Isolation of Bacillus Soil Exopolysaccharides in Desert Areas and Their Effect on the Quality of Molded Yogurt During Cold Storage

One of the most important applications of biotechnology in the food industry is the production of various additives. Among the additives produced by biotechnology method is the production of exopolysaccharides produced by bacteria in dairy products.Diversity in the structure and chemical composition of microbial exopolysaccharides has made them superior to animal and plant polymers. Due to these cases, these compounds can be used as food additives with health effects. In the present study, Bacillus bacteria producing exopolysaccharides were isolated from the soils of desert areas and then, the structural and functional groups of exopolysaccharides were identified using FT-IR method. The presence of peaks in the frequency range 400-4000 (cm-1)indicates the polysaccharide and purity of the extracted material. Then, their effects on the quality of yogurt were investigated. Based on the results, the quality of yogurt samples containing exopolysaccharide of bacteria K, C, B, A and E significantly increased compared to the control group that did not contain exopolysaccharide.Exopolysaccharide from E bacterium significantly reduced hydration compared to other samples and control samples and also significantly increased the viscosity and water holding capacity and consistency of yogurt. Finally, based on the 16S rDNA sequence, the bacterium whose exopolysaccharide had the greatest effect on improving the quality of yogurt, Bacillus wiedmannii strain HBUM207173 was identified.