The influence of biosynthesized exopolysaccharides on some characteristics of fermented dairy products

In the current technology of fermented milk products, the ability to form exopolysaccharides (EPS) is a basic criterion to be used for the selection of starter cultures, together with their capacity to produce lactic acid, aroma substances, stability and texture. This paper aimed at screening lactic acid bacteria to be used as starter cultures for yogurt production based on their ability to biosynthesized exopolysaccharides. In case of the YF-L812 starter culture, the ability to synthesize EPS depended on the dry matter (DM) of the milk: a quantity of 93 mg EPS/l was recorded for the whole milk reconstituted to 14.5% DM and 80 mg EPS/l for the sample reconstituted to 11.5% DM. The investigation at the microstructure level revealed that yogurt obtained from reconstituted milk to 14.5% DM had a dense network gel with a high syneresis phenomenon, whereas yogurt made from reconstituted milk to 11.5% DM formed a network gel with large alveolar cavity enough to hold the entire amount of whey.