Yoghurt Production

Question 1

which bacteria is yoghurt made with?

Answer 1

Lactobacillus bulgaricus

Question 2

why is milk pasteurised (heated) when making yoghurt?

Answer 2

to kill bacteria

Question 3

method of making yoghurt

Answer 3

1. the equipment is sterilised
2. the milk is pasteurised by heating
3. the bacterial culture is added to the cooled milk and left at 46 degrees C for about 4 hours which ensures the bacteria’s enzymes are not denatured
4. samples are taken to see if the yoghurt is ready
5. flavours and colours are added, then the yoghurt is packaged
6. yoghurt is cooled to 5 degrees C to help preserve the yoghurt

Question 4

when respiring anaerobically, what does Lactobacillus produce?

Answer 4

lactic acid

Question 5

why does lactic acid act as a preservative?

Answer 5

because it lowers the pH and

Question 6

how does lactic acid give yoghurt its flavour and texture?

Answer 6

the acid coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour