Abstract:

The ultrafiltration method for preliminary separation and purification of antioxidant peptides from kidney bean protein hydrolysates (KBPHs) prepared by Alcalase-catalyzed hydrolysis was introduced. The effects of main parameters on membrane flux and different cleaning agents on recovery of membrane flux were investigated. The molecular weight distribution, the amino acid composition and the antioxidant activity of KBPHs before and after ultrafiltration were analyzed and compared. Modified PES plate-form ultrafiltration membrane exhibited purifying effect on antioxidant bioactive peptides from KBPHs in contrast with other three membranes. The optimal conditions of ultrafiltration were: KBPHs concentration 2.5%, pH 6.5, pressure 0.25 MPa, and temperature 25 ℃. Fractions of high relative molecular mass were effectively removed from KBPHs and the contents of fractions of relative molecular mass ranging from 2000 to 1000 and below 1000 were increased from 11.38% to 32.83%, and from 12.64% to 45.91%, respectively after ultrafiltration. Additionally, the antioxidant activity of KBPHs was increased as well.

Key words: kidney bean protein, enzymatic hydrolysis product, ultrafiltration, antioxidant activity