BIOLOGY REVISION

YOGHURT

1. The equipment is streilised, this kills off microorganisms.

2. Milk is pasteurised, and then cooled.

3. A starter culture of bacteria is added, mixture is incubated in a fermenter.

4. Bacteria ferments lactose sugar in mlk to form lactic acid. Lactic acid causes the milk to solidify into yoghurt.

5. Flavours and colours can be added to the yoghurt which is then packaged.

SOY SAUCE

1. Cooked soy beans and roasted wheat are mixed together.

2. Mixture is fermented by Aspergillus fungus.

3. Mixture is fermented again by yeasts,

4. Mixture is fermented again by Lactobacillus bacterium.

5. The liquid is then filtered.

6. It's then pasteurised and put into sterile bottles.