Starch Breakdown in Ethylene- and Ethanol-treated Bananas: Changes in Phosphorylase and Invertase Activities during Ripening

Abstract

This paper describes the changes in phosphorylase and invertase activities during ripening of bananas subjected to ethanol and ethylene treatments.
Starch content in the banana pulp decreased from about 20% at the green stage to less than 1% at the fully ripe stage while total sugar increased to 20%. At the same stage of ripeness, the starch and sugar contents, and enzyme ativities of ethanol- and ethylenetreated fruits were comparable to that of the control.
Phosphorylase activity increased during the period of rapid starch breakdown(peel color index 2) and declined at the later stages of ripening, concurrent to the decrease in starch content. On the other hand, invertase activity was very low at the green stage but increased sharply at peel color index 3 (more green than yellow)concomitant to the increase in sucrose.