Biochemical Studies on Changes in Quality of Post-harvest Fruits during Storage

Part IV. Changes in gluconeogenesis and amylolysis during after-ripening in chilling-injured banana fruit

Abstract

Changes in starch and sugar contents and in enzyme activities related to gluconeogenesis and amylolysis during the process of after-ripening in chilling-injured banana fruits were compared with those of healthy fruit.
In the healthy fruits, a linear increase in sugar contents and a sharp decline of starch contents started on the 6th day of storage at 20°C, accompanying with increase in phosphofructokinase (PFK) activity. While apparent fructose-1, 6-diphosphatase (F1, 6 DPase) activity stayed relatively low and constant level.
In contrast, a gradual increase in sugar contents accompanying with a remarkable increase in apparent F1, 6DPase activity but no significant change in starch contents were noted in the fruits stored at 6°C.
Storage at 20°C after the storage at 6°C for 9 days caused a rapid increase in sugar contents and sharp decline of stach contents within 5 days. In these chilling-injured fruits, however, a low PFK activity and a remarkably high apparent F1, 6DPase activity were noted throughout after-ripening.
These findings suggested that, in chilling-injured fruits, an increase in gluconeogenesis occurred preceding to after-ripening and an increase in amylolysis also occurred during the process of after-ripening.