Effect of Lactobacillus plantarum Exopolysaccharide Combined with Fish Gelatin on the Quality Characteristics of Low-Fat Yogurt

The effect of addition of mixtures of exopolysaccharide (EPS) from Lactobacillus plantarum JLAU103 with fish gelatin (FG) in different proportions to low-fat yogurt on its quality characteristics was investigated. The results showed that adding 0.1% (m/m) EPS and 0.6% (m/m) FG improved the water retention and pH of low-fat yogurt, reduced the titration acidity, and resulted in viscosity similar to whole-fat yogurt. Addition of EPS and FG made the network structure of low-fat yogurt more compact, reducing the voids in it. The viable bacterial count of low-fat yogurt was significantly increased to 8.40 × 108 CFU/mL after addition of 0.6% FG and 0.1% EPS (P < 0.05). The contents of characteristic volatile flavor substances such as diacetyl, 2-nononone and 2,3-glutaredione increased significantly, the sensory score increased, and the texture was significantly improved. The rheological results showed that addition of EPS reduced the thixotropic loop area of low-fat yogurt, enhanced the stability and total strain, and caused low-fat yogurt to form a more solid gel network. Therefore, L. plantarum JLAU103 EPS combined with FG can significantly improve the quality of low-fat yogurt, and has a good application prospect.