Effect of soaking on isoflavonoid content of soymilk prepared with household machine

Soybean soaking may activate the endogenous enzyme to certain extent and affect the isoflavonoid content of soymilk. In our study,soybean soaked at different temperature was used to prepare soymilk and HPLC was adopted to determine their isoflavonoid profile. It was found that isoflavonoids in soymilk were mainly genistin and daidzin. Content of genistin,daidzin and their aglycones in soymilk prepared from dry soybean were 71. 50,60. 30,6. 80 and 5. 10 mg / L,respectively. When soaked soybean was used as material, content of total isoflavonoid,genistein and daidzein in soymilk were significantly higher than those from dry soybeans. Under the optimal soaking conditions,i. e.,60 ℃ for 1. 8h,the content of genistin,daidzin and their alglycones were 75. 17,62.84,10. 66,and 7. 58 mg / L respectively. Compared to soymilk prepared with dry soybean,the soymilk based on 60 ° C soaked beans showed 56.8% and 48. 6% higher content of genistein and daidzein respectively.Meanwhile,the soymilk made from 60 ℃ soaked beans showed superiority on total solid and protein content to its counterpart. Thus,soaking conditions as 60 ℃ for 1. 8 h could be used to improve biofunction of household machine prepared soymilk.