Preparation of Antimicrobial Peptides Powder Derived from Bovine Casein Hydrolysates

In order to prepare highly active antibacterial peptides power,casein was extracted from fresh milk and then hydrolyzed with one of four different proteases(neutral protease,alcalase,trypsin and papain).Casein hydrolysates prepared with papain exhited stronger inhibitory effects on Escherichia coli,Salmonella and Staphylococcus aureus than those prepared with neutral protease,alcalase or trypsin.Using one-factor-at-a-time and orthogonal array design methods,the optimal hydrolysis conditions for the preparation of highly active antibacterial casein hydrolysates with papain were determined as following: 50 ℃ of hydrolysis temperature,4.5 h of hydrolysis time,4500 U/g of enzyme amount,pH 5.5,and 6 g/100 mL of substrate concentration.Moreover,we found that both the prepared casein hydrolysates and their lyophilized powder had stable antimicrobial activity.Meanwhile,the lyophilized powder showed slightly stronger antimicrobial activity.