How is yogurt made?

Yogurt is produced through the fermentation of milk by lactic acid bacteria, Lactobacillus bulgarius and Streptococcus thermophilus.

The milk is firstly heat treated, homogenised and then cooled to allow the addition of bacteria or starter culture.

Given the right conditions, i.e. correct temperature and moisture, the bacteria are able to ferment the milk sugar (lactose), producing lactic acid.

The milk proteins then coagulate and set, to form yogurt.

A colourless liquid called acetaldehyde is also produced during fermentation and gives yogurt its distinct flavour.

Yogurt can be plain, or it can be sweetened, or flavoured with fruit