Combined effect of heat treatment, UV-C and superatmospheric oxygen packing on phenolics and browning related enzymes of fresh-cut pomegranate arils

Abstract

Fresh-cut arils were subjected to hot water dipping at 55 °C for 30 s, UV-C light (4.54 kJ m−2) and passive modified atmosphere packaged or high oxygen (initial 90 kPa O2) active modified atmosphere packaging treatments. Arils were stored at 5 °C and 90% relative humidity up to 14 days. Superoxide dismutase, catalase, peroxidase and polyphenol oxidase activities as well as individual and total phenolics compounds and anthocyanins were assessed. All treatments reduced superoxide dismutase activity. However, UV-C and high oxygen, alone or combined, resulted in arils with the highest superoxide dismutase activity. UV-C + high oxygen treated arils also showed the lowest reduction in catalase activity. Hot water was effective suppressing polyphenol oxidase activity while peroxidase activity increased. All treatments involving high oxygen and/or UV-C kept high anthocyanins and especially phenolic content. Results showed that the decrease of superoxide dismutase and catalase and the increase in peroxidase and polyphenol oxidase might induce quality loss and browning development. The combination of UV-C and high oxygen preserved superoxide dismutase and catalase, had lower values of peroxidase and polyphenol oxidase and maintained the concentration of antioxidant compounds. These treatments seem to be a good option to improve and extend the shelf life of fresh-cut arils.