Analysis of Isoflavone Contents of Soybean By-products with Acid Hydrolysis Method

산 가수분해시 가열방법과 시간 및 추출조건에 따른 대두가공 부산물의 이소플라본 함량 변화

  • Han, Jin-Suk (Div. of Food Science, Dong-Eui Institute of Technology) ;
  • Hong, Hee-Do (Traditional Food Research Division, Korea Food Research Institute) ;
  • Kim, Sung-Ran (Food Function Research Division, Korea Food Research Institute)
  • 한진숙 (동의과학대학 식품과학계열) ;
  • 홍희도 (한국식품연구원 전통식품연구본부) ;
  • 김성란 (한국식품연구원 식품기능연구본부)
  • Published : 2006.12.29


To establish a rapid and effective method for the analysis of soy isoflavone which is known to have lots of variation in derivatives of glucoside, conversion rate from isoflavone conjugates to its aglycones, and decomposition of conversed aglycones were investigated with various acid hydrolysis conditions. A number of heating conditions for acid hydrolysis including heating at convection oven $(105^{\circ}C)$, water bath $(95^{\circ}C)$, heating block $(120^{\circ}C)$, and hot plate $(120^{\circ}C)$ were applied. Acid hydrolysis in heating block with reflux was chosen as the best heating condition. From the stability test of isoflavone aglycone during acid hydrolysis, genistein, daidzein, and glycitein did not show any significant changes in their contents for 60 min of hydrolysis. Ten to thirty milligram of sample per 1 mL HCl was the best ratio of sample to acid. As conclusion, acid hydrolysis for 60 min after addition of 15 mL HCl solution to 0.5 g soybean, and then fill up to 50 mL with methanol, followed by HPLC analysis was set as a final analysis method. From this method, isoflavone contents expressed as total aglycone of feed meal was the highest with content of $1288.5{\mu}g/g$ followed by those of dehulled meal.


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