Phosphorylase, Phosphatase, α-Amylase Activity and Starch Breakdown during Ripening of ‘Marmelo’ Banana [(Musa acuminata Colla) × (Musa balbisiana Colla) ABB Group] Whole Fruit and Thin Slices1

Abstract

Starch hydrolysis, phosphorylase, phosphatase and α-amylase activity of ‘Marinelo’ banana (Musa acuminata Colla × Musa balbisiana Colla, ABB group) during ripening of whole fruit and thin slices infiltrated with water (controls), cycloheximide and actinomycin D were investigated. Phosphatase and α-amylase activity of whole fruit increased during the climacteric while phosphorylase decreased as starch degradation proceded. Starch degradation had a different temperature coefficient than that of α-amylase activity when the storage temperature was raised from 20 to 25°C and stopped when 25% of the starch was still present. Activity of α-amylase in slices infiltrated with water, increased before the onset of the climacteric as a result of injury and at the same time starch was being hydrolyzed. Cycloheximide inhibited this induced activity increase but not starch breakdown or the increase of activity which occurs during the climacteric. Actinomycin D did not inhibit the α-amylase increase and its effect was a general retardation of ripening.