Oxidation activity in ready-to-eat oranges

Blood oranges present suitable characteristics for preparation as ready-to-eat products. During shelf-life, such produce could be susceptible to quality degradation due to the action of some enzymes, among which polyphenol oxidase (PPO) and ascorbate oxidase (AAO), considered as two markers of oxidation and reduction of anthocyanins and ascorbic acid. PPO activity was very low, probably due to the low pH of oranges; furthermore, it was noticed that the decrease of phenols and anthocyanins content did not have a statistically significant relation with PPO activity course during storage. Otherwise, AAO activity was very high and correlated to the decrease of vitamin C content. Nevertheless, such decrease did not exceed 20-30% of the initial ascorbic acid content.