Evaluation of microbial potential and ripening behavoiur of preclimacteric bananas following gamma irradiation

Abstract

The current study was carried out to evaluate the effects of gamma irradiation on the epiphytic microflora and ripening process of the green Dwarf Cavendish bananas harvested at the three-quarter stage of the maturity. The mature green bananas were irradiated using Cobalt-60 as the source of irradiation at different dosages of 0.5, 0.75 and 1.0 kGy. The mean life of both the experimental and control group of fruits was analyzed under ambient conditions. For all the treatments the microbial potential, the decay percent and the ripening behavior of the fruits were recorded. Results revealed that the applied radiation doses reduced the decay incidence, delayed ripening process and greatly inhibit the microbial growth (total bacterial and fungal count) thereby enhancing the shelf life of bananas. Irradiation dose of 1.0 kGy was found to be the most effective dose to positively maintain the stored bananas under ambient conditions. The mean life of bananas was extended by 14 days. The identification of the enteric bacteriaeaceae through API 20 E strips revealed the presence of Shigella sonnie on the fruit surface along with Escherichia coli and a nonfermentor spp. The dominant spoilage causing fungi identified were Aspergillus niger, Aspergillus flavus, Collotrichum musae, Fusarium oxysporum, Mucor spp, Lasiodiplodia theobromea and Rhizopus stolonifer.