S9: Making Yoghurt

Question 1

What is yoghurt?

Answer 1

Fermented milk

Question 2

What sugar does milk contain?

Answer 2

Lactose

Question 3

What bacteria produces lactic acid?

Answer 3

Lactobacillus

Question 4

Why does milk coagulate?

Answer 4

The lactic acid decreases the pH of the milk, increasing its acidity and making it sour, which causes the proteins in the milk to clump together and causes the milk to solidify and form yoghurt

Question 5

Name the stages of making yoghurt

Answer 5

Sterilization

Homogenization

Pasteurization

Adding Lactobacillus

Fermentation

Coagulation

Question 6

When making yogurt why does sterilization take place?

Answer 6

To remove any unwanted bacteria on the equipment, so that there are no pathogens that can contaminate the production of yoghurt

Question 7

When making yogurt why does Homogenization take place?

Answer 7

To break down the fat droplets in the milk and disperse it thoroughly through the liquid

Question 8

When making yogurt why does Pasteurization take place?

Answer 8

The milk is heated to 80-95*C to kill any pathogens

Question 9

When making yogurt why does Lactobacillus get added?

Answer 9

So that the bacteria can convert the lactose in the milk to lactic acid.

Question 10

When making yogurt why does fermentation take place?

Answer 10

It’s done in a large scale industrial fermenter to allow the optimum conditions for the bacteria to create the product

Question 11

When making yogurt why does coagulation take place?

Answer 11

The lactic acid decreases the pH of the milk, increasing its acidity and making it sour, which causes the proteins in the milk to clump together and causes the milk to solidify and form yoghurt