This study is aimed at investigating the feasibility of casein glycomacropeptide (GMP) hydrolysates as potential prebiotics in yogurt. The growth performance of Bifidobacterium animalis subsp. lactis (Bb12) was determined in the presence of GMP hydrolysates produced by the action of proteolytic enzymes (trypsin and papain) with various degrees of hydrolysis. The growth-promoting effect of GHP on Lactobacillus bulgaricus and Streptococcu thermophilus were also evaluated. Results showed that the optimum hydrolysis time of GMP with trypsin or papain for Bb12 growth promotion was 2 and 0.5 h, respectively. Compared with GMP and its trypsin hydrolysate, the GMP hydrolysate produced with papain (GHP) was the best for Bb12 growth, which obtained the highest viable count (9.3 log cfu mL−1) and the lowest pH of 4.69. The obtained GHP significantly improved the growth of S. thermophilus (P < 0.05), while it had little effect on the growth of L. bulgaricus (P > 0.05)., The viable count of Bb12 of the yogurt obtained with the addition of 1.5% GHP was about four times higher than that of the control without GHP addition. The growth-promoting effect of GHP might be related to its high content of Glu, Leu and Ala while had no direct relationship with sialic acid content.Summary
Glycomacropeptide (GMP) hydrolysates supplemented in yogurt could improve the growth of Bifidobacterium animalis subsp. lactis (Bb12) and S. thermophilus, while has little effect on L. bulgaricus.