Microbial Exopolysaccharides: A Review of Their Function and Application in Food Sciences

Extracellular polymeric substances are defined as high molecular weight compounds secreted by the microorganisms in the surrounding area. Since these extracellular substances are mainly polysaccharide, they are named exopolysaccharide. Microbial exopolysaccharides composed of sugar residue have growing interest as a new class of microbial products which can be used in food, pharmaceutical, and biomedical industries. Microbial derived exopolysaccharides are considered as either good substitute of other synthetic or natural polymers or novel biopolymers which are used in food for thickening, suspending and gelling function. However, microbial derived compounds have a versatile reputation and the numbers of published articles in this area are increasing, only three exopolysaccharides xanthan, gellan and dextran have been survived the industrial competition. Considering the extensive function of microbial exopoly-saccharides and the importance of physical properties and chemical structure in functionality determination, the function and application of microbial exopolysaccharides are discussed with the emphasis on physical properties and chemical structure in this review.