Comparative Analysis of Proteolytic Activity and Bioactive Peptide Generation by Lactic Acid Bacteria in Fermented Whey

Lactic acid bacteria (LAB) are pivotal in dairy fermentations, largely due to their proteolytic systems which enhance product digestibility and release bioactive peptides. This study presents a thorough biochemical evaluation of the proteolytic effectiveness of specific LAB strains-Lactococcus lactis, Lactobacillus acidophilus compared to commercial starter cultures. Whey fermentation was monitored over 24 hours, analyzing protein concentration, free amino group release, peptide size distribution, and hydrolysate profiles via SDS-PAGE. L. lactis demonstrated superior proteolytic capacity, yielding the highest protein concentration (4.2 ± 0.5 mg/mL) and the most rapid release of free amino groups (14.3 ± 0.6 mg/mL at 24 h). Size fractionation revealed L. lactis generated 40% peptides <3 kDa, associated with high bioactivity, while commercial cultures retained larger peptides (>10 kDa: 25%). SDS-PAGE confirmed extensive hydrolysis of β-lactoglobulin and α-lactalbumin, particularly after tryptic digestion of L. lactis fermentates. The findings emphasize the strain-specific character of proteolysis and L. lactis as a promising candidate for producing functional whey-based ingredients rich in bioactive peptides.