Lactic Acid Fermentation Improves the Bioaccessibility and Functional Quality of Reduced‐Calorie Sour Cherry Beverages During Cold Storage

ABSTRACT This study aimed to investigate the fermentation of reduced‐calorie sour cherry‐based beverages using three individual probiotic strains ( Lactiplantibacillus plantarum SH5, Limosilactobacillus fermentum SH10, and Lactiplantibacillus pentosus SH14) and one mixed‐strain formulation, and to evaluate these beverages together with unfermented control beverages in terms of their physicochemical, microbiological, bioactive, and cytotoxic properties during 28 days of cold storage. The fermented beverages exhibited pH values of 3.54–3.63, turbidity of 0.614–0.779, total soluble solids of 24.93–29.87 °Brix, and dry matter content of 27.62%–30.75%, with color parameters recorded as L * (15.08–16.66), a * (12.80–18.21), and b * (–5.78 to −3.05). Phenolic profiling identified catechin (31.05–32.90 ppm), chlorogenic acid (10.82–11.05 ppm), and myricetin (5.05–6.90 ppm) as the predominant compounds, although most phenolics gradually declined during storage. Despite higher initial total phenolic content (TPC) in control samples, lacto‐fermented beverages exhibited superior recovery values (%), indicating enhanced bioaccessibility during in vitro digestion. Calorie reductions reached up to 46.46% in SCN9‐SH10, while viable LAB populations remained above 10 6 CFU/mL throughout 21 days of storage (7.01–7.65 log CFU/mL). TPC ranged from 214.75 to 353.67 mg gallic acid equivalent (GAE)/100 mL, DPPH scavenging activity from 213.54 to 274.02 mg Trolox equivalent (TE)/100 mL, and cupric reducing antioxidant capacity (CUPRAC) values from 924.46 to 1576.71 mg TE/100 mL, with fermented samples consistently demonstrating higher antioxidant capacity than controls. Antibacterial activity was observed only in SCN9‐Mix and control samples against Bacillus cereus ATCC 11778, while cytotoxicity assays indicated modest inhibitory effects toward MCF‐7 breast cancer cells, with cell viability ranging from 87.64% to 94.45% in freshly prepared samples and decreasing over 28 days. Collectively, these findings demonstrate that lactic acid fermentation effectively enhances the functional, microbiological, and bioactive properties of reduced‐calorie sour cherry‐based beverages.