Sugar and Organic Acid Composition in the Fruit Juice of Different Actinidia Varieties

Soluble sugars, sugar alcohol, and organic acid contents in Actinidia fruits at the eating-ripe stage were determined in various genotypes using high-performance liquid chromatography: five A. deliciosa, seven A. chinensis, two A. rufa, eight A. arguta, and three interspecific hybrids. The main soluble sugars in A. deliciosa and A. rufa fruits were glucose and fructose, although sucrose was present in smaller amounts. In contrast, sucrose was the predominant sugar in A. arguta fruits, followed by fructose and glucose. Most Actinidia fruits tested here contained myo-inositol as a sugar alcohol component. In particular, myo-inositol contents in A. arguta fruits were 0.575–0.982 g/100 g fresh weight, which is the highest level among all foods. Regarding the organic acid component, citric and quinic acids predominated over malic acid in all Actinidia fruits tested. Compared to A. deliciosa and A. chinensis, the proportion of quinic acid was higher in A. rufa and lower in A. arguta.