Comparison of bioactive peptides prepared from sheep cheese whey using a food-grade bacterial and a fungal protease preparation

Novel bacterial (HT) and fungal (FPII) food-grade protease preparations were evaluated for their ability to hydrolyse sheep cheese whey (SCW) and the generation of bioactive peptides. Both protease preparations hydrolysed the whey proteins to small peptides over 24-h hydrolysis time, but the time course hydrolysis profiles were different as evaluated by SDS-PAGE. The HT whey hydrolysate had considerably higher antioxidant and angiotensin-I converting enzyme (ACE)-inhibitor activity than the FPII hydrolysate. Neither hydrolysate was cytotoxic towards Vero cells. OFFGEL electrophoresis of the small peptide pool fraction (<15 amino acids) of each hydrolysate indicated differences in the pI distribution of the bioactive peptides. This likely reflects the diverse hydrolytic specificity of the proteases. Although the antioxidant activity of both hydrolysates was not significantly affected by simulated gastrointestinal digestion, the loss of ACE-inhibitor activity was greater with the FPII hydrolysate.