The role of irradiation on microbiological safety and shelf-life extension of non-sterile and sterile convenience meat products stored at ambient temperatures

The effect of gamma irradiation in combination with vacuum packaging on the microbiological and sensory quality of Intermediate Moisture (IM) buffalo, chicken or lamb meat cubes, and number of ready-to-cook ethnic meat products stored at ambient temperature (30 ± 2 deg. C) was studied. Irradiation treatment (2.5, 5 and 10 kGy) resulted in a dose-dependent reduction in the total viable count as well as levels of potentially pathogenic Staphylococcus spp. and these samples remained microbiologically superior to their non-irradiated counterparts upon extended storage. Irradiation (10 kGy) treatment of vacuum packed IM spiced lamb and chicken cubes resulted in a product in which no viable microorganisms could be detected for 12 months of storage at ambient temperature (30 ± 2 deg. C). Initial analysis of non-irradiated samples showed total viable counts of >106 CFU/g, Staphylococcus counts of >105 CFU/g and mould counts of 103 CFU/g which upon 3 months of storage under similar conditions spoiled showing visible mould growth. Ready-to-use shelf-stable mutton and chicken sheek kababs, mutton and chicken chilli were developed by reducing the water activity either by grilling or by hot air-drying, vacuum packing and irradiation. Microbiological analysis revealed a dose-dependent reduction in the total viable count and in potentially pathogenic Staphylococcus spp. upon irradiation treatment (2.5, 5 and 10 kGy). The products subjected to irradiation at 10 kGy showed an absence of viable microorganisms and also had high sensory acceptability up to 9 months at ambient temperature. Amenability of various ready-to-cook and ready-to-eat chicken, mutton and pork products for radappertization using locally available packaging material was evaluated. The sensory quality of all products without gravy was found to be acceptable. However, traditional gravy based products showed changes in the sensory attributes (colour and flavour) leading to lower acceptability of the products. (author)