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Yogurt fermentation

Yogurt is made by fermenting milk with friendly bacteria, mainly Lactobacillus bulgaricus and Streptococcus thermophilus. Yogurt fermentation was invented probably by accident by Balkan tribes thousands of years ago. Yogurt remained mainly a food of eastern Europe until the 1900s, when the biologist Mechnikov created the theory that lactobacillus bacteria in yogurt are responsible for the unusually long lifespans of the Bulgar people. The milk sugar or lactose is fermented by these bacteria to lactic acid which causes the characteristic curd to form. The acid also restricts the growth of food poisoning bacteria. During the yogurt fermentation some flavours are produced, which give yogurt its characteristic flavour. Yoghurt can easily be made at home using a live yogurt as the starter culture. To make you own yogurt use the following process. Bring the milk (or soymilk) to boiling point and cool down to 40- 45°C. Pour this milk in a sterile container and and per liter milk about 100 ml live yogurt. Mix with a sterile spoon and incubate at 40-44°C during 4 to 6 hours or until the yogurt is set. Put the yogurt in the refrigerator. If you worked under hygienic conditions, you can use your own yogurt as a starter for your next batch.

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