الفهرس 
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Abstract
This study was conducted to prepare fish burger by replacing
minced tilapia fish with 10, 15, 20 and 25% of mashed pumpkin or
mashed potato. Canned fish luncheon was prepared by replacing
minced tilapia fish with 20, 25, 30 and 35% of beef fat and stored at
room temperature for 6 months. Extruded products were also prepared
from yellow corn grits (90%) and corn starch (10%). Yellow corn grits
was replaced by dried carp fish and dried after fried carp fish with 5,
10 and 15%, then packaged in polypropylene bags and stored at room
temperature for 3 months. The chemical composition, chemical and
physical quality characteristics, color, texture, microbiological
analysis, mercury, cadmium and sensory properties of prepared
products were evaluated.
The obtained results can be summarized as follows:
6.1. Tilapia fish burger:
6.1.1. Proximate composition of raw materials:
Minced tilapia fish had lower moisture (78.26%) and higher
protein (18.59%), fat (1.97%) and ash (1.18%) contents than mashed
pumpkin and mashed potato. Mashed pumpkin had higher protein
(1.89%) and ash (1.01%) contents than mashed potato. Mashed potato
had higher carbohydrate content (16.52%) than mashed pumpkin (on
wet weight basis).
6.1.2. Proximate composition and energy:
Fish burgers formulated with different replacement levels of
mashed pumpkin or mashed potato had higher moisture (68.19-69.07%)
and carbohydrate (10.86-12.97%) contents and lower crude protein
(13.82-15.65%), crude fat (2.13-2.31%), total ash (2.49-2.69%) and
energy values (124.45-128.17 kcal/100g) than control fish burger.
Moisture content was highly reduced by cooking process. Crude
protein, crude fat, total ash and carbohydrates contents were increased
by cooking process.
6.1.3. Chemical quality characteristics and pH value:
Fish burgers formulated with mashed pumpkin or mashed potato
had lower TVN values (9.45-11.20 mg/100g) than control (12.08
mg/100g) at any replacement levels. There are no differences in the
TMA (up to 20%) and TBA (up to 15%) values between control and
fish burgers formulated with mashed pumpkin or mashed potato.
However, TMA, TBA values at higher replacement levels were lower
than control fish burger. Neither replacer type nor cooking process
affected TVN, TMA and TBA values except TVN values which
decreased by cooking process. The pH values were not affected by
replacer level, replacer type and cooking process.
6.1.4. Cooking characteristics:
Cooking yield was decreased by increasing mashed pumpkin or
mashed potato replacement levels. There was no difference in moisture
retention value between control and fish burgers formulated with
mashed pumpkin or mashed potato up to 15% replacement level.
However at higher replacement levels, moisture retention values
(73.62-75.11%) were lower than control fish burger (76.91%). Fish
burger formulated with different replacement levels of mashed
pumpkin or mashed potato had higher fat retention values (167.11-
173.06%) than control fish burger (162.59%). There was no difference
in shrinkage value between control and fish burger formulated with
20% mashed pumpkin or mashed potato. At 25% replacement level,
shrinkage value (7.96%) was higher than control fish burger (7.64%).
Fish burgers formulated with different replacement levels of mashed
pumpkin or mashed potato had higher juiciness values (3.84-4.84%) than
control fish burger (2.61%) at any replacement levels. Cooking yield,
moisture retention and juiciness were not significantly affected by
replacer type.
6.1.5. Water holding capacity and plasticity:
Fish burger formulated up to 20% mashed pumpkin or mashed
potato had higher water holding capacity (2.77-3.29 cm²/0.3g) than
control fish burger (2.37 cm²/0.3g). However there was no difference in
water holding capacity value between control and fish burger
formulated with 25% mashed pumpkin or mashed potato. Plasticity was
not affected by replacement levels and types. Water holding capacity
and plasticity were reduced by cooking process.
6.1.6. Color measurement:
There were no difference in the Lightness (L*) values between
control and fish burgers formulated with mashed pumpkin or mashed
potato up to 15% replacement level. However at higher replacement
levels, Lightness (L*) values (39.94 42.71) were lower than control
fish burger (48.26). Fish burgers formulated with mashed pumpkin or
mashed potato up to 20% replacement levels had higher redness (a*)
values (4.91 5.32) than the control (3.84). However at 25%
replacement level, redness (a*) value was similar to control fish
burger. Yellowness (b*) values were not affected by replacement
levels. Lightness (L*) and redness (a*) values were not affected by
replacement types. Fish burger formulated with mashed pumpkin had
higher yellowness (b*) values (19.71) than fish burger formulated with
mashed potato (13.97). Hue angle values were not affected by
replacement levels and types.
6.1.7. Texture profile:
Hardness values were increased with replacement levels of mashed
pumpkin or mashed potato with the exception of 10% replacement level
which increased but not significant. Fish burger formulated with mashed
potato had higher hardness (18.55) than fish burger formulated with
mashed pumpkin (13.89). Cohesiveness and springiness values were not
affected by replacement levels and types.
6.1.8. Microbiological analysis:
Fish burgers formulated with different replacement levels of
mashed pumpkin or mashed potato had lower total bacterial count,
proteolytic bacteria, lipolytic bacteria, psychrophilic bacteria and total
yeast and mold counts than control fish burger. All microbial contents
were decreased by increasing mashed pumpkin or mashed potato
replacement levels. Cooking process reduced total bacterial counts in fish
burger from 15-47×103 to 12-44×102 cfu/g of sample.
6.1.9. Mercury and cadmium:
Mercury was not detected in all fish burger samples. Cadmium
content in fish burger samples ranged from 0.0001 to 0.00481 mg/kg.
The Mercury and Cadmium contents in cooked fish burgers were
below the permissible limits.
6.1.10. Sensory properties:
Fish burgers formulated with 15 and 20% of mashed pumpkin or
mashed potato had higher rating scores ranged between 8 and 8.25 of
all sensory properties under study and described as like very much.
Control fish burger and burgers formulated with 10 and 25% mashed
pumpkin or mashed potato had rating scores ranged between 7.2 (like
moderately) and 8.20 (like very much) of all sensory properties under
study.
6.2. Tilapia fish luncheon:
6.2.1. Proximate composition of raw materials:
Tilapia fish had higher moisture (78.26%), crude protein (18.59%)
and total ash (1.18%) contents and lower crude fat (1.97%) than beef fat.
Minced tilapia fish and beef fat had zero carbohydrates content.
6.2.2. Proximate composition and energy:
Control fish luncheon had higher moisture (72.75%), crude protein
(14.24%) and total ash (0.98%) and lower crude fat (2.03%) and energy
(115.22 kcal/100g) than fish luncheon formulated with different
replacement levels of beef fat. Moisture and crude protein contents of
fish luncheon formulated with different replacement levels of beef fat
were decreased by increasing beef fat replacement levels. However,
crude fat and energy values had opposite trend. Fish luncheon formulated
with different replacement levels of beef fat had a lower total ash than
control fish luncheon. Moisture and energy values of canned fish
luncheon were decreased by increasing the storage period.
6.2.3. Chemical quality characteristics and pH value:
The TVN and TMA values of fish luncheon were decreased by
increasing beef fat replacement levels. The TVN and TMA values were
increased by increasing storage period. The TBA values of fish luncheon
were increased by increasing beef fat replacement levels and storage
period. The pH values were not affected by beef fat replacement level but
they increased during storage period. The TVN, TMA and TBA values
of canned fish luncheon were within the acceptable limits.
6.2.4. Gross weight, net weight, juiciness, water holding capacity
and plasticity:
Gross weight, net weight and plasticity of fish luncheon were
not affected by replacement levels of beef fat and storage period.
Juiciness of fish luncheon formulated with 35% replacement level of
beef fat (23.62%) was higher than control fish luncheon (18.74%) and
similar to other luncheon treatments. Juiciness was increased during
storage period. Water holding capacity was decreased by 25%
replacement level of beef fat and similar to 20% and 30% replacement
levels of beef fat. However, water holding capacity was increased by
35% replacement level of beef fat than control fish luncheon. Water
holding capacity was also increased by storage period up to 2 months.
However at 4 and 6 months of storage, water holding capacity was
similar to zero time.
6.2.5. Color measurement:
Lightness (L*) value of control fish luncheon (38.42) was lower
than fish luncheon formulated with different replacement level of beef
fat. Redness (a*) value of control fish luncheon (2.47) was higher than
fish luncheon formulated with different replacement level of beef fat.
Yellowness (b*) value of control fish luncheon was similar to fish
luncheon formulated with beef fat up to 30% replacement level. However
at 35% replacement level, yellowness (b*) value was higher than control
fish luncheon. Hue angle of control fish luncheon was lower than fish
luncheon formulated with 25-35% replacement level of beef fat and
similar to fish luncheon formulated with 20% replacement level.
Lightness (L*), redness (a*) and yellowness (b*) values were decreased
during storage period. However, hue angle was increased during storage
period.
6.2.6. Texture profile:
Hardness of fish luncheon formulated with beef fat up to 30%
replacement levels was similar to control fish luncheon. At 35%
replacement level, hardness was lower than control fish luncheon and
other treatments. Hardness of fish luncheon was reduced during storage
period. Cohesiveness was not affected by the replacement levels of beef
fat but was reduced during storage period. Springiness of fish luncheon
was not affected by replacement levels of beef fat and storage period.
6.2.7. Microbiological analysis:
Fish luncheon formulated with different replacement levels of beef
fat had lower total bacterial count and proteolytic bacteria and higher
lipolytic bacteria than control fish luncheon. Total bacterial count of fish
luncheon did not detect at zero time and increased during storage period
(2-6 months) from 1×102 to 9.5×102 cfu/g. Proteolytic bacteria and
lipolytic bacteria counts of fish luncheon did not detect up to 2 months of
storage. However at 4 and 6 months of storage, proteolytic bacteria and
lipolytic bacteria counts ranged from 5×10 to 11×10 and 5×10 to
13.5×10 cfu /g, respectively. Total yeast and mold of fish luncheon did
not detect during storage period.
6.2.8. Mercury and cadmium:
Mercury content did not detect in all fish luncheon samples.
Cadmium content in fish luncheon samples at zero time and 6 months of
storage ranged from 0.00125 to 0.0082 and 0.012 to 0.097 mg/kg,
respectively.
6.2.9. Sensory properties:
Fish luncheon formulated with 25 and 30% replacement levels of
beef fat had higher taste, odor, texture and overall acceptability than
control fish luncheon. However, their color was similar to control fish
luncheon. Fish luncheon formulated with 25 and 30% replacement levels
of beef fat had higher scores of sensory properties than fish luncheon
formulated with 35% replacement levels except for odor which was
similar to fish luncheon formulated with 35% replacement levels. All
sensory properties of fish luncheon were reduced by storage period.
6.3. Extruded corn products:
6.3.1. Proximate composition of raw materials:
Fresh carp fish had higher moisture than other raw materials and
lower protein, fat, ash and energy contents than dried carp fish and dried
carp fish after frying. Dried carp fish and dried carp fish after frying
had lower moisture content and higher protein, fat, ash and energy
contents than yellow corn grits and corn starch. However, yellow corn
grits and corn starch had higher carbohydrate content than other raw
materials. Yellow corn grits had higher moisture, protein, fat and ash
contents and lower carbohydrate and energy contents than corn starch.
Fresh carp fish and dried carp fish had not carbohydrates content.
6.3.2. Proximate composition and energy of extruded corn
products:
Extruded corn products formulated with different replacement
levels of carp fish had higher moisture, crude protein, crude fat and
energy and lower carbohydrate than control sample which formulated
with 90% yellow corn grits and 10% corn starch. Total ash content of
extruded corn products formulated with 10 and 15% replacement levels
of carp fish were higher than control however at 5% replacement level of
carp fish, total ash was similar to control. There were no differences in
moisture, total ash and carbohydrates between extruded corn products
formulated with dried carp fish and those formulated with dried carp fish
after frying. However, extruded corn products formulated with dried carp
fish had higher crude protein and lower crude fat and energy than those
formulated with dried carp fish after frying. Proximate composition and
energy of extruded corn products were not affected by storage period.
6.3.3. Chemical quality characteristics and pH value of extruded
corn products:
The TVN, TMA and TBA values of extruded corn products
formulated with different replacement levels of carp fish were increased
by increasing replacement levels of carp fish. Extruded corn products
formulated with dried carp fish had higher TVN and TMA and lower
TBA values than those formulated with dried carp fish after frying. The
TVN, TMA and TBA values of extruded corn products formulated with
different replacement levels of carp fish were increased by increasing
storage period. However, pH values of extruded corn products were not
affected by different replacement levels and types of carp fish and
storage period.
6.3.4. Physical properties of extruded corn products:
Expansion ratio and water solubility index of extruded corn
products were decreased and bulk density, shear force and water
absorption index increased by increasing the replacement levels of carp
fish. Extruded corn products formulated with dried carp fish had higher
expansion ratio, water absorption index and water solubility index and
lower bulk density and shear force than those formulated with dried carp
fish after frying. Physical properties of extruded corn products were not
affected by storage period.
6.3.5. Microbiological analysis of extruded corn products:
Total bacterial count of extruded corn products was reduced from
2.9×102 to 1.8×102 cfu/g by increasing replacement levels of carp fish.
Dried carp fish after frying was more affected than dried carp fish in
reducing total bacterial count. Total bacterial count of extruded corn
products was increased by increasing the storage period. Proteolytic
bacteria count, lipolytic bacteria count and total yeast and mold of
extruded corn products did not detect in all samples.
6.3.6. Sensory properties of extruded corn products:
Taste of extruded corn products was increased by increasing
replacement levels of carp fish. However, color, crispiness, chewiness
and pore distribution had opposite trend. Extruded corn formulated with
5 and 10% carp fish had higher surface characteristics than extruded corn
control. No significant difference was observed in surface characteristics
between extruded corn control and extruded corn formulated with15%
carp fish. No significant difference was found in overall acceptability
among extruded corn products. On the other hand, extruded corn
formulated with dried carp fish after frying had higher taste, crispiness,
chewiness, surface characteristics and overall acceptability and lower
pore distribution scores than extruded corn formulated with dried carp
fish. The color was similar in both products. Color, crispiness, pore
distribution and surface characteristics of extruded corn products were
decreased by increasing storage period. Taste, chewiness and overall
acceptability of extruded corn products did not differ up one month of
storage followed by decrease in their scores up to the end of storage
period.