Microbial Polysaccharides as Food Ingredients

The use of microbial products as food ingredients gained significant attention due to an increased consumer awareness and demand for healthy food products. Microbial polysaccharides produced by bacteria and fungi became prominent in this regard. They show great versatility in their chemical structures and functions, and are thus used as thickeners, stabilizers, gelling agents, encapsulation components, and film-forming agents in the food industry. Microbial polysaccharides, such as curdlan and levan show noteworthy prebiotic and biological activity whereas others, such as gellan, dextran, and cellulose stand out because of their exceptional physical properties. Microbial polysaccharides are superior to plant polysaccharides as they can be produced more effectively, with higher reproducibility, and without being affected by seasonal changes. Xanthan and dextran are already widely used in the food industry; however, some others, such as levan require cheaper production techniques to be feasible as food ingredients. Although chitosan and alginate are usually commercially produced by nonmicrobial techniques, they can also be obtained by microbial fermentation. Chemical modification of microbial polysaccharides can also lead to unprecedented applications. This chapter deals with the chemical structure, general properties, production strategies, food applications, and future trends of the most widely used microbial polysaccharides, namely, curdlan, gellan, levan, pullulan, and xanthan. It also covers cost-effective production techniques for these valuable biopolymers.