KEEPING THE QUALITY OF READY-TO-EAT MEALS BY GAMMA IRRADIATION

Abstract

The possibility of using gamma irradiation for keeping the quality of ready-to­ eat meals was studied. The prepared meals (included cooked meat balls, mashed potatoes, baked chicken meat with potato slices, baked fish and cooked rice) were subjected to gamma irradiation at doses of 0, 1.5, 3 and 4.5 kGy followed by cold storage (4±1°C). Then the effects of irradiation and cold storage on the microbiological aspects, chemical properties and organoleptic properties of samples were studied. The results showed that irradiation of the prepared meals decreased the counts of total bacteria, total psychrophilic bacteria and total yeasts and molds in all meals, proportionally to the applied dose, and prolonged their refrigerated shelf-life. Moreover, irradiation at dose of 1.5 kGy reduced the counts of enterobacteriaceae, Staphylococcus aureus, Streptococcus faecalis and Bacillus cereus, while 3kGy dose completely eliminated the present enterobacteriaceae, Staphylococcus aureus and Bacillus cereus in all meals, in addition to Streptococcus faecalis in samples of baked chicken with potatoes, baked fish and cooked rice. Salmonella was not detected in all irradiated and non-irradiated meals, while Vibrio spp were absent in irradiated and non­ irradiated baked fish. On the other hand, ganuna irradiation had no effects on the chemical composition of meals/ or their main component, while increased the thiobarbitnric acid (TBA) for cooked meat balls, baked chicken meat and baked fish meat but did not affect their total volatile basic nitrogen (fVBN) nor the contents of trimethylamine (TMA) in fish meat. However, cold storage gradually increased the values of TBA, TVBN and TMA in irradiated and non-irradiated samples. Finally, irradiation treatments had no effects on the sensory properties for appearance, odor and taste of all meals and extended their time of sensory preferance.