EFFECT OF GAMMA RADIATION ON MICROBIAL AND CHEMICAL CHARACTERISTICS OF SOME FOODS

Abstract

Gamma irradiation technology is one of the most effective food preservation methods used alone or in combination with other techniques for microbial decontamination and pathogen elimination. It has positive effects in destroying the pathogenic microorganisms as well as improving the safety and shelf stability of food products without compromising the nutritional or sensory quality. In the present study, the effect of gamma irradiation on microbial load and physicochemical characteristics of minced beef meat and concentrated mango juice has been evaluated. Samples of minced beef meat and concentrated mango juice were irradiated using a Cobalt60 irradiation source at doses (0, 2, 4, 6, 8 and 10 kGy) of gamma irradiation. Irradiated and non-irradiated samples were kept in a refrigerator (4–5 oC) during storage periods. Microbiological and physicochemical analyses were done immediately after irradiation and throughout the storage periods at 7 days intervals. The results indicated that all doses of gamma irradiation reduced the total bacterial count, spore forming bacteria, total fungi, Staph. aureus, Salmonella, Shigella, total coliforms, and fecal coliform in all irradiated samples. Thus, the microbiological shelf-life of all samples of beef meat and mango juice, except a sample with 2 kGy was significantly extended more than 4 weeks in meat and 12 weeks in mango juice. No significant differences in moisture, protein content, fat content, ash values, and total acidity of beef meat were observed due to irradiation. However, pH values decreased significantly with increasing irradiation doses in comparison with control. On the other hand, total soluble solids, total sugars, total phenols, total flavonoids, antioxidant activity and pH values increased due to irradiation in mango juice, but total acidity and ascorbic acid values decreased significantly. While, no significant differences in moisture and ash values were observed with increasing irradiation doses in comparison with contro