Characteristics of the exopolysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus AWT1-12 and its effect on the quality of nonfat set yogurt

Based on the structural characterization and functional analysis, this study aimed to systematically elucidate the intrinsic relationship between molecular characteristics and functional properties of an exopolysaccharide (AWT1-12-EPS1) produced by Lactobacillus delbrueckii subsp. bulgaricus AWT1-12, and further explore its potential application as a natural additive in nonfat set yogurt. The molecular weight of AWT1-12-EPS1 is 42.8 kDa, is primarily composed of glucose and mannose, has a rough, porous surface, and exhibits excellent thermal stability (311°C), gelling properties, and antioxidant activity. Three concentrations (0.1, 0.5, and 1 g/L) of AWT1-12-EPS1 were incorporated in the nonfat set yogurt. All concentrations of AWT1-12-EPS1 enhanced the compactness of the microgel structure in fermented milk and improved the hardness, viscosity, water-holding capacity, antioxidant activity, flavor, and storage stability of the yogurt. Correlation analysis demonstrated that its functional properties were closely associated with molecular weight, monosaccharide composition, and surface porous structure. This study elucidates the conformational relationship of this exopolysaccharide and provides a theoretical basis for its functionalization in dairy products. • A novel exopolysaccharide produced by lactic acid bacteria was discovered. (AWT1-12-EPS1). • The structure and core functions of extracellular polysaccharides (AWT1-12-EPS1) were analyzed. • Extracellular polysaccharide enhances nonfat yogurt's texture, flavor, and antioxidant activity.