Debittering of walnut peptide and the effect of ACE inhibitory activity

Protein was extracted from walnut residue and it was hydrolyzed by neutral protease.The determination of bitterness value was carried out to compare with the debittering effect for walnut peptides by using active carbon and β-cyclodextrin, and meanwhile to investigate their influences on the antihypertensive activity of walnut peptide, to choose a better way to debitterize.The result showed that the order of the influencing factors on debitterize:the amount of active carbon>processing time>pH.When the amount of active carbon was 50%, processing time was 100min, pH value was 8, the bitterness value of the peptide was lowest, while the nitrogen loss rate was larger.When the amount of active carbon got 40%, processing time was 80min, pH value was 7, its minimum nitrogen loss rate was obtained, bitterness value of 2, and the loss of antihypertensive activity was 15.81%.The optimum condition to debitterize using β-cyclodextrin:the amount was 22%, processing time was 30min.Under these conditions, the bitterness value could reduce to 2, the antihypertensive activity could hardly be affected.It was concluded that using β-cyclodextrin to debitterize was better than active carbon treatment.