Synergistic antifungal and anti-aflatoxigenic effects of lactic acid bacteria and golden berry in a functional high-protein beverage

High-protein beverages are valued for their health benefits, but they face threats from toxigenic fungi and mycotoxins This study developed a novel, functional high-protein beverage (HPB) by synergistically combining whey protein concentrate (WPC), fermented by specific bacteria, with Physalis peruviana (golden berry) powder (at a 1:5; w/w). Three bacterial strains—Lactobacillus plantarum (BS-2), L. pentosus (BS-1), and L. paracasei (BS-3)—were involved for the fermentation, individually and in combinations. Fortification with golden berry significantly enhanced the phytochemical profile, increasing phenolic content (22.97 ± 0.56 mg GAE/g), flavonoids (97.15 ± 2.58 mg QE/g), and antioxidant capacity compared to the control. The BS-2 strain exhibited the strongest antifungal activity, inhibiting fungal growth by 53.8 ± 0.41% and completely suppressing the aflatoxin B2 production by Aspergillus parasiticus. Rheological analysis showed that BS-2 and the three-strain mixture significantly increased viscosity (p < 0.05), enhancing beverage stability. Sensory evaluation (n = 40) revealed that the BS-2 fermented Physalis-HPB was the most preferred, earning the highest overall score. During 21-day shelf-life tests under fungal challenge, beverages fermented with BS-2 and mixed strains maintained the lowest fungal CFU counts at 4 °C, demonstrating superior microbial stability. These findings show that combining P. peruviana with probiotic fermentation enhances the functional, sensory, and safety qualities of HPBs, suggesting a promising bio-based approach to reduce fungal spoilage and mycotoxin hazards in dairy beverages.