Influence of Cultivation Temperature on Oligosaccharides and Isoflavones in Soybean Sprouts

抄録

The effect of temperature on changes in raffinose family oligosaccharides (RFOs) and isoflavones contents during cultivation period of soybean sprouts was investigated to enrich the basic knowledge on the production method of soybean sprout with high functionality. In this experiment, soybean sprouts were cultivated at 10°C, 15°C, 20°C, 25°C, or 30°C, concurrently respiration rate was measured by the flow-through method using gas chromatography. RFOs such as raffinose and stachyose, and isoflavones were then determined using high performance liquid chromatography. The amount of RFOs was found significantly dependent on cultivation temperature and decreased rapidly at higher temperature. The degradation of RFOs increased remarkably at germination preparation phase and then decreased gradually during radicle elongation phase under all temperature conditions. The purpose of RFOs degradation in growing soybean sprouts during each phase was different. Additionally, the highest amount of remained RFOs was observed in soybean sprouts cultivated at 20°C. In the case of isoflavones, there was no significant difference of total isoflavone glycosides observed among cultivation temperatures. Our results suggest that optimization of the cultivation temperature and the hypocotyl length of the sprouts at harvesting time influence the amount of beneficial RFOs and isoflavones in soybean sprouts.