EFFECTS OF LOW Co 60 GAMMA RADIATION ON MICROBIAL FLORA AND SHELF LIFE OF PEANUTS

Abstract

The present study aimed at reducing the microbial content thereby enhancing the shelf life of peanuts through Co60 gamma irradiation dose optimization. Peanut pods were obtained from local fruit market of Lahore and were shelled under hygienic conditions that were later subjected to irradiation at 0.3, 0.75, 0.9kGy of doses. Effect of radiation treatment on microbial quality and insect infestation of samples kept at room temperature was analysed after every 30 days of interval for up to 60 days. Total bacterial count obtained for all samples ranged from 105 to 106 whereas no log reduction was observed in treated samples as compared to control. No gram negative Enterobactereace were observed either in control or treated samples. All doses were able to reduce fungal growth to 104 that remained persistent throughout the experimental period. Fungal species identified were Aspergillus niger, Aspergillus flavus, Fusarrium spp., Penicillum spp. and Rhizophus spp. Conclusively, low Cobalt-60 gamma irradiation treatment could prove effective if combined with physical or chemical treatments before packaging.