Biochemical changes involved in stress response and ripening behaviour of γ-irradiated mango fruit

The stress response of ripening mango fruits treated in the pre-climacteric phase with radiation doses of 0.75, 1.25 and 1.75 kGy was investigated. L-Phenylalanine ammonialyase, polyphenol oxidase, peroxidase and catalase activities were determined and significant differences were observed. Differences in the patterns of total phenolics, flavanols and proteins were also observed. Malic enzyme activity was used as an indicator of the ripening stage (climacteric rise, climacteric peak and post-climacteric phase) as well as a measure of the effect of γ-irradiation on fruit ripening. It seems that radiation treatment causes a stress condition in the fruit which, depending on the dose, may lead to browning of the tissue or necrotic decay.