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Summary: The aim of this study was to examine the fermentation characteristics of a novel Leuconostoc mesenteroides strain (XR1) and to investigate the effect of XR1 exopolysaccharides (EPS) on the microstructure, texture and rheological properties of yoghurt. The novel Leuconostoc mesenteroides strain (XR1) was isolated from wild kefir grains obtained from Xinjiang Province. The results showed that XR1 had good EPS production capacity and favourable fermentation performance. The addition of XR1 EPS to fermented milk effectively improved the water‐holding capacity (WHC) of the fermented milk and changed its microstructure. In subsequent fermentation studies, the XR1 strain was found to be a compatible strain, and the steric barrier formed between XR1 EPS and the fermented milk proteins enhanced its viscoelastic properties. Rheology studies indicated that fermented milk supplemented with EPS possessed a higher modulus (G', G") and complex viscosity. Thus, these results indicate that XR1 EPS are useful as a natural organic additive that can replace chemical additives in dairy products. [ABSTRACT FROM AUTHOR]

Studies regarding the effects of extracellular polysaccharides produced by high-quality Kefiran production strains on the quality of yoghurt products and the mechanism of action during fermentation and production of yoghurt products are scarce in the literature. However, these studies are highly significant in the development of starters for the yoghurt industry. In this study, a Leuconostoc mesenteroides XR1 strain that produced exopolysaccharides (EPS) was identified and isolated from kefir grains collected from Xinjiang, China. XR1-EPS has similar flocculation characteristics to xanthan gum and higher emulsifying activity than locust gum. A rheological test of the dairy product sample after fermentation of XR1 single bacteria proved that XR1-EPS can impart higher viscosity and elasticity to fermented milk. Results also showed that XR1-EPS can maintain the water-holding ability of the fermented milk and provide a positive thixotropic fluid. In this study, XR1-EPS was isolated in the laboratory for the first time and was shown to be useful as a natural organic additive that can replace chemical additives in dairy products. • Leuconostoc mesenteroides XR1 was isolated from Kefir grains in Xinjiang province. • Strain XR1 showed good exopolysaccharides (EPS) production ability. • XR1-EPS is composed of glucose, with and an enthalpy change value (H) of 676.5 J/g. • XR1-EPS has a smoother surface morphology than xanthan gum. • XR1-EPS fermented milk showed higher viscosity and water-holding ability. [ABSTRACT FROM AUTHOR]