Preservation of meat cutlet employing gamma radiation under different packaging systems

Abstract

Ready-to-fry beef cutlets were prepared in the Department of Livestock Products Technology, College of Veterinary and Animal Science, Mannuthy. They were packaged under aerobic condition in HDPE packets and under vacuum in PA-PE packets. Half number of samples was subjected to irradiation employing gamma irradiation at 2.5 kGy. Samples were stored under room temperature (25-30oC) and in chiller (3-4oC). Samples were analysed for proximate composition on the day of preparation and for pH, TBARS, TV, microbiological and organoleptic qualities on day 0, 5, 10, 15, 20, 30, 45, 60 and 70 of chiller storage. Shelf life of beef cutlet was assessed on the basis of physical signs of spoilage. The nonirradiated samples kept at room temperature were spoiled within 21 h, whereas irradiated sample had the keeping quality of 34-42 h (IRAP and IRVP). In chiller condition the NRAP sample spoiled within 12-15 days, whereas irradiated sample had a shelf life of 50-55 days. The shelf life was 19-22 and 66-71 days in NRVP and IRVP samples, respectively. The proximate composition, Ca and P content were not affected due to irradiation. The pH of the sample was not affected due to irradiation in different treatments, storage and packaging. TBARS and tyrosine value were unaffected by packaging and irradiation, whereas on storage the values were increased. Aerobic plate count, psychrotrophic plate count, yeast and mould count were significantly reduced due to irradiation, while packaging had not shown any significant effect. About 76 per cent reduction in aerobic plate count, 74 per cent reduction in psychrotrophic count and 70 per cent reduction in yeast and mould count was noticed. As storage period enhanced the counts were increased. Since the products are stored under chiller condition the survived bacteria might have been multiplied and count has gone up. The organoleptic qualities were assessed with help of 9 point Hedonic scale. The colour and flavour of the product were unaltered due to irradiation or packaging on the day of preparation. The juiciness and tenderness score had increased due to irradiation with the highest values of tenderness in IRVP samples. The overall acceptability was not affected due to irradiation or packaging on the day of preparation. A gradual decrease in overall acceptability and other score were observed due to storage with IRVP sample scoring the highest. The irradiation preservation of beef cutlet was beneficial for enhancing the keeping quality of beef cutlet under chiller conditions without affecting the qualities. Microbial count like aerobic plate count, psychrotrophic count, yeast and mould count were significantly (P<0.05) reduced due to irradiation at 2.5 kGy, the lowest limit prescribed by PFA. Vacuum packaging of the product combined with irradiation has shown about 25 per cent increase in keeping quality compare to ordinary packaging and 4 times increase compared to nonirradiated samples. Irradiation of the product combined with chiller storage requires less electrical energy for preservation of the product. Considering the extended shelf life, wholesomeness of the product, reduced microbial load and energy saving aspects vacuum packaging followed by irradiation can be advocated as a suitable method for preservation of meat and meat products.