Unlocking the biological potential of whey proteins through lactic acid bacteria fermentation

Fermenting whey with lactic acid bacteria (LAB) provides a sustainable route to valorize dairy byproducts while generating peptide-rich beverages with health benefits. In this study, a model whey beverage (WM) was fermented for 72 h with twelve LAB strains isolated from raw-milk dairy products. Fermentation resulted in strain-dependent protein hydrolysis and accumulation of low-molecular-weight peptides. Notably, β-lactoglobulin (β-Lg), the major whey allergen, was partially degraded during fermentation, with reductions ranging from 12% to 33%, depending on the strain. Among the tested strains, Lactobacillus delbrueckii subsp. delbrueckii LbL2, despite only moderate overall proteolysis, released the highest levels of peptides <3 kDa (1.05 ± 0.23 mg/mL), typically linked to health-promoting functions. L. delbrueckii subsp. lactis LbL37 showed the strongest antioxidant capacity, increasing DPPH radical-scavenging activity by approximately 40% compared to the unfermented control, while Streptococcus macedonicus LbL43 exhibited the highest ferric-reducing power. The most pronounced ACE-inhibitory effect was observed for St. macedonicus LbL43 (4.07 ± 0.02 mg/mL) and L. delbrueckii subsp. delbrueckii LbL37 (4.07 ± 0.02 mg/mL ) . Several fermentates also inhibited pathogenic bacteria, notably Listeria monocytogenes . These improvements were not linked to extensive proteolysis but rather to a moderate, selective hydrolysis pattern that may have preserved key bioactive sequences. Altogether, this study demonstrates the potential of autochthonous LAB as a promising strategy to produce whey-based fermented beverages with reduced allergenicity, enhanced health benefits, and environmental sustainability by valorizing dairy by-products. • Twelve non-starter LAB strains fermented whey protein concentrate for 72 hours • Strains hydrolyzed whey proteins and released low molecular weight peptides • Lactobacillus delbrueckii subsp. delbrueckii LbL2 generated the highest concentration of peptides <3 kDa • Fermentates displayed enhanced antioxidant, ACE-inhibitory, and antimicrobial activities • Some strains inhibited pathogens like Listeria monocytogenes and Staphylococcus aureus