This study was carried out to investigate the variation of isoflavone contents among 172 Korean soybean varieties released from 1913 to 2013. The isoflavone contents were also compared by utilization types, seed size and seed color. Cluster analysis was performed to classify the varieties based on the variation of isoflavone contents. The results obtained from the present study are summarized as follows:

1. Total isoflavone contents ranged from 206.3 μg/g to 2666.2 μg/g with an average of 837.2 μg/g. By each component, malonylgenistin content ranged from 99.2 μg/g to 1149.1 μg/g with the highest average of 390.0 μg/g, and glycitein content ranged from 0.1 μg/g to 2.4 μg/g with the lowest average of 0.8 μg/g.

2. Among composition group, the aglycone group contents ranged from 2.2 μg/g to 33.1 μg/g with the lowest average of 10.0 μg/g, and glucoside group contents ranged from 36.9 μg/g to 801.8 μg/g with an average of 202.4 μg/g. The malonylglucoside group contents ranged from 143.6 μg/g to 1796.4 μg/g with the highest average of 599.1 μg/g and acetylglucoside group contents ranged from 3.7 μg/g to 103.9 μg/g with an average of 27.5 μg/g.


3. Varieties with high total isoflavone content were Aga8(2666μg/g), Aga4(2569μg/g), and Aga9(2345μg/g) in bean sprouts group. Varieties with low total isoflavone content were Deawang(328.8μg/g) in soy sauce and paste group, Hanol(599.3μg/g) in vegetable and early maturity group and Gemjeong1(664.1g/g) in cooking with rice group.

4. In comparison among the total isoflavone contents according to utilization types, the highest isoflavone content was observed in the varieties in bean sprouts group(1028.1μg/g) followed by soy sauce and paste group(830.4μg/g) and cooking with rice group(750.1μg/g). The varieties for vegetable and early maturity group(389.0μg/g) showed the lowest isoflavone contents.

5. In comparison among the total isoflavone contents according to seed size, the highest isoflavone contents was observed in the varieties of small seeds(1208.1μg/g) followed by midium(943.5μg/g) and large(691.6μg/g) seeds.

6. In comparison among the total isoflavone contents according to seed color, the highest isoflavone contents was observed in the varieties of yellow seeds(884.7μg/g) followed by black (740.4μg/g) and green seeds(696.6μg/g) and brown seeds(630.0μg/g).

7. The first three principal component axises accounted for 89.14% of the total variation observed. Dendrogram constructed using average linkage cluster method revealed that 172 Korean soybean varieties were divided into seven clusters with the average distance of 0.8 between clusters. The cluster Ⅰ includes 57.6% of the total varieties, which was the largest cluster among seven clusters, the cluster Ⅱ includes 35.5% of the total varieties, which was the second large cluster and the other clusters were small clusters containing less than five varieties.

8. In comparison among the total isoflavone contents according to clusters, the highest isoflavone content was observed in cluster Ⅵ with an average of 2526.9 μg/g, followed by cluster Ⅳ(1546.6 μg/g) and cluster Ⅴ(1503.5 μg/g). The others were found to contain low isoflavone content.