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In GCSE biology, we learn that microbes make many useful products.
Advantages of using microbes
- Rapid growth
- Minimal space required (because of contained growth)
- Predictable products produced (under controlled conditions)
- May be used together with a bi-product of another process to produce useful products (may grow on waste materials from other processes)
Application
The production of yogurt
- Pasteurised, sterilised milk is used to avoid any unwanted microbes.
- When sterilised, the milk is heated to 72 degree celsius as it kills most of the pathogenic bacteria, without compromising the taste.
- However, this is not hot enough to kill food spoilage in the milk, and the food can still go off.
- The milk is then mixed with specially cultured bacteria and kept to the right temperature 30 degree celsius for the enzymes to work.
- The enzymes in the bacteria ferment the sugar from the milk lactose into lactic acid, which gives the sour taste and makes the product semi- solid.
The production of bread
- The production of bread involves mixing yeast, sugar and flour (made from wheat) and leaving them somewhere warm.
- The bread is then kneaded to introduce oxygen for aerobic respiration.
- The yeast then respires with this oxygen, producing carbon dioxide (fermentation).
- The carbon dioxide gas bubbles through the dough and causes it to rise.
There are many factors which affect the rate of fermentation in yeast, including the amount of yeast, the temperature, and the availability of glucose.
- The enzymes work best in a certain temperature, therefore the temp will affect the rate of fermentation
- The more yeast there is, the quicker the process of fermentation
- The more glucose available, the quicker the yeast can respire, and therefore the quicker the process of fermentation
- The availability of oxygen also affects it in the same way
Biological washing powders
Biological washing powders contain enzymes found in the digestive system:
- Lipases ---> for breaking down fats
- Proteases ---> for breaking down proteins
- Carbohydrases ---> for breaking down carbohydrates.
These enzymes make it easier to remove food from clothes as they break it down.
That's the end of today's topic!
Drafted by Yoshi (Biology)