A Most starter culture manufacturers offer body-building cultures for use in products such as sour cream, yogurt and buttermilk. In fact, most yogurt and buttermilk starters contain at least one strain of body-builder. What exactly do these muscle-bound cultures do, and how do they do it?

Some, but not all strains of a variety of species of lactic acid bacteria, including Lactococcus lactis ssp. lactis and cremoris, Streptococcus thermophilus and Lactobacillus bulgaricus, are able to produce extracellular polysaccharide (EPS). In the starter culture industry these strains are often referred to as body building because the strains impart certain attributes to the finished product that are not simply due to the production of lactic acid. The EPS that these cultures produce during fermentation is composed primarily of high-molecular weight carbohydrate (polysaccharide) and is often referred to as "slime." EPS produced by the starter may remain closely associated with the cell (capsular polysaccharide), may be loosely associated with the cell or may be secreted into the medium. For sake of simplicity, all types of extracellular polysaccharide are often referred to simply as EPS.