# Describe how Lactobacillus is used to produce yoghurt from milk.

> Pearson Edexcel International GCSE Biology (4BI1) — 5.1 Food production · Describe · 4 marks

> Yoghurt is a widely consumed dairy product made using microorganisms. The process involves specific conditions to ensure the correct fermentation of milk.

## Mark scheme (4 marks)

1. Lactobacillus is a bacterium (not a fungus or yeast) used to ferment milk
2. Lactobacillus converts / ferments lactose (sugar in milk) into lactic acid
3. The lactic acid lowers the pH / makes the mixture more acidic
4. The lower pH causes the milk proteins to denature / coagulate / solidify, forming the semi-solid texture of yoghurt

## Key terms

- [Lactobacillus](https://www.gradenine.co.uk/glossary/lactobacillus)

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