THIS IS COMMONLY ASKED IN I/GCSE BIOLOGY
- Equipment is sterilised to kill all bacteria
- Then the milk is stirred thoroughly to mix it up
- The milk is then pasteurised, at 72 C for 15 seconds, to killl of the harmful bacteria.
- Then a starter culture of Lactobacillus bacterium is added, then the mixture is incubated at 40 C in a fermenter.
- The lactobacillus ferment the lactose in the milk and then makes lactic acid
- The lactic acid lowers the pH of the milk, this causes the milk to coagulate (solidify) into yoghurt, some samples are taken at this stage to test the consistency of the yoghurt
- The yoghurt is then cooled and flavourings are added, then packaged.
Drafted by Catrina (Biology)