Purification of Equol from Degradation Products of Soybean Isoflavones Resulting from Lactobacillus delbrueckii subsp. Bulgaricus Fermentation

MRS medium fortified with soybean isoflavones was fermented by Lactobacillus delbrueckii subsp.Bulgaricus at 37 ℃.As a result,soybean isoflavones were degraded,producing equol.Polyamide resin was used for purifying the crude equol extract from the harvested fermentation broth after 48 h fermentation.The optimal adsorption/desorption conditions were determined by single factor and orthogonal array design methods to be: sample concentration 2.40 μg/mL at pH 5,adsorption duration 6 h and amount of 80% ethanol used for equol desorption at a flow rate of 0.5 mL/min 45 mL.Under such conditions,the adsorption ratio of equol was 45.36%,and the desorption raio 60.00%.