Polyphenol oxidase and peroxidase activity in apple: Dependency on cultivar and fruit processing

Abstract

Apples are an important source of polyphenolic and most popular fruits worldwide. Due to their phenolic content, consuming apple in a diet tend to low risk and prevention some chronic diseases. The main enzyme is responsible for quality loss, which are affecting by phenolic degradation, are polyphenol oxidase (PPO) and peroxidase (POX). PPO and POX are correlated to the rate of browning with substrate content and enzyme activity. The objective of this research was to investigate the polyphenol oxidase (PPO) and peroxidase (POX) activity in different apple cultivars. Apples Gravin Goldach, Bay 4152, Sonnen Glanz, Gala Mitslugla apples were obtained from an orchad of Hohere Bundeslehranstalt und das Bundesamt fur Wein und Obstbau in Klosterneuburg, Vienna, Austria, then Apple from each cultivar was cut and separated in two parts, peel with seed (red flesh) and peel without seed (white flesh), then PPO and POX were determined. The results showed that tThe highest PPO activity is presented by red flesh of Bay 4152 cultivar, whereas the lowest detected in red flesh Gala Mitslugla. PPO activity on apple flesh of red Bay 4152, white Sonnen Glanz, red gravin Goldach and red Gala Mitslugla were 5.01E+04, 4.79+04, 3.17+04 and 1.91E+04 ΔE/S/Kg protein, respectively. PPO activity on apple flesh was not affected by white or red colour. The highest POX activity was found in red flesh of Sonnen Glanz cultivar, whereas the lowest value was presented in white flesh of Gravin Goldach cultivar varied from 1.07E+05 to 7.68E+04 ΔE/S/Kg protein. In all different flesh of apple cultivars showed that the high or low POX activity was not resulted by the red or white flesh coloured. POX is much higher than PPO activity of all cultivars. Result will provide to maintain the phenolic related quality loss and to improve new processing method.