الفهرس 
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Abstract
A grand total of 300 beef meat samples(taken from 60 original samples)were taken from top side of the same carcass; divided into 4 parts (15 samples for each) and each sample was 200 g weight). The 1St part remained uncooked (raw) while the other 3 parts were subjected to different methods of cooking, the 1st part was boiled, 2nd part was fried and the 3rd part was roasted and then all the samples were kept in domestic refrigerator at chill temperature 4 ° C for 4 days. The whole samples were examined organoleptically, chemically and bacteriologically during the whole storage period (from zero day until the 4th day of storage period) for detection of spoilage.
1. Sensory evaluation
1.1 Color: The mean values of color of fresh uncooked meat at zero, 1st,
2nd, 3rd and 4th days of storage at chill temperature 4 ° C were 9.3, 7.7,
5, 3.8 and 0.3, respectively. The mean values of color of boiled meat
, d 3rd 1st 2n, 3r and • at zero, 4 days of storage at chill temperature 4 ° C
were 9.4, 8.5, 4.8, 3.2 and 0.3, respectively. The mean values of color of fried meat at zero, 1st, -.rid 3rd and 4th days of storage at chill temperature 4 ° C were 9.6, 6.5, 3.5, 1.7 and 0.3 , respectively. The
d an • • 4th mean values of color of roasted meat at zero 1st, 2nd, 3r days of
storage at chill temperature 4 ° C were 9.5, 7.2, 4.8, 1 and 0.3, respectively.
1.2 Flavor: The mean value of aroma of fresh uncooked meat at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C were 9.5, 7.5, 5.5, 3.2 and 1.2, respectively. The mean values of aroma of boiled meat at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C were 9, 7.7, 4.2, 3 and 1.7, respectively. The mean values of aroma of fried meat at zero, 15d 3r-- and 4th days of storage at chill temperature 4 ° C were 9.5, 6.3, 3.3, 1.2 and 0.7, respectively. The mean values of aroma of roasted meat at zero l’, 2nd 3rd and 4’h days of storage at chill temperature 4 ° C were 9.5, 6.7, 3.7, 1.2 and 0.8, respectively.
1.3 Texture: The mean values of texture of fresh uncooked meat at zero, ist, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C were 9, 7.8, 6.3, 3.3 and 0.8, respectively. The mean values of texture of boiled meat at zero, 1st 2nd, 3rd .3 and 4th days of storage at chill temperature 4 ° C were 9.3, 7.8, 4, 2.8 and 0.3, respectively. The mean values of texture of fried meat at zero, 1st, end 3rd and 4th days of storage at chill temperature 4 C were 9.7, 6.7, 3.2, 1.3 and 0.5 , respectively. The mean values of texture of roasted meat at zero 15, 2 3rd and 4th days of storage at chill temperature 4 ° C were 9.5, 6, 3.2, 1.7 and 0.5, respectively.
1.4 Overall acceptance: The mean values of overall acceptance of fresh uncooked meat at zero, 1st, 2nd, 2 3rd and 4th days of storage at chill temperature 4 ° C were 27.8, 23, 16.8, 10.3 and 2.3, respectively. The mean values of overall acceptance of boiled meat at zero, and 4th days of storage at chill temperature 4 C were 25.7, 24, 13, 9 and 2.3, respectively. The mean values of overall acceptance of fried meat at zero, 1st, 2nd, 3rd and 4th days of storage at chi II temperature 4 ° C were 28.8, 19.5, 10, 4.2 and 1.5, respectively. The mean values of overall acceptance of roasted meat at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C were 28.5, 19.9, 11.7, 3.9 and 1.6, respectively 2. Bacteriological profile .
2.1 APC: In fresh uncooked meat, the mean values of APC were 1.3x105, 7x105, 6x107, 3x101° and 6.3x1012 at zero, 1st, 2”, 3`d and 4th days of storage at chill temperature 4 C, respectively. In boiled meat they were 1.3 x103, 8 x105, 3.3 x106, 1.3 x108and 5.7 xl Om, respectively. In fried meat the mean APC values were 1.6 x103, 5.7 x105, 4.7 x107,
, 2 5.3 x109 and 9 x1011 at zero, 1,tnd, 3rd and 4th days of storage at chill temperature 4 C, respectively. In roasted meat, the mean APC values were 5 x102 at zero day, 7.3 x103 at the 1st day of storage, 1.6 x106 at the 2nd day, 1.7 x107 at the 3rd day of storage and 5.1 x109 at the 4th day of storage (at chill temperature 4 C).
2.2 Psychrotrophic count: In fresh uncooked meat, at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 C, the mean psychrotrophic counts were 3 x103, 5 x 105, 5 x107, 6.3 x109 and 4.6 x1012, respectively. In boiled meat, the mean psychrotrophic counts were 4.7 x103 at zero day, 2.3 x106 at the 1st day, 1.3 x108 at the 2” day, 7.7 x1011 at the 3rd day and 3 x1013 at the 4th day of storage at 4 C, respectively. In fried meat, the mean psychrotrophic counts were 6.7 x103, 5.7 x105, 3.1 x108, 1.9 x101° and 2.3 x10’2 at zero, 1st 2nd, 3rd and 4th days of storage at chill temperature 4 C, respectively. In roasted meat, the mean psychrotrophic counts were 6.7 x102, 2.3 x104, 3.7 x106, 7 x108 and 9 x101’ at zero, 1st, 2”, 3rd and 4’h days of storage at chill temperature 4 C, respectively.
2.3 S. aureus count: In fresh uncooked meat, the mean S. aureus counts were 6.7 x10, 1.6 x103, 4.3 x103, 2 x104 and 1.7 xlOs at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 `) C, respectively. In boiled meat, they were,< 102, 102, 3.3x102, 1.6x103 and 9x103 at zero, ist, 2nd, 3rd
and 4th days of storage at chill temperature 4 C, respectively. In fried meat, the mean S. aureus counts were, <102, <102, 2.3x 102, 9.7x102 and 7x 103 at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C, respectively. In roasted meat, the mean S. aureus counts were,< 102, 3.3x10, 3.7x 102, 2.7x103 and , , 1st 2,d 3rd an I A th 8.7x103 at zero, and 4 days of storage at chill temperature
4 ° C, respectively.
2.4 Coliforms count: In fresh uncooked meat, the mean coliforms counts
,
at zero, 1st, 2ndrd and 4th days of storage at chill temperature 4 ° C, were 4.7, 16.7, 83.3, 206.7 and 700, respectively. In boiled meat they were <3, 4.3, 19, 34.3, and 83.3, respectively. In fried meat, the mean 3rd coliforms counts at zero, 1st, Znd, 3r- and 4th days of storage at chill temperature 4 ° C, were <3, 3.7, 9.7, 19.7, and 28.7, respectively. In roasted meat, the mean coliforms counts at zero,
1’, 3rd and 4th
days of storage at chill temperature 4 ° C, were <3, 2, 9.7, 21.7, and 34.3, respectively.
2.5 E. coli : Showed positive results in fresh uncooked meat, in boiled meat, E. coli could not be detected at zero and 1St day of storage at chill temperature 4 ° C, but they were detected at 3rd and 4th days of storage at chill temperature 4 ° C. In fried meat, E. coil were absent during the 1St three days of the experimental storage period at chill temperature 4 ° C and they were detected only at the 4th day of storage at chill temperature 4 ° C. while in roasted meat, E. coli were completely absent during the whole experimental storage period at chill temperature 4°C.E.coli serotypes isolates were 0124:K72(B17),055:K59(B5),026:K60(B6) and 01 19:K 69(B 19).
2.6 Salmonella: Salmonella could not be detected either in the examined fresh uncooked or cooked meat samples regardless the method of
cooking. 3. Chemical profile:
3.1 pH: The mean values of pH of fresh uncooked meat during the whole storage period at chill temperature 4 ° C were 5.65, 6.19, 6.3, 7.14 and 7.61 at zero, 1st, 2nd, 3rd and 4th days of storage period, respectively. In boiled meat, the mean pH value at zero day was 5.86 and 6.07, 6.65, 7.33 and 7.7 at the 1st, 2nd, 3rd an • 4th d 4 days of storage at chill
temperature 4 ° C, respectively. In fried meat, the mean pH values were 5.73, 6.03, 6.7, 7.27 and 7.47 at zero, 1st, 2nd, 3rd and 4th days of storage period at chill temperature 4 ° C, respectively. In roasted meat, the mean pH values were 5.84, 6.01, 6.78, 7.3 and 7.93 at zero,
1st, 2nd,
and 4th days of storage period at chill temperature 4 ° C,
respectively.
3.2 TVB-N: In fresh uncooked meat, the mean value of TVB-N at zero day was 8.33 mg/100g. In the 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C,they were 17, 24.67, 36.33 and 48.33 mg/100g, respectively. In boiled meat, the mean TVB-N values at zero, 1st, 2nd, 3rd and 4th days of storage at chill temperature 4 ° C, were 8, 15.33, 24.33, 34.67 and 39.67 mg/100g, respectively. In fried meat, the mean TVB-N values were 7.67 mg/100g, at zero day, 17.33 mg/100g at the 1st day, 26.67 mg/100g at the 2nd day, 35.33 mg/100g, at the 3I’d day and 42.67 mg/100g, at the 4th day of storage period at chill temperature 4 ° C. In roasted meat, the mean TVB-N values were 8.67, 15.67, 24.67, 33.67 and 44.33 mg/100g, at zero, 1st, 2”1, 3rd and 4th days of storage at chill temperature 4 C, respectively.
3.3 TBA: In fresh uncooked meat, the mean TBA values were 0.08, 1st, 0.223, 0.77, 1.333 and 1.587 mg MD/kg at zero, 1st2 3rd and 4th days of storage at chill temperature 4 C, respectively. In boiled meat They were 0.143, 0.207, 0.56, 0.75 and 0.99 mg MD/kg, respectively. In fried meat, the mean TBA values were 0.13, 0.237, 0.54, 0,943 and 1.533 mg MD/kg, at zero, 1st, 2nd, 3rd and • th
a 4th days of storage at chill
temperature 4 ° C, respectively. In roasted meat, the TBA values at
zero, 1st, 2nd, 3rd and • th
a 4th days of storage at chill temperature 4 ° C,
were 0.157, 0.227, 0.473, 0.843 and 1.233 mg MD/kg, respectively.
from the obtained results, one can conclude that organoleptic study is important because once meat be rejected organoleptically, the incipient spoilage occur. The present study reviewed the bacteriological status of fresh uncooked and cooked chilled meat as the role of bacteria on their spoilage at different stages of storage.
The most important quick, simple and reliable chemical tests for measuring the incipient and complete spoilage of fresh and cooked meat were pH, TVB-N and TBA.
This study considered the presence of correlations between organoleptic tests, microbiological examination and chemical examination used for detection of the spoilage of uncooked and cooked meat by different cooking methods.