Preparation of ACE inhibitory peptide from walnut glutelin-1 by enzymatic hydrolysis
In order to obtain high-quality raw materials for the preparation of angiotensin converting enzyme(ACE)inhibitory peptide from walnut protein and optimize its preparation process,five component proteins including albumin,globulin,prolamin,glutelin-1 and glutelin-2 were separated from defatted walnut meal using continuous extraction method in turn.The proportion and ACE inhibition rates of the five component proteins were determined.The component protein with the largest ACE inhibition rate was used as raw material to prepare ACE inhibitory peptide by enzymatic hydrolysis.On the basis of selecting the optimal enzyme,the enzymatic conditions for the preparation of walnut protein ACE inhibitory peptide were optimized by single factor experiment combined with response surface methodology.The results showed that the proportion of glutelin-1 in the five component proteins was second only to glutelin-2,and its ACE inhibition rate was the highest.With walnut glutelin-1 as raw material and pepsin as enzyme,the optimal enzymatic hydrolysis preparation conditions of walnut glutelin-1 ACE inhibitory peptide were obtained as follows:enzymolysis temperature 46 ℃,enzymolysis time 6 h,enzyme dosage 4.2%(based on the mass of substrate),and enzymolysis pH 1.6.The ACE inhibition rate of the enzymatic hydrolysate obtained under the optimal conditions was(50.08±2.34)%.Enzymatic hydrolysis of walnut glutelin-1 by pepsin can produce walnut polypeptides with higher ACE inhibitory activity.