STARCH BREAKDOWN AND CHANGES IN AMYLASE ACTIVITY DURING RIPENING OF ETHYLENE- AND ETHANOL-TREATED BANANAS

Authors:	J.U. Agravante, T. Matsui, H. Kitagawa
Abstract: Starch breakdown in ethylene- and ethanol-treated bananas was examined at different stages of ripening at 25°C and related to its - and -amylase activities. The pulp contained about 10% starch at the green stage (PCI 1) and less than 1% at the ripe stage (PCI 5). Total sugars increased from 1% at PCI 1 to 20% at the fully ripe stage (PCI 6) and declined in overripe and deteriorated fruits. Sucrose constituted more than 60% of the total sugars at PCI 5. Reducing sugars increased until senescence (10%). Starch and sugar composition of the fruits were not affected by the treatments. -amylase did not change markedly during ripening but tended to be higher in yellow than in green fruits. -amylase activity increased as starch was degraded and declined when hydrolysis was virtually complete. The increase was highest in ethylene- and lowest in ethanol-treated fruits. However, starch breakdown was not strictly dependent on the activity of - and -amylase.
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