The Relation between the Lipoxygenase Activity and the Ripeness of the Satsuma mandarin

Abstract

This study aimed at clarifying the causes of the off-flavor which occurred during the process of concentratin Satsuma mandarin orange juice. As linoleic and linolenic acids were previously found in the lipids of Satsuma mandarin orange, its lipoxygenase activity was investigated in correlation to the ripeness of the fruit in the year 1973-4 and 1974-5. The fruits were periodically collected from one settled Satsuma mandarin orange tree in Yamakita, Kanagawa prefecture.
The fruits were divided into two parts: the carpels and the albedo, each of which was extracted with phosphate buffer(pH 7.0), followed by the precipitation of the enzyme with alcohol(final concentration 20%). The lipoxygenase activity was measured by the ultraviolet absorption method.
The moment when the lipoxygenase activity in the carpels reached maximum was in the middle of November or early December, which was4or8weeks earlier than the time when the degree of ripeness reached maximum. The ripness was evaluated from the ratio of sugar content of sugar content to citric acid content.