s a t 50° C
10 c a n s w e r e k e p t fo r 4 m o n th s a t 50° C
1 . 2 . M e th o d s .
- D r y  m a t t e r  a n d  s a i t  : by th e  m e th o d s  o f  th e  A O A C  (1).
- T o ta l  v o la t i l e  a c i d s  (VAN) : by  th e  m e th o d  o f  th e  A O A C  (2) bu t  u s in g  
A n to n a c o p o u lo s '  s t i l l  (3) ; 500 m l  w e r e  d i s t i l l e d  o v e r .
- T o ta l  v o l a t i l e  b a s e s  (TVN) : by t h e  m e th o d  o f  L u c k e  a n d  G e id e l  (4) 
a s  m o d i f i e d  by A n to n a c o p o u lo s  (5).
- A m m o n ia  : by  a c c e l e r a t e d  m i c r o d i f f u s io n  ( 6 ).
-  M ic r o b i o lo g i c a l  a s s e s s m e n t s  : T o ta l  a e r o b i c ,  a n a e r o b i c  b a c t e r i a l  
c o u n ts  w e r e  m a d e  by i n o c u l a t io n  in  P e t r i  d i s h e s  c o n ta in in g  P l a t e  
C oun t  A g a r .  T h e  G a s P a k  a n a e r o b i c  s y s t e m  (B B C , C o c k e y s v i l l e ,  
M a r y la n d ,  USA) w a s  u s e d  f o r  a n a e r o b i c  c o u n ts .  I n c u b a t io n s  l a s t e d  
fo r  72 h r s  a t  30° C.
S a fe ty  t e s t s  w e r e  c a r r i e d  ou t  w i th  d é t e c t io n  r e a c t i o n s  d e s c r i b e d  by 
M o s s e l  a n d  T a m i n g a  (7) fo r  E n t e r o b a c t e r i a c e a e , C o l i f o r m s ,  S a lm o n - 
e l l a e , V ib r io  p a r a h e a m o l y t i c u s  a n d  S t a p h y lo c o c c u s  a u r e u s .
T h e  e n r i c h m e n t  a n d  i s o l a t i o n  m e d i a  fo r  th e  d é t e c t io n  o f  B a c i l l a c e a e  
w a s  r e a l i s e d  w i th  " B r a i n  h e a r t  i n f u s io n "  + 2 g r  s o lu b le  s t a r e l s  an d  
" P e p to n e  l a c t o s e  y e a s t  e x t r a c t  a g a r "  w i th  a d d i t i o n a l  s t a r c h  an d  
b ro w n  c r e s o l  p u r p l e  ( I a t r e a ) .
T h e  m e d i a  o f  R o s e n o w  ( I a t r e a )  a n d  " G lu c o s e  y e a r t - b e e f  e x t r a c t  a g a r "  
( I a t r e a )  w i th  a d d i t i o n a l  h o r s e  b lo o d  w e r e  u s e d  fo r  th e  i s o l a t i o n  of 
C l o s t r i d i u m .  F u r t h e r  d é t e r m i n a t i o n  s u c h  a s  a m y l a s e  a c t i v i t y ,  H^S
p r o d u c t i o n ,  i n d o le  f o r m a t i o n ,  r é d u c t i o n  o f  n i t r a t e  a n d  f e r m e n t a t i o n  
, r e a c t i o n s  w e r e  c a r r i e d  ou t.
-  O r g a n o le p t i c  j u d g m e n t  : w a s  p e r f o r m e d  by  a p a n e l  o f  fo u r  m e m b e r s  
on o d o u r ,  t e x t u r e ,  c o lo u r ,  t a s t e ,  g a s ,  l iq u id ,  b l a c k e n in g  a n d  sw e l l in g .
2. R e s u l t s  a n d  d i s c u s s i o n .
2. 1. D r y  m a t t e r  a n d  s a i t  c o n te n t .
T a b le  1 - D r y  m a t t e r  a n d  s a i t  c o n te n t  o f  th e  r a w  m a t e r i a l  a n d  c a n n e d  
c r a b  m e a t  in  %
C r a b D r y  m a t t e r  % S a i t  c o n te n t  %
F  r o z e n 14 0. 56
C a n n e d 13. 1 1 . 1
O nly  13 .1  p e r c e n t  d r y  m a t t e r  in  th e  c a n n e d  p r o d u c t  w a s  n o te d .
T h i s  d r y  m a t t e r  c o n te n t  i s  v e r y  low  a n d  i s  t y p i c a l  fo r  t h e  p r o d u c t  
e x a m in e d .
2. 2. O r g a n o le p t i c  a s s e s s m e n t .
T h e  r e s u l t s  o f  t h e  o r g a n o l e p t i c a l  j u d g m e n t s  ( t a b le s  2 a n d  3) sh o w e d  
th a t  t h e r e  i s  no  c h a n g e  i n  th e  c a n s  s t o r e d  f o r  2 a n d  4 m o n th s  a t  -1 8 °  
a n d  + 5° C.
A s  r e g a r d s  th e  c a n s  s t o r e d  a t  20° C, t e n  p e r c e n t  c h a n g e d  in  
o d o u r  a n d  f l a v o u r  a f t e r  tw o m o n t h s '  s t o r a g e .  D é f in i t iv e  c h a n g e s  in  
f l a v o u r  a n d  o d o u r  w e r e  n o te d  a f t e r  fo u r  m o n th s  : th e  c a n n e d  c r a b  
r e a c h e d  a l m o s t  th e  l i m i t  o f a c c e p ta b i l i t y .
T h e  c a n s  k e p t  a t  35° a n d  50° C w e r e  a l r e a d y  of b a d  q u a l i t y  a f t e r  
tw o  m o n t h s '  s t o r a g e .  S w e l l in g  w a s  o n ly  o b s e r v e d  in  th e  c a n s  s t o r e d  
a t  50° C.
2. 3. C h e m ic a l  r e s u l t s .
T h e  r e s u l t s  o f  th e  pH, NH^, T M A , T V N  a n d  VA N  d é t e r m i n a t i o n s
( t a b le s  4, 5, 6 , 7, 8 ) c a r r i e d  ou t  a f t e r  2 a n d  4 m o n t h s  c o n f i r m e d  the
o r g a n o l e p t i c  j u d g m e n t s .
T h e  NH^, T M A , T V N  c o n te n t  i n c r e a s e d  a f t e r  t h e  c a n n in g  p r o c e s s  : 
in  th e  r a w  m a t e r i a l  6 . 9 m g  N %, 1. 05 m g  N % a n d  1 1 .1  m g  N % w e r e
n o te d  r e s p e c t i v e l y .  A f t e r  c a n n in g  1 2 .3  m g  N %, 3 . 8  m g  N % an d  25 m g
N % w e r e  a t t a in e d .
T h e  c o n te n t  o f  VAN on th e  c o n t r a r y  d e c r e a s e d  a f t e r  p r o c e s s i n g .
T h i s  p h e n o m e n o n  i s  due  to  th e  fa c t  t h a t  h e a t e d  c a n s  w e r e  c l o s e d  o n ly  
a t  th e  en d  o f  th e  p r o c e s s .
A d e c r e a s e  of pH v a l u e s  ( ta b le  4) w a s  n o te d  o n ly  in  th e  c a n s  s t o r e d  
a t  3 5° a n d  50° C.
A h ig h  i n c r e a s e  o f  a m m o n ia ,  t o t a l  v o la t i l e  b a s e s  a n d  v o la t i l e  a c i d s  
c o n te n t  ( t a b le  5, 7 a n d  8 ) w a s  n o te d  f o r  th e  c a n s  s t o r e d  a t  50° C. In 
m e s o p h i l i c  c o n d i t io n s ,  a m m o n ia ,  TV N  a n d  VAN p r o d u c t i o n  w a s  s m a l l e r .
C o n s i d e r in g  th e  tw o  s t o r a g e  p e r i o d s  (2 a n d  4 m o n th s )  no g r e a t  
d i f f é r e n c e s  in  NH^, T V N  a n d  VAN c o n te n t  c o u ld  be n o te d  fo r  c a n s  s t o r e d  
a t  50° C. F o r  t h i s  i n c u b a t io n  t e m p e r a t u r e  a l t é r a t i o n  o c c u r r e d  e a r l y  
d u r in g  th e  s t o r a g e  p e r i o d  a n d  p r o g r e s s e d  v e r y  s lo w ly  a f t e r w a r d s .
D é t e r m i n a t i o n s  o f  TM A  c o n te n t  ( t a b le  6 ) g a v e  no  i n f o r m a t i o n  a s  
to  th e  q u a l i ty  o f  c a n n e d  c r a b .  TM A  c o n te n t  o f  a l l  e x a m in e d  c a n s  w a s  
r a t h e r  low . A n  a d d i t i o n a l  e x p e r i m e n t  sh o w e d  t h a t  a l l  TM A O  w a s  c o n -  
v e r t e d  in to  TM A  a f t e r  tw o  m o n th s  o f  s t o r a g e .  T h i s  p r o v e s  t h a t  s o m e  
m i c r o b i o l o g i c a l  a c t i v i t y  w a s  p r e s e n t .
In  g é n é r a l  a l t é r a t i o n  p r o d u c t s  w e r e  v e r y  h ig h  in  c a n s  s t o r e d  
u n d e r  t h e r m o p h i l i c  c o n d i t i o n s  (50° C) ; h o w e v e r  t h e s e  w e r e  s m a l l e r  
^ u t  s t i l l  v e r y  i m p o r t a n t ,  u n d e r  m e s o p h i l i c  c o n d i t io n s  (35* C).
2 . 4 .  M i c r o b i o lo g i c a l  r e s u l t s .
T o t a l  a e r o b i c  a n d  a n a e r o b i c  b a c t e r i a l  c o u n ts  w e r e  g e n e r a l l y  
z e r o  f o r  a i l  i n c u b a t e d  c a n s .
A e r o b i c  m i c r o - o r g n i s m s  w e r d  c o u n te d  o n ly  i n  t h e  c a n s  i n c u b a t e d  
a t  20* C.
T h i s  i n d i c a t e s  t h a t  t h e  s p o r e s  d id  n o t  d e v e lo p  in  t h e  c a n s  i n ­
c u b a t e d  a t  5° C, a n d  t h a t  th e  m i c r o - o r g a n i s m s  d e v e lo p e d  a n d  l a t e r  
d ie d  in  t h e  c a n s  k e p t  a t  50* C.
T h i s  p h e n o m e n o n  w a s  c l e a r e d  u p  d u r in g  a n  a d d i t i o n a l  s e r i e s  o f  
e x p e r i m e n t s  c a r r i e d  ou t  to  fo l low  m i c r o b i o l o g i c a l  d e v e l o p m e n t  a t  the  
b e g in n in g  o f  s t o r a g e  o f  th e  c a n s  s t o r e d  a t  50° C.
C o m m e r c i a l  s t e r i l i s e d  c r a b  m e a t  w a s  p u t  a c c e p t i c a l l y  in  an  e r l e r -  
m e y e r .  T h e  e r l e m e y e r  w a s  p l a c e d  i n  a n  a n a e r o b i c  j a r  a n d  i n c u b a t e d  
a t  50* C.
E v e r y  f o u r  h o u r s  a  s a m p l e  w a s  e x a m e d  f o r  pH, NH ^, T M A , T V N , 
VAN, a e r o b i c  a n d  a n a e r o b i c  d e v e lo p m e n t .
pH  v a l u e s  d e c r e a s e d  a f t e r  160 h o u r s .
F o r m a t i o n  o f  NH ^, T V N  a n d  V AN i n c r e a s e d  g r a d u a l l y .  T M  A f o r m a t i o n  
r e a c h e d  i t s  m a x i m u m  a f t e r  36 h o u r s .  T h i s  w a s  i n  fu l l  a g r e e m e n t  w i th  
th e  r e s u l t s  o f  th e  f i r s t  e x p e r i m e n t  ( t a b le  9 ).
A t  th e  b e g in n in g  of th e  in c u b a t io n  p e r i o d  n o  b a c t e r i a  w e r e  c o u n te d
( ta b le  10). A f t e r  20 h o u r s ,  g ro w th  o f  a e r o b i c  a s  w e l l  a s  a n a e r o b i c
b a c t e r i a  w a s  d e t e c t e d .  T h e  m a x i m u m  n u m b e r  o f  a n a e r o b i c  a n d  a e r o b i c
b a c t e r i a  w a s  c o u n te d  a f t e r  28  h o u r s .  A t  th e  e n d  o f  t h e  in c u b a t io n
p e r i o d  (160 h o u r s )  n o  b a c t e r i a  w e r e  d e t e c t e d  in  th e  c r a b  m e a t .
A l l  th e  t e s t s  p e r f o r m e d  to  d e t e r m i n e  th e  s a f e ty  o f  th e  c a n n e d  
p r o d u c t  w e r e  n e g a t iv e .  I t  c o u ld  t h u s  b e  c o n c lu d e d  t h a t  th e  c r a b  w a s  
c a n n e d  u n d e r  a d e q u a t e  h y g ie n ic  c o n d i t io n s .
T a b le  11 g iv e s  th e  r e s u l t s  o f  t h e  n u m b e r s  o f  c a n s  p o s i t i v e  fo r  
B a c i l l u s  a n d  C l o s t r id i u m .
Id e n t i f i c a t i o n  t e s t s  on t h e  i s o l a t e d  c o lo n i e s  i n d i c a t e d  C l o s t r i d i u m  
s p o r o g e n e s  ( t a b le  12). F u r t h e r  i d e n t i f i c a t io n  t e s t s  on  B a c i l l u s  w e r e  n o t  
p e r f o r m e d .
T h e  g é n é r a l  c o n c lu s io n  o f  t h e s e  t e s t s  w a s  t h a t  M a n g r o v e  c r a b  c a n n e d  
in  th e  c o n d i t io n s  d e s c r i b e d  h e r e  h a s  a  l i m i t e d  s h e l f  l i f e  a t  20° C a n d  
sh o u ld  be  k e p t  c o o l  .
F u r t h e r  i n v e s t i g a t i o n s  a r e  n e c e s s a r y  to  e s t a b l i s h  th e  o p t im a l  
s t o r a g e  t e m p e r a t u r e .
A C K N O W L E D G M E N T .
T h i s  w o r k  i s  p a r t  o f  the  p r o g r a m m e  o f  th e  " C o m m i s s i e  v o o r  T o e ­
g e p a s t  W e t e n s c h a p p e l i j k  O n d e r z o e k  in  de Z e e v i s s e r i j "  B r u s s e l s  a n d  h a s  
b e e n  s u p p o r t e d  by g r a n t s  f r o m  th e  " I n s t i t u u t  v o o r  A a n m o e d ig in g  v a n  h e t  
W e te n s c h a p p e l i j k  O n d e r z o e k  in  N i jv e r h e i d  en  L a n d b o u w " ,  B r u s s e l s .
T h e  a u t h o r  w i s h e s  to  th a n k  P r o f .  R. M e s s e l y  a n d  C. D e w i c k e r e  
( g r a d u a t e  H. T. I. B r u g e s )  f o r  u s e f u l  a d v i s e  a n d  c o l l a b o r a t i o n .
L I T E R A T U R E .
1. M e th o d s  o f  t h e  A O A C  (1970) : A O A C  W a s h in g to n  l l t h  E d .
2. M e th o d s  o f  th e  A O A C  ( I9 6 0 )  : A O A C  W a s h in g to n  9 th  E d .
3. A n to n a c o p o u lo s ,  N. , Z . L e b e n s m i t t . -  U n te r s u c h .  u. F o r s c h .  , 113, 
113 ( I9 6 0 ) .
4. L u c k e ,  F .  a n d  G e id e l ,  W. , Z .  L e b e n s m i t t .  - U n te r s u c h .  u. F o r s c h .  , 
70, 441 (1935).
5. A n to n a c o p o u lo s ,  N. , in  H a n d b u c h  d e r  L e b e n s m i t t e l c h e m i e ,  V ol.  H l /2 ,  
S p r i n g e r  V e r l a g ,  B e r l i n  (1968).
6 . V y n c k e ,  W. : F i s h .  N ew s Int.  7, 49 (1968).
7. M o s s e l ,  A. A . a n d  T a m m i n g a ,  S. K. (1973) : M e th o d e n  v o o r  h e t
m i c r o b i o l o g i s c h  o n d e r z o e k  v a n  l e v e n s m i d d e l e n .  P .  C. N o o r d e r v l i e t  
Z e i s t .
Storage
temperature
Odour Cotour Ftavour Continence Gas
mt
Liquid
mt
Btackening Swetting
-18 °C 
and 
+ 5°C
no
change
no
change
no 
cha nge
no
change
3.5 60 no
btackeni ng
none
+ 20 °C off - odours 
( !  : tO )
no
change
off - ftavour s
( t : to)
no
change
3.5 60 no
btackening
none
+ 35 °C off-odours 
(tO ; tO)
some
darkness
off -ftavours
( tO : )0)
decreased ---- 96 no
btackening
none
t 50°C putric odours 
(10:t0)
definitely
dark
putric ftavours 
00:10)
décomposé d pressure when 
opening cans
11 2 btackening swetted
Storage
temperature
Odour Cotour Ftavour Consistence Gas
mt
Liquid
m(
Btackening SweHing
.1 8 °C 
and
+ 5°C
no
change
no
change
no
change
no
change
3.5 6 0 no
btackening
none
t 20 °C
some 
off - odours
(10.-10)
no
change
some 
off —ftavours
(10:10)
no
change
3.5 60 no
btackening
none
+ 35 °C off .odours 
( 10 10)
some
darkness
off-f tavours 
( 10 10)
decreased 97 no
btackening
none
+ 50'C putric odours 
( 10 :10)
definitety
dark
putric ftavours 
(10:10)
decomposed pressure when 
opening cans
118 btackening swetted
S to rag e  t ime 
in m onths
Storage t e mperature s
- ) 8 * C + 5 ° C + 20 ° C + 35 °C  ^ 50 *C
2 6.9 6.9 6.9 6.6 6.3
4 6.9 6.9 6.8 6.4 6.2
Storage tim e 
in months
S t orage e m perature s
- ) 8 ° C + 5 °C + 20 °C + 3 6 °C ^-50 °C
2 '1.3 " . 7 13.) '4 .8 41.3
4 12.3 !2 13.6 18.1 46.6
four months stored cans at different temperatures.
Storage time 
in months
Storage temperatures
- 1 a °C + 5 *C + 20 *C + 35 *C + 50 *C
2 3.8 7.9 11.5 11.8 11.1
4 3.8 5.4 !!.5 13.8 10.9
four months stored cans at different temperatures.
Storage time 
in months
Storage temperatures
- 1 8  °C + 5°C + 20°C + 35°C + 50 °C
2 2 5.2 26 26.7 30.7 59 6
4 25.2 2 5.4 29.8 36.6 63.6
of the two and four month: stored cans at different temperatures.
St orage time 
in months
Storage temperatures
2
- 1 8 °C + 5 °C + 20 °C + 35 °C + 50 °C
!2.5 16.5 )6.8 29.5 )5!^
4 )2.5 )6^ )6.) 29.6 ]79.3
Tabte 9 ! Evotution of chem ica t  re su t ts  of crab meat  dur ing anaerobic  
s torage at 50 ° C .
Hours
PH "  H3 
mg N°/o
TMA
mgN"/.
TVN 
mg N°/°
V A N
mt NaOH Q01N/l00gmeat
0 7.1 11.20 7.66 24.08 21.6
4 7.) 13.0 8 8.28 25.06 240
12 7.0 15J2 8.90 2 5.34 26.4
20 7.) 15.90 9.96 25.88 30.0
2 8 7.0 16.12 10.3 5 26.88 3 8.4
36 7.1 1 6.96 10.59 2 7.86 4 2.0
44 7.0 17.15 10.66 29.6 8 46.0
52 6.8 18.29 10.55 32.20 56.4
60 6.9 21.78 9.18 32.6 2 61.2
)60 6.2 22.8 9.20 3180 66.3
c o u n t s  of  c r a b  m e a t  dur i ng  s t orage  at  50°C.
Hours
Aerobic
C o u n t s
Anaer ob i c
C o u n t s
0 0 0
2 0 3 0 0 0 0 1 6 0 0
2 8 3 5 0 0 0 3 5 0 0 0
4.4 3 0 0 0 0 1 5 2 0
5 2 1 0 5 0 0 0
1 6 0 0 0
f ab te  )! : N um b er  of c a n :  found posit ive for BaciHus and
C to stridium.
Storage time
Con servat ion temperature in °C
- )  8 + 5 + 10 + 35 + 50
2 ----- ------- 8 : 10 8 : 10
X6: 10  ( 4 : 1 0 )
4 ------ 8 ; 10 io : io
X
4 : 10  ( 1 0 . 1 0 )
Numbers mentioned in brackets are for  CLostridium.
Tabte 12 ! R e s u t t s  of b i o c h e m i c a t  t e s t s  o n  t e n  d i f f e r e n t  c o t o n i e s  
of C t o s t r i d i u m .
Te s t s Cot oni es
) 2 3 4 5 6 7 8 9  10
Amy t a s e  Act ivi ty - +
W^S P r o d u c t i o n + + + + + + + + + +
[ndote P r o d u c t i o n -
Réduct i on of  N i t r a t e s + - + + + + - + + +
Fe r me nt a t i o n  R é a c t i o n s
G t u c o s e + + - + + - + + +
L a c t o s e
Manni t o t
S a c c h a r o s e



Canned mangrove crab (<i>Scylla serrata</i>): a product with limited shelf life

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