الفهرس 
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Abstract
A grand total of 100 random local chilled and imported frozen meat samples (50 0f each) were collected from local supermarkets and retail shops in Cairo governorate. The imported meat samples were collected from raw frozen imported meat stored at temperature -18°C which were collected during its claimed shelf life time, while the local meat samples were collected from raw local chilled meat stored at 4°C, collected during the claimed shelf life time then all samples were transferred directly to the laboratory in an ice-box under complete aseptic conditions without any delay. Then they were subjected to different examinations to evaluate sensory organoleptic, chemical and microbiological quality.
The values of sensory profile of local chilled meat samples ranged between 40% from grade (1) to 10% from grade (5), 44% from grade (1) to 4% from grade (5), 60% from grade (1) to 2% from grade (5) and 50% from grade (1) to 0% from grade (5) for tenderness, juiciness, flavor and overall acceptability respectively, while the results of imported frozen samples ranged between 14% from grade (1) to 18% from grade (5), 16% from grade (1) to 18% from grade (5), 30% from grade (1) to 30% from grade (5) and 10% from grade (1) to 10% from grade (5) for tenderness, juiciness, flavor and overall acceptability respectively.
Microbiological examination of beef samples revealed that Aerobic plate count in the examined local chilled meat samples were between 1.1×106 cfu/g. and 4.4 ×107 cfu/g. with an average of 4.1×107± 0.2×106 cfu/g. while the results of examined imported frozen samples were ranged between 2.7×107 cfu/g. to 5.3 ×108 cfu/g. with an average of 2.9×107± 0.2 ×106 cfu/g. coliforms count for local chilled samples were ranged from 1×103 cfu/g. to 12.4×103 cfu/g. with an average of 4.2x103 ± 0.3×102 cfu/g., while imported frozen samples ranged between 6×102 cfu/g. and 11.0×103 cfu/g. with an average of 7.1x103 ± 0.2×102 cfu/g. E. coli has been detected in 4% of local chilled samples and 2% of imported frozen samples. E. coli O55: H7 has been detected only in 2% of local chilled meat samples and E. coli O125: H18 was detected in 2% of local chilled meat samples, while E.coli O114: H21 were detected in 2% of imported frozen meat samples.Salmonella spp. has been detected in 4% of local chilled samples while all imported frozen samples were free. Shigella spp. was failed to be isolated from any of the examined local chilled or imported frozen meat samples. all isolated Salmonella based on their antigenic structure were S. Enteritidis. The results of yeast and mold count for local chilled samples were ranged from 5×102 cfu/g. to 3.5×103cfu/g. with average of 1.3x103 ± 0.2×102cfu/g., while frozen samples ranged between 2×102cfu/g. and 3×103cfu/g. with an average of 1.2x103 ± 0.2×102 cfu/g . The incidence of isolated molds and yeast genera in the examined chilled local and frozen imported meat samples were Asperigillus ocharceus, Asperigillus fumigatous and Rhizopous spp. In 30%, 20% and 50% of local chilled meat samples, respectively. While, they were 0%, 66.6% and 33,4% in imported frozen meat samples, respectively.from the overall results of microbiological examination, we can conclude that both local chilled and imported frozen meat are considered as a significant source of bacteriological public health hazard related to some food poisoning bacteria.There is no significant difference between local chilled and imported frozen meat in terms of acceptance based on APC and total coliform contamination. Both local chilled and imported frozen meat showed a percentage of E. coli and yeast and mold contamination. However, frozen meat samples were free of Salmonella spp. Both local chilled and imported frozen meat samples did not show any risk from Shigella spp. contamination.
Chemical examination of beef samples revealed that the mean values of pH, TVB/N (mg%) and TBA (mg/Kg) were 5.77 ± 0.32, 11.9±1.63 & 0.58± 0.10 for chilled local meat samples, respectively, while they were 6.6 ± 0.12, 21.5 ± 1.95 & 0.95 ± 0.11 for imported frozen samples respectively .Overall chemical results which obtained were considered as important meat quality indicators.According to Egyptian standard specifications, 30% of chilled meat samples and 60 % of frozen meat were unfit for human consumption due to their unaccepted PH value.While, 10% of local meat samples and 40 % of frozen meat samples were unacceptable for human consumption due to high TVB/N content according to Egyptian standard specifications.The results of TBA showed that 20% of local meat samples and 50 % of frozen meat samples were unacceptable for human consumption due to their high TBA value according to Egyptian standard specifications.Finally, the significance of such meat quality indices and some recommendations for control of those quality factors were discussed.