Optimization on the production of polypeptide from Chinese leek seed meal by Aspergillus niger liquid fermentation

The optimum extraction conditions of bioactive peptides from Chinese leek seed meal by using Aspergillus niger liquid fermentation were investigated using the response surface method ( RSM) and the antioxidant activity of extract was obtained under optimum extraction conditions in order to make full use of the by-product of Chinese leek seed meal. The results indicated that the effect order of the three factors on the peptide extraction from Chinese leek seed meal was fermentation time> substrate concentration > initial p H, and the optimum extraction conditions were substrate concentration 9.4%, initial p H3.0, fermentation time 3 d.Under the optimal conditions, the extraction rate of peptide from Chinese leek seed meal was 573.55 μg/m L.Antioxidant activity of the leek polypeptide from Chinese leek seed meal, including the DPPH· and reducing power measure.The results showed that the leek polypeptide possessed antioxidant properties in vitro.And with the concentration of polypeptides increasing, its antioxidant activity gradually becomes stronger.