الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This investigation aims to the possibility of utilizing the
bolti fish which obtained from High Dam Lake specially large
size and underutilized for manufacturing imitated shellfish
product and compared with natural shell fish and also, aims to
study the possibility of gamma irradiation at doses 1, 3, and 5
kGy for keeping the quality of imitated fish product during cold
storage. Therefore whole fish boIti were obtained from Misr
Aswan Company. The whole fish were dressed and minced. The
obtained minced fish was washed three times with sodium
bicarbonate (0.2%), distilled water and sodium chloride solution
(0.15%). The cryoprotectants ingredient (sorbitol, sucrose and
tripoliphosphate) was added to washed minced fish for
producing intermediate product (surimi). The final product
(imitated fish) was manufactured by adding egg white, starch,
corn oil, natural color and flavor of shrimp and crab according to
special formula for shrimp and crab. The imitated shrimp sample
were irradiated at doses 1, 3 and 5 kGy and cold stored.
The obtained results could summarized as following:
A- Yield of bolti fish: -
The results indicated that the big size of fish gave high
yield as compared with small size and the average of the yield
(dressing percentage) ofbolti fish was 42.8 %.
B- Effect of washing on chemical composition, quality
attributes and microbiological load of bolti mince: -
l-Washing process caused an increase in moisture content
of fish mince to 81.1 % after third washing and fat and ash
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content were reduced from 17.66 and 5.25 % (on dry weight
basis) to 8.25 and 3.12 % (on dry weight basis) respectively.
2-Washing steps increased protein content and salt
extractable protein from 75.53 % (on dry weight basis) and 45.26
”Y 0 to 88.25 (on dry weight basis) and 88 %respectively.
3-TVN and TBA were decreased after washing steps from
9.93 mg / 100g sample and 0.88 mg / kg to 3.12 mg / 100g
sample and 0.72 mg / kg respectively, after washing.
4-WHC was increased after washing steps from 74.930 A
to 82.26 % on the other hand pH was slightly decreased after
washing process from 6.78 to 6.57.
5-Washing reduced the Total bacterial count,
Psychrophilic bacteria, yeast and mold counts.
6-Washing process reduced the mineral contents (Ca, P,
Na, K and bp) of boIti mince.
C- Sensory evaluation for choosing the best flavor
concentration of shrimp and crab :-
I-Results showed that the best concentration of flavors
could be used in imitated shrimp were 1 and 2 gm / kg from
shrimp Aspin flavor and American flavor respectively.
2-The results indicated that the best concentration of
American crab flavor in imitated crab was 2 gm / kg.
D- Yield of surimi:-
Yield of surimi was 42.38% and washed mince was
32.28%.
E- Chemical composition of natural and imitated shrimp
and crab:
1- Moisture content of natural and imitated shrimp and
crab were 74.86, 77,81, 78.02 and 79.33 % respectively.
2-Results concluded that protein, fat, ash and carbohydrate
contents of natural and imitated shrimp were 84.76, 47.68,86.71
and 55.640 A; 8.47, 7.66, 4.69 and 4.89 %; 4.73, 6.13, 8.32 and
11.22 %; 2.03, 38.53, 0.27, 28.25 % ( on dry weight basis),
respectively.
F- Effect of cooking on the quality attributes of natural
and imitated shrimp and crab:-
I-Salt extractable protein of natural and imitated shrimp
were 32.7 and 53.4 for unheated sample and were reduced by
heat treatment to 25.8 and 47.4 % respectively.
2-Similarly, salt extractable protein of natural and imitated
crab was decreased after heating to 29.10 and 39.49 %
respectively.
3- Heating process slightly reduced TVN of natural and
imitated shrimp from 24.6 and 2.11 mg/lOOgto 24.2 and 1.69 and
mg/ 100grespectively.
4- Similarly, heating process slightly reduced TVN of
natural and imitated crab from 22.30 and 1.83 mg/100g to 22.0
and 1.45 mg/lOOgrespectively.
5- Heating process caused slightly increased the TBA and
pH of natural and imitated shrimp and crab.
6-Heating process reduced WHC of imitated shrimp and
crab.
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G- Effect of cooking (heating process) on microbiological
parameters of natural and imitated shrimp and crab:-
Heating process decreased total bacterial count,
psychrophilic bacteria, mold and yeast of natural and imitated
crab.
H- Effect of irradiation by different doses on chemical
composition and quality attributes of imitated shrimp
and during cold storage period:-
1-Results indicated that moisture, protein and fat contents
of imitated shrimp were 74.69,47.09 and 7.74 % (on dry weight
basis) respectively and the chemical composition of samples
were not change after irradiation where as slightly decreased
during cold storage.
2- Irradiation with doses 1, 3 and 5 kGy caused slightly
increase in TBA after irradiation and there was gradual increase
in TBA during cold storage period.
3- WHC was slightly increased after irradiation and there
was a gradual decrease in WHC.
4- pH of imitated shrimp was slightly increase after
irradiation and gradual decrease during cold storage period.
5- Salt extractable protein was not affect after irradiation
and during cold storage period.
6- Irradiation treatment by doses 1, 3 and 5 kGy caused
slightly increase in TVN and there was a gradual increase during
cold storage.
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J- Microbiological analysis of imitated shrimp during
cold storage:
1-Total bacterial count, psychrophilic bacteria, yeast and
mold of imitated shrimp was 2xIO 2, IxI02, <10 and <10 cfu /g
respectively.
2- Irradiation treatment caused a significant decrease in
total bacterial count, psychrophilic bacteria, mold and yeast and
this decrement was increased as increase in dose.
3- Total bacterial count was increased during cold storage
in all treatment.
4- Psychrophilic bacteria of unirradiated samples and
eradiated with 1 kGy was increased during cold storage. While
there were no growth in the initial period of cold storage but
there was a growth at the end of cold storage in irradiated
imitated shrimp with doses 3 and 5 kGy.
5- cold storage period caused increase in yeast of
unirradiated imitated shrimp but irradiated imitated shrimp did
not show any growth at the initial period of cold storage and
there was a gradual growth at the end of cold storage.
6- Mold growth was detected at the end of cold storage
period of all treatment.
K- Sensory evaluation of imitated shrimp during storage
period:-
Results indicated that irradiation process did not affect in
the appearance of imitated shrimp. While mold growth started at
the surface of unirradiated samples and the panelists rejected
these samples.
It could be concluded that using of boIti fish as a raw
material for processing of imitated fish (crab and shrimp), also
using of shrimp flavor (Aspin) at 1 gm / kg was the best
treatment. In addition it could be concluded that gamma
irradiation at doses of 3 kGy was the best treatment under
investigation for extending the shelf life of imitated shrimp to 16
weeks which cold stored without a deleterious effects on their
chemical, microbiological and sensory properties compared to 7
weeks for control sample.