Partial Purification, Characterization, and Application of Exopolysaccharides Produced by Lactobacillus plantarum NS1905E in Yogurt

Exopolysaccharides (EPS) of lactic acid bacteria (LAB) has gained special interests in the dairy industry due to their health-promoting properties and contribution to the rheology of fermentation milk products. In the present study, an EPS designated as EPS-NS1905E was partially purified and characterized secreted from L. plantarum NS1905E. The EPS-NS1905E had an average molecular weight of 2.658 × 105 Da and was composed of glucose, arabinose, rhamnose, mannose, and galactose in an approximate molar ratio of 58.83 : 17.4 : 6.31 : 5.86 : 2.74. The FTIR spectroscopy showed the prevalence of carboxyl and hydroxyl groups. The EPS-NS1905E had a thermal stability and exhibited higher viscosity in the NaCl solution and low acidity conditions (pH 2–4). Furthermore, the EPS-NS1905E possessed strong scavenging abilities against DPPH radicals (96%). The addition of EPS-NS1905E in skim milk significantly shortened the fermentation time of yogurt, and the water-holding capacity (WHC) and viscosity of yogurt were improved during storage. The results indicated that the EPS-NS1905E has great potential for use as a food additive in the food industry.