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In this post, we'll talk about the food production using yeast and bacteria in I/GCSE Biology. Let's get started! 😆
Food Production Using Yeast
- Yeast is a single celled organism, each of which have a Nucleus, Cytoplasm and a Membrane surrounded by a cell wall.
- Do you remember what mitosis is in I/GCSE Biology?
- The way in which they reproduce is by asexual Mitosis.


- When yeast cells have plenty of Oxygen they respire Aerobically.
- When the yeast cells break sugar down Anaerobically, they produce Ethanol and Carbon Dioxide.
- This process is called Fermentation. The Carbon Dioxide makes dough rise when making bread.


Food Production Using bacteria
Making Yoghurt
- Traditionally, yoghurt is fermented whole milk but now we can make it from semi-skimmed, skimmed and even soya milk.
- Yoghurt is formed by the action of bacteria on the Lactose (Milk Sugar) in the milk.
- A starter culture is added to warm milk, and then the culture reproduce, grow, and ferment.
- As the bacteria break down the Lactose In the milk, they produce Lactic Acid which gives yoghurt its sharp tangy taste.
- This is known as Lactic Fermentation. It also clots the milk to a smooth, thick texture.
In I/GCSE Biology, make sure you can understand the term of lactic fermentation!

Cheese Making
- Like yoghurt making, cheese making depends on the reaction of bacteria with the milk.
- Like yoghurt making, you add a starter culture of bacteria to warm milk. The difference is the type of bacteria.
- The bacteria in cheese making also converts Lactose to Lactic Acid, but makes much more of the acid.
- As a result the solid curds are much more solid.
- Enzymes are also added to increase the separation of the milk.
- When it has curdled you can see the separate Curds and Whey.
- The curds are used for cheese making. Then other bacterium can be added to alter the flavour of the cheese.

And we're done with this topic! Well Done!

Drafted by Alyssa (Biology)
References:
- "Simple diagram of yeast cell (en).svg", https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Simple_diagram_of_yeast_cell_%28en%29.svg/2560px-Simple_diagram_of_yeast_cell_%28en%29.svg.png
- "discuss the process of reproduction in yeast", http://images.topperlearning.com/topper/tinymce/imagemanager/files/biology/cbse_7/198842_Budding_Yeast.png
- "Aerobic and Anaerobic Respiration (Part 1 of 2)", https://i.ytimg.com/vi/GhsxnXGojqc/maxresdefault.jpg
- "Biotechnology", https://v1.nitrocdn.com/kDXDIJNDOaszRbpagqNqUtquAQQkiLpO/assets/static/optimized/rev-ddee88e/wp-content/uploads/2020/01/Yeast-bread.png
- "Lactic Acid Fermentation Process Scheme", https://thumbs.dreamstime.com/z/lactic-acid-fermentation-process-scheme-labeled-vector-illustration-diagram-biological-stages-glucose-pyruvate-lactate-169878458.jpg
- "The Genealogical World of Phylogenetic Networks", http://1.bp.blogspot.com/-Naonn4wwhPA/U90X-a6fn-I/AAAAAAAAC8U/SvHN9GU_BSY/s1600/CheeseMaking.gif