Optimization of in situ exopolysaccharides production by Lactobacillus helveticus MB2-1 in yogurt and its vitro functional characteristics

Abstract In order to improve the in situ exopolysaccharides (EPS) production of Lactobacillus helveticus MB2-1 in Sayram ketteki yogurt and explore its functional characteristics, the production optimization, rheology and microstructure of fermented yogurt, and emulsifying properties, antioxidant, antibiofilm activities of the in situ EPS were investigated. Based on the results of response surface methodology (RSM), the fermentation temperature 37℃, fermentation time 8.0 h and incubation amount 7.0% (w/w) was the optimum condition for L. helveticus MB2-1 growth and yogurt formation, and the obtained production of in situ EPS could be up to 340 mg/L. Under the optimized fermentation conditions, the rheology analysis illustrated that the Sayram ketteki yogurt fermented by L. helveticus MB2-1 formed better gel structure than the control yogurt. Besides, the in situ EPS presented fine emulsifying properties, which could be comparable to other biological emulsifiers. The in situ EPS exhibited potent antioxidant activities as well. Moreover, the antibiofilm activities of the in situ EPS on foodborne pathogens biofilm formation were obvious. Taken together, the results illustrated that the EPS produced in situ by L. helveticus MB2-1 in Sayram ketteki yogurt has the potentiality to be considered as a beneficial substitute for functional food products.