What is fermented milk

Fermented Milk

It is a product made from raw cow's (goat's) milk or milk powder, sterilized, and fermented to a lower pH value. Fermented milk refers to cow's milk and other animal milk by lactic acid bacteria fermentation process and made of a large class of dairy products, mainly sour cow's milk, active milk, as well as cheese, sour cream and so on. Fermented milk contains a large number of beneficial active bacteria is one of the ideal food for modern human beings with both nutritional and health care functions.

Fermented milk has a long history, early production is the domesticated animal (cows, sheep, goats, buffalo and camel) milk boiled and cooled to 40 degrees through natural fermentation. China does not have a strict definition of fermented milk, but from the foreign language data can still be expressed in the following explanation of fermented milk: through the non-Bulgarian Lactobacillus fermentation (and can occur enzymatically) of all kinds of dairy products.

Fermented milk is a comprehensive name for a class of dairy products of many kinds, including yogurt, kefir, fermented buttermilk, sour cream, milk wine (mainly horse milk), etc. Oberman and Libudzisz (1998) classified traditional fermented dairy products into four categories based on the types of microorganisms predominantly present in fermented milks.

(1) Type I fermented milk

This type of fermented milk belongs to the typical Scandinavian and Central and Eastern European fermented food products, and the dominant microflora are thermophilic Streptococcus lactis and Streptococcus minutus, which usually grows in a temperature range of 10 a 40°C, with an optimal growth temperature of about 30°C. The important characteristics of dairy products made by thermophilic microbial fermentation are its viscosity and aromatic flavor (formed by fermentation of citric acid and lactose).

The strains included in type I fermented milks are Lactococcus lactis subsp. lactis (Lactococcus lactisssp.?1actis), Lactococcus lactis subsp. cremoris (Lactococcus lactisssp.?cremoris), Lactococcus lactisssp.? 1actis var. ?diacetylactis), Lactococcus lactis subsp. intestinalis and Leuconostoc mesenteroidessp. intestinalis. The first two species mainly produce lactic acid, known as organic acid producers; while the latter is mainly fermented citric acid to form some important metabolites such as acetaldehyde, CO2 and butanedione, etc., known as flavor material producers.