Starter cultures play an important role in the production process of dairy products. Whether it is kefir, yoghurt, quark or soured milk - the right use of microorganisms contributes significantly to the success of a production.
Kefir is a viscous sour milk product in which yeasts play an important role in addition to fermentation by lactic acid bacteria. Yeast fermentation predominates at lower temperatures and carbonic acid and alcohol are formed. The lower lactic acid content results in a milder product.
Yoghurt is a product with a long tradition. Today, as then, yoghurt is produced by acidifying and coagulating specifically selected lactic acid bacteria. Depending on the composition of the mixtures and the processing form of the milk product, a choice can be made between firm or stirred yoghurt and a mild or sour product.
Mesophilic starter cultures which are active at low temperatures of 20-22 °C are used for producing quark. Curdling only becomes visible after 6 to 8 hours.
After the addition of lactic acid bacteria to pasteurised or homogenised milk, the milk is thickened after some time due to the flocculation of the casein and the curdled milk becomes sour milk. The added lactic acid cultures are mesophilic (preferred temperature between 22 and 28 °C) and lead to coagulation of the milk over a period over a period of 15-20 hours.
The sweet whey from the cheese dairy is pasteurised and cooled to 22-28 °C. This is the optimal temperature for mesophilic bacteria. Acidification with pH values between 4.40 and 4.30 occurs over a period of about 16 to 18 hours after adding the cultures.