CHANGES IN ISOFLAVONE GLUCOSIDE AND AGLYCONE CONTENTS OF CHICKPEA YOGHURT DURING FERMENTATION BY LACTOBACILLUS BULGARICUS AND STREPTOCOCCUS THERMOPHILUS

摘要

Lactobacillus bulgaricus and Streptococcus thermophilus fermented chickpeanyoghurt with a ratio of 1:1 (v/v) for 6–7 h at 42C. All cultures reached 109 cfu/mLnof chickpea yoghurt. After 8 h, pH and titratable acidity ranged from 5.74 to 4.25nand 0.16 to 0.62%, respectively. Daidzein and genistein increased to 39.92 mg/gnDW (dried weight of freeze-dried chickpea yoghurt) and 50.34 mg/g DW, respectively,nafter a 4-h fermentation. The amount of aglycone genistein and daidzeinnwere more than that of glucoside daidzin and genistin. Total content of the aglyconendaidzein and genistein was 90.26 mg/g DW at 4 h, which was 5.7 times of theninitial fermentation (15.71 mg/g DW). Chickpea yoghurt fermentation hydrolyzednthe isoflavone glucosides, and L. bulgaricus and S. thermophilus converted isoflavonenglucosides to aglycones. L. bulgaricus and S. Thermophilus seemed to beneffective starters for chickpea milk with more aglycones and appropriate acidity.