Living Factories Biotechnology SG Biology

Learning Outcomes 1 State that the raising of dough and the manufacture of beer and wine depend on the activities of yeast. Identify yeast as a single celled fungus, which can use sugar as food Using a word equation, state the process of fermentation of glucose by yeast. Describe the process of anaerobic respiration and compare it with aerobic respiration

Biotechnology Biotechnology is the use of microbes and raw materials to produce useful substances.

Biotechnology Raw materials Suitable micro- organisms Biotechnological process Services Sewage treatment Water purification Products Food, enzymes Fuels Anti-biotics, hormones

Products of Biotechnology

Structure of Yeast Yeast is a single celled fungus It multiplies by budding

Yeast Yeast breaks down glucose into carbon dioxide and ethanol. – In bread making, the carbon dioxide helps the bread to rise. – In brewing, the yeast turns sugars into alcohol. Present on fruits, such as grapes as a bloom (grey dust).

Fermentation in Yeast Fermentation is respiration in the absence of oxygen (anaerobic respiration). It can be represented by an equation. Glucose carbon dioxide + ethanol + energy

Stages in Bread making Add yeast to a warm sugar solution and allow to grow and produce bubbles. Add a pinch of salt to the flour Mix together into a dough Leave mixture in a warm place covered by a cloth Yeast releases CO 2 bubbles making dough rise Bake dough in a hot oven Yum Yum

Baking Yeast is added to, and. is made which is folded and left in a warm place. (anaerobic respiration) causes the yeast to produce ethanol and carbon dioxide. The causes the dough to rise. The dough is then baked in the oven which kills the yeast and removes the. After baking the bread is ready.

Stages in wine making Crush grapes to release juice Filter juice into fermentation tank Add yeast to grape juice Yeast grows using sugar and changes it into alcohol (CO 2 is allowed to escape) Alcohol becomes concentrated and kills the yeast Wine siphoned into bottles

Wine making are crushed and the grape juice is filtered off. is added to the grape juice. takes place, yeast uses the sugar in the grape juice to make and. The is allowed to escape. As the builds up it kills the yeast. The wine is removed into bottles and allowed to.

Learning Outcomes 2 Describe how commercial brewers provide the best growing conditions for yeast. Explain what is meant by the term “batch processing” Explain the need for malting of barley before use by the brewing industry.

Growing conditions for Yeast Food supply – Starch is converted to sugar for yeast by germinating barley grains on the floor of the malting house ( malting) Suitable temperature – Optimum temperature maintained in fermenter vessel by a thermostat Lack of competition – Other microorganisms killed by boiling in the wort kettle

Brewing A brewer is interested in both the alcohol and the carbon dioxide made by the yeast. – Beer is expected to be alcoholic – the carbon dioxide gives the characteristic fizz.

Brewing Raw materials – Barley grains – Water – Extra sugar – Hops – Live yeast By products – Cattle food – Fertiliser – Yeast extract

Brewing (1) Barely grains which are full of, which is a large molecule that yeast can not digest Barley grains are allowed to germinate. – Starch is converted to sugar. This is called. Yeast is added and takes place.

Brewing (2) Yeast changes the maltose into carbon dioxide and ethanol. As the level builds up the yeast is killed. Beer is then made and allowed to. To brew the best beer the brewer must make sure his fermenter vessels are _ and that he uses the temperature for the yeast.

Learning Outcomes 3 State that the manufacture of cheese and yoghurt depends on the activity of bacteria. State that the souring of milk is a fermentation process. Explain the souring of milk in terms of bacterial fermentation of lactose.

Fermentation of Lactose When the bacteria growing in milk respire anaerobically, they use the milk sugar lactose as food. Lactose  lactic acid This is called lactic acid fermentation

pH Days Souring of milk Bacteria feeds on lactose producing lactic acid. Milk becomes more acid and its pH falls.

Cheese and yoghurt production Lactic acid makes milk curdle Special strains of bacteria are used in fermentation in curdling milk.

Flow diagram for the manufacture of yoghurt Bulk raw milkpasteurisation cooler Incubation at 42 o C for 6 – 8 hours Chiller 5 o C Packaging Cool Storage 4 o C

Cheese and yoghurt Cheese – Bacteria added – Milk curdles – Rennin (enzyme) used to separate milk into curds and whey – Whey run off – Curds cut into blocks and mixed with salt to slow bacterial growth – Packed into moulds Yoghurt – Bacteria added to pasteurised milk – Milk clots – Yoghurt formed – Put into tubs and stored in fridge