Abstract
The cysteine protease, actinidin, in kiwifruit is known to inhibit gelatin gelation by hydrolyzing gelatin. The gelatinolytic activity in the fruit juice was examined in 13 kiwifruit cultivars obtained in Japan. Whereas the gelatin was thoroughly hydrolyzed by the kiwifruit juice in most of the cultivars, the Hort16A and Kosui fruit juice showed little or no gelatinolytic activity. The protease activity against L-pyroglutamyl-L-phenylalanyl-L-leucine p-nitroanilide in Kosui fruit juice was about 6% of that in Hayward, the most common kiwifruit cultivar. The addition of sliced or pureed flesh of Kosui to the gelatin jelly did not prevent the jelly from setting. The protease activity in Kosui puree, when added to gelatin jelly at 50%, caused only a 4-10% decrease in the gel strength. These results suggest that the raw fresh of Kosui kiwifruit can be satisfactorily used as an ingredient in gelatin-based foods.
