A microbiological study of some microwave cooked foods

Document Type : Original Articles


A total of 150 fresh samples of fish, beef and chicken (50 samples for each} were collected from dijf erent retail stores in Alexandria Samples were examined microbiolog­ ically in its fresh state (prior cooking) and after microwave cooking (immed iately and after 6 hours of cooking) . Results indicated that the mean (log CFU Igrn) total aer­ obic bacterial counts of uncooked fish, beef and chicken samples were as follows: 5.700 log l O. 5.627 log l O, 5.863 log l O; respectivel y. However, the total aerobic bact eri­ al cou11 ts of post microwave cooked fish, beef and chicken samples (immediatel y qfl .cr cooki11g a11d after 6 hours cooking) were 3.651 log l O, 3.066 log l O, 2.978 log l O w1d 4.870 log l O, 5.011 logl O, 4.159 log l O for immed iately and after 6 hours; respectivel y with a significant dijference between total aerobic bacterial counts of uncooked n11d post microwave cooked samples. Moreover, in fish samples, there was a decrease i11 the percent of bacterial survival from 100% for uncooked to 14% for imfriediatel y and 6%for after 6 hours after cooking , respectively.The percent of bacterial survival q{ beef and chicken samples was decreased from 100% of uncooked samples to I 4%. 10% i11 beef and 20%, 896 in chicken samples for immed iately after cooking and after 6 hours cooking. It was also reported that the mean values (mean log cfu/ gm) of total yeast and mould counts of fish samples were 4.995 log 10for uncooked , 3.075 log 10for im­ mediatel y qfter cooking and 4.100 log l O for after 6 hours cooki11g , with a sig11(J kw1l d ff[crence between total yeast and mould counts of them. The percent of survival was decreased from f/8% in uncooked f!S h samples to 28% and 16% in post microwave cooked samples (immediately and after 6 hours cooking). Concerning beef samples. the mean total yeast and mould counts were found in uncooked (5.327 log 1 OJ followed by ajler 6 hours cooking (4.279 log l O) and immediately after cooking (2.945 log l OJ. M oreo­ ver, 24% of beef samples showed yeast, mould survival. immediatey after cooking but q/ler 6 hours cooking. 22% of beef samples showed yeast and mould survival. In ca se nf chiclcen samples, the mean levels of total yeast and mould counts


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