Fermented Milks | Starter Cultures

Abstract

The major functions of fermented milk starter cultures are to extend shelf life and enhance safety due to the biopreservative function of metabolites produced, and also to enhance the sensory, rheological, as well as nutritional properties of fermented milks. For optimum function of the starter cultures, safety, purity, and stability of active starter cultures need to be maintained. In addition, optimum fermentation condition and milk as growth medium are also important factors in producing fermented milk. All fermented milk starter cultures produce acids. Lactic acid bacteria are the most important groups, primarily used because of their ability to ferment lactose, resulting in the production of lactic acid for homofermentative starter cultures, but some starter cultures, namely heterofermentative starter cultures, may also perform other metabolic activities, such as carbon dioxide production in kefir, exopolysaccharide formation contributing to thicker consistency of fermented milk, and production of flavor compounds such as diacetyl. Problems encountered in fermented milk industry, mostly due to the presence of bacteriophage and antimicrobial substances that may inhibit the activity of bacterial starter cultures, resulted in decreased viscosity and reduced flavor development.