Valorization of Whey Permeate Through Kefir Fermentation: Aflatoxin B1 Binding and Cytoprotective Effects

Aflatoxin B1 (AFB1), a potent carcinogenic metabolite produced by Aspergillus flavus and A. parasiticus, constitutes a significant threat to food safety. Conventional decontamination methods are costly or ineffective. Biological detoxification has emerged as a promising alternative. Kefir, a fermented milk beverage, comprises lactic acid bacteria (LAB) and yeasts with documented antifungal properties. This study evaluated whey permeate (WP) as a fermentation substrate for kefir microorganisms and assessed their AFB1-binding capacity. Kefir microorganisms cultivated in WP supported active fermentation, reaching 8.47 log CFU/mL LAB and 7.57 log CFU/mL yeasts, with concomitant lactose consumption and organic acid production. The ability of 13 individual kefir-derived microorganisms and the total kefir microbial community to bind AFB1 was evaluated under diverse conditions. All microorganisms exhibited AFB1 binding ability, although binding depended on strain, growth medium, pH, microbial concentration, and toxin concentration. The highest binding was observed for the total kefir community grown in WP. Binding remained stable over time for the total kefir community and Lactiplantibacillus plantarum CIDCA 83114 and was independent of viability and hydrophobicity. AFB1 binding by kefir microorganisms significantly reduced AFB1-induced cytotoxicity in HepG2 cells. These findings demonstrate that WP can be valorized into a value-added fermented product containing microorganisms with strong AFB1 binding and cytoprotective properties.