Abstract:

Three Lactobacillus helveticus strains (JCM1120, CICC6024 and L0906) were individually used to ferment fat-free milk powder. During 30 hours of fermentation, the changes in degree of hydrolysis (DH), pH and number of small peptides were examined periodically. The results indicated that CICC6024 strain had the strongest acid-producing ability and resulted in the highest maximum DH and the contents of small peptides in milk fermented by Lactobacillus helveticu CICC6024 and JCM1120 both reached their maximum amounts at 16 h; however, the fermentation activity of L0906 strain was relatively lower and still did not reach the peak at 28 h. In addition, 19 peaks with height of more than 20 mAU were observed in the RP-HPLC profile of the 16 h fermentation product of stain CICC6024. These investigations suggest that CICC6024 is an optimal strain for the production of small peptides derived from fermented milk and the optimal fermentation period is 16 h.

Key words: Lactobacillus helveticu, pH, degree of hydrolysis, content of small peptides