The sweetness of fruits depends on SSC, because most of soluble solids of fruits are sugars. In this study, we first analyzed the ratio of sugar content to SSC in ripening fruits of four different cultivars(two Japanese cultivars, one American cultivar and one Chinese Cul-tivar). The data showed that on an average 86% soluble solids were sugars regardless of the value of SSC (Table 1). Because it is very simple and fast to measure SSC and the ratio of sugar content to SSC is constant, we only analyzed SSC in the next experiments.