Study on preparation process of antioxidant peptide from the lower temperature pressed rapeseed dregs with the synergy of microorganism and enzymes

In this paper,the preparation process of antioxidant peptide from the lower temperature pressed rapeseed dregs with the synergy of microorganism and enzymes was reported. Bacillus subtilis,Saccharomyces cerevisiae,Aspergillus nige and A. oryzae were used for the rapeseed dregs liquid fermentation with alkaline protein enzyme. According to the rapeseed peptide's antioxidant activity tested by potassium ferricyanide reduction method,the following optimal operations were conducted that the single factor experiment of solid-liquid ratio,pH,fermentation temperature and time,strains combination and microorganism-enzyme ratio were separately done firstly. And then,the response surface test used the factors on solid-liquid ratio,pH,fermentation temperature and time was carried out as well. The best parameters combination was B. subtilis,A. nige and A. oryzae strains(V:V:V=1:1:1),microorganism-enzyme ratio was 1:1 (V/V),inoculums size was 10%(V/V),rotational speed was 150 r/min,solid-liquid ratio was 1:20 (g/mL),pH 8,fermentation temperature was 36℃ and fermentation time was 36 h.And the peptide antioxidant activity reached the highest absorbance of 1.26 at this optimization condition. In addition,the oxidative stability of rapeseed peptides prepared used the optimal process was tested and the result showed that at the given maximal concentration of 0.7648 mg/mL,it had a good scavenging activity to superoxide anion and DPPH radical,which the scavenging rate was separately 67.4% and 76.78%. And its inhibition of lipid peroxidation reached 61.5% at the same concentration. The result showed the better antioxidant activity of the prepared rapeseed peptides.