Characterization of Bioactive Peptides Produced by Hydrolysis of Whey Proteins by Lactic Acid Bacteria

The valorization of whey, a ubiquitous byproduct of the cheese industry, is a significant focus for sustainable food production. This study investigates the enzymatic hydrolysis of whey proteins by lactic acid bacteria (LAB) as a bioprocess for generating bioactive peptides. Lactococcus lactis, Lactobacillus acidophilus, and a commercial mesophilic starter culture were employed to ferment a whey protein isolate (WPI) solution. The resultant hydrolysates were fractionated via gel filtration chromatography, revealing a starkly superior capacity of L. lactis to generate low-molecular-weight peptides (<3 kDa), which constituted approximately 40% of its total peptide content, compared to ~30% for L. acidophilus and 20-25% for the commercial culture. Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) analysis indicated that the L. lactis-derived peptide fraction possessed a markedly hydrophobic character, a trait strongly correlated with enhanced bioactivity. Subsequent identification using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) confirmed the presence of specific, well-documented bioactive sequences, including the potent ACE-inhibitory peptide VLPVPQK and the antimicrobial peptide IPAVFK from L. lactis, the immunomodulatory peptide YPFPGPIPN from L. acidophilus, and the antioxidant peptide LLYQEPVLGPVR common to both strains. These findings underscore the critical importance of strain selection in targeted bioprocessing and position L. lactis as a highly promising microbial catalyst for the industrial production of whey-derived bioactive peptide fractions for nutraceutical and functional food applications.