Varietal differences in actinidin concentration and protease activity in the fruit juice of Actinidia arguta and Actinidia rufa

Abstract

Actinidin, a cysteine protease in kiwifruit, affects the taste, allergenic properties, and characteristics for processing the fruit. The actinidin concentration and the protease activity in the fruit juice of six Actinidia arguta and two A. rufa cultivars were determined by quantitative sodium dodecyl sulfate -polyacrylamide gel electrophoresis and spectrophotometric assay, using L-pyroglutamyl-L-phenyl-alanyl-L-leucine p-nitroanilide as a substrate. In 'Shinzan', 'Hirano', 'Gassan', and 'Mitsuko', both actinidin concentration and protease activity in the juice were much higher than those of 'Hayward', the most common kiwifruit cultivar, whereas protease activities in 'Kosui', 'Awaji', and 'Nagano' were significantly lower. These results indicate that there are varietal differences in actinidin content in the fruit of Actinidia species.