Comparison of isoflavones and anthocyanins in soybean [Glycine max (L.) Merrill] seeds of different planting dates.

The concentrations of isoflavones and anthocyanins in five soybean seed cultivars of three different planting dates were determined in this study. Among the seeds of three different planting dates, the highest concentration of average total isoflavones (4098 μg g(-1)) was measured in those from early July, whereas the lowest concentration of average total isoflavones (3238 μg g(-1)) was measured in those from late May. Anthocyanin compounds were detected only in the Cheongjakong 3 cultivar. Among the three different planting dates, late-planted Cheongjakong 3 accumulated the highest concentration of total anthocyanins (10103 μg g(-1)), whereas the variety at an earlier planting date exhibited the lowest concentration of average total anthocyanins (7115 μg g(-1)). On the basis of these results, it was concluded that environmental factors such as temperature and precipitation may change the isoflavone and anthocyanin contents of soybean, altering the nutritional values of soy products.