چکیده (انگلیسی):

The preservation of food by fermentation is one of the oldest methods known to mankind. Fermented dairy products are popular due to their differences in taste and their favorable physiological effects. A typical example is lactic acid fermentation, which is widely used for the preparation of several fermented milk products, such as dahi (curd), yoghurt, sour cream, kefir, acidophilus milk and various varieties of cheeses. Starter cultures have a multifunctional role in dairy fermentations. Dairy starter cultures are carefully selected microorganisms, which are deliberately added to milk to initiate and carry out desired fermentation under controlled conditions in the production of fermented milk products. Most of them belong to lactic acid bacteria (Lactococcus, Lactobacillus, Streptococcus and Leuconostocs). In some cases, few non-lactic starters (bacteria, yeast and mold) are also used along with lactic acid bacteria during manufacturing of specific fermented milk products. Today, fermented dairy products in general are produced locally by using traditional methods. Recently, due to the increased demand for natural nutrients and probiotic products, fermented dairy products have reached a different position and are considered to have an important impact on human health and nutrition.