EXOPOLYSACCHARIDE-PRODUCING LACTIC ACID BACTERIA – HEALTH-PROMOTING PROPERTIES AND APPLICATION IN THE DAIRY INDUSTRY

Abstract

Exopolysaccharides (EPS) are one of the classes of extracellular biopolymers synthesized by bacteria. Some strains of lactic acid bacteria (LAB) used in the dairy industry are able to synthesize EPS (EPS(+) strains). EPS may be secreted by a cell in the form of capsule or slime. Our review describes the factors influencing the activity of EPS production by LAB, the impact of the use of EPS(+) strains on the quality of fermented milk products (yoghurt, cheeses, etc.) and pro-health properties of EPS produced by LAB. The capability to synthesize EPS by LAB depends on many factors, e.g., affiliation to species and characteristics of strain, growth stage, composition of culture medium (type of carbon and nitrogen sources, and presence of other nutrients), temperature, pH, and presence of adjuvant microflora. The presence of EPS synthesized by LAB strains has a significant effect on changes in various properties of dairy products, including: yoghurt, kefir and many other fermented milk drinks, sour cream and cheeses. The EPS act as thickening, emulsifying and gelling agents, hence the use of EPS(+) strains may become a certain alternative to the use of thickeners in, e.g., fermented milks. During formation of a casein milk curd, EPS are able to bind water and thus reduce syneresis. The high water holding capacity of EPS has a positive effect on increasing viscosity and improving texture of low-fat cheeses. EPS are claimed to have health-promoting properties, like: anticarcinogenic, antioxidative, immunomodulatory and reducing blood cholesterol.