Changes of Protease Activities during the Development and the Storage of Kiwifruits

Abstract

The changes in protease activities were studied during the development and the storage of kiwifruits, (Actinidia deliciosa (A. Chev) C.F. Liang et A.R. Ferguson Cv. Hayward, Abott, and Bruno) harvested from 3 to 25 weeks after anthesis. The stability of protease in acetone powder was also examined. The amounts of free sugars, free amino acids, alcohol insoluble substances and pectic substances were measured, and the correlation between these values and the protease activities were examined.
1. The protease activity increased according to progress of the development. The activity showed high correlation with the yield of acetone powder.
2. The protease activities of kiwi fruits tend to decrease slightly during the storage at 5°C for 20-55 days or at 20°C for 20 days respectively.
3. Protease activities of acetone powder were stable for up to 90 days during the storage at 1°C for 30-150 days.
4. Soluble protein contents increased during the development of the fruit, and a high correlation was shown between the amount of the protein and the protease activity.