Abstract: The study on the technical conditions of separating protein and isoflavone in soybean whey by ultrafiltration showed that before ultrafiltration, soybean whey should be pretreated to reduce membrane contamination. The orthogonal experiment of 2 factors and 3 levels indicated that the optimum pretreatment conditions were 5% of CaCl₂ addition based on the solid substance content in soybean whey, and heating up at 85 ℃ for 15 minutes. Under these conditions, the precipitation rate of whey protein was 49.8%, while the reservation rate of isoflavone was 90.4%. Single factor experiment showed that the optimum ultrafiltration conditions were poly (ether sulfone) membrane of 10 kDa molecular weight cut-off (MWCO), 51～68 kPa, and 30 ℃～40 ℃. Under these conditions, the retention rate of whey protein and isoflavone was 83.9% and 7.6%, respectively.

Key words: Pyricularia grisea, Infection process, Ecological factor