Exopolysaccharides isolated from fermented milk-associated lactic acid bacteria and applied to produce functional value-added probiotic yogurt

The current study aimed to isolate and characterize the lactic acid bacteria (LAB)-derived exopolysaccharide (EPS) and apply it to enhance yogurt's functional and technological quality. After screening and isolation of 52 different LAB strains from fermented milk products, Lactobacillus (L.) rhamnosus KF5, L. plantarum C182, Pediococcus (P.) acidilactici CCFM18, and Leuconostoc (Leu.) mesenteroides F27, with high EPS production yield, were nominated for further evaluation. EPS-derived strains were evaluated based on production yield, protein content, antioxidant activity, emulsification, and anti-inflammatory ability. After comparing isolated EPS samples, the Leu. mesenteroides F27 products were chosen in 3 concentrations (100, 250, and 500 mg EPS/L) to supplement the yogurt. EPS at all concentrations enhanced LAB growth, water-holding capacity, viscosity, and antioxidant activity. The electronic nose and tongue revealed that EPS did not affect the yogurt flavor profile. The confocal laser scanning microscopy showed a homogenously distributed protein and EPS network in the supplemented yogurt samples. However, in the rheology and consumer analysis, the 250 mg/L concentration showed better attributes, such as higher consistency, lower flow behavior, and a higher flavor score. Leu. mesenteroides F27-derived EPS could be used as a biological additive to enhance yogurt's technological and functional quality.