Seasonal Changes in α-and β-Amylase Activities in Relation to Starch Content in Kiwifruit

Abstract

This paper describes the seasonal changes in starch content, and α-and β-amylase activities of two cultivars of kiwifruit, 'Koryoku' and 'Hayward'. The main purpose of the study was to investigate the seasonal changes in starch content in relation to α-and β-amylase activities and also to examine the properties of these two enzymes in both cultivars. The highest activity of α-amylase in the insoluble fraction was observed in September for 'Koryoku'and in October for 'Hayward', whereas that of β-amylase in the same fraction was observed in October for both cultivars. Both enzyme activities were higher in the insoluble than in the soluble fraction. The highest starch content in 'Koryoku'was observed in the middle of October, while in 'Hayward' it was observed in the later part of October or early November. In both cultivars, α-amylase activity peaked one month earlier than starch content.