Variation in Protein and Isoflavone Contents of Collected Domestic and Foreign Soybean (Glycine max (L.) Merrill) Germplasms in Korea

Abstract

This study was carried out to investigate the variations in protein and isoflavone contents of 300 soybean germplasms introduced from domestic and foreign countries and to compare their contents in terms of size, colour and country of origin. The protein content ranged from 28.7 g 100 g−1 to 44.5 g 100 g−1, with an average of 39.0 g 100 g−1. In a comparison of protein according to country of origin, the highest content was seen in soybeans from Korea (39.7 g 100 g−1), followed by North Korea (39.2 g 100 g−1), China (39.0 g 100 g−1), Japan (38.8 g 100 g−1), the USA (38.0 g 100 g−1) and Russia (37.2 g 100 g−1). The total isoflavone content ranged from 207.0 µg g−1 to 3561.8 µg g−1, with an average of 888.8 µg g−1. In the comparison of isoflavone content according to country, the highest average content was shown in soybeans from Japan (951.3 µg g−1), followed by the USA (918.7 µg g−1), Korea (902.2 µg g−1), North Korea (870.0 µg g−1) and Russia (710.6 µg g−1). Daidzein, glycitein and genistein isoflavone contents were positively correlated, while total isoflavone and protein showed a low negative correlation.