1 / 26

Biotechnology

Biotechnology. Living Factories. G Davidson. Yeast at Work. Yeast is a tiny living thing. It is called a microbe. It is used in baking and brewing. Yeast at Work. Yeast makes many useful products. E.g. yeast can break down glucose into carbon dioxide and ethanol (alcohol).

rex
Download Presentation

Biotechnology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biotechnology Living Factories G Davidson

  2. Yeast at Work • Yeast is a tiny living thing. • It is called a microbe. • It is used in baking and brewing. G Davidson

  3. Yeast at Work • Yeast makes many useful products. • E.g. yeast can break down glucose into carbon dioxide and ethanol (alcohol). • This is called fermentation. • Yeast obtains energy by doing this. G Davidson

  4. Yeast Cells G Davidson

  5. Simple Fermenters • A fermenter is a vessel which can be used to manufacture a range of products in the presence or absence of oxygen. • Yeast can be used to ferment sugars to produce many useful substances for man. G Davidson

  6. Simple Fermenter G Davidson

  7. Large Fermenters G Davidson

  8. Brewing • Wild yeasts are to be found on most fruits, seeds and flowers. • Long ago people found that when they stored fruits, seeds and flowers in water, new liquids were made. • These were called wine and beer. G Davidson

  9. Brewing • The wild yeasts were responsible for this. • Today, only particular strains of yeast are used in brewing and wine-making. • To make beer which can be sold to the public, commercial brewers must give the yeast the best growing conditions. G Davidson

  10. Taking Care of Yeast • Living yeast is used in fermentation. • It usually works best at temperatures between 10oC – 18oC and a pH of about 7. G Davidson

  11. Taking Care of Yeast • Given these conditions, a controlled supply of oxygen and sugar as food, yeast will grow well. • It is also important that unwanted microbes are kept out. G Davidson

  12. Starch & Germination • Starch is present in barley grains. • This starch cannot be used by yeast as a food. • First of all brewers must germinate the barley. • Barley grains contain enzymes. • Germination allows the enzymes in the barley to act on the starch. G Davidson

  13. How Yoghurt is Made G Davidson

  14. How Yoghurt is Made • Milk can be changed into cheese and yoghurt. • This preserves milk. • People have done this for hundreds of years. G Davidson

  15. How Yoghurt is Made • Certain bacteria are used in this process. • Two strains of bacteria are used to make yoghurt. • They ferment the milk sugar (lactose) into lactic acid. • This acid makes the milk curdle and go lumpy and gives yoghurt its sour taste. G Davidson

  16. Cheese Making G Davidson

  17. How Cheese is Made • Bacteria are added to the milk to make it go sour. • Next an enzyme called rennin is added. • This breaks down the proteins in milk and forms the solid curd. G Davidson

  18. How Cheese is Made • The liquid whey is then drained off. • The curd is finally allowed to ripen and mature to form cheese. • Some cheeses are then flavoured by adding different microbes. G Davidson

  19. Cheese Making G Davidson

  20. Souring of Milk • Bacteria and sugar are present in fresh milk. • The bacteria can feed on the sugar and cause milk to sour. • The souring of milk is a fermentation process. G Davidson

  21. Malting • Nowadays the brewing of beer, which involves malting and batch processing, is carefully controlled using modern scientific methods. • Malting changes the starch in barley into sugars which can be fermented by yeast. • The whole process takes 7-8 days and is carried out in the maltings building. G Davidson

  22. Malting • First the barley is soaked; this is called steeping. • Extra water is then removed and the grain is turned regularly to allow aeration. G Davidson

  23. Malting • At this stage the temperature is carefully controlled to regulate germination of the grain. • When germination begins, enzymes in the grain break down the starch into maltose. • During the brewing process the maltose is converted into fermentable sugars. G Davidson

  24. Maltings Building G Davidson

  25. Batch Processing • This is the technique used by commercial brewers to provide the best conditions for fermentation. • The common feature of all batch processes is that they involve closed systems. • After the addition of the raw materials, nutrients and yeast culture, the system is left untouched, although controlled, until fermentation ends. G Davidson

  26. Batch Processing • The beer is then removed. • Fermentation ends because nutrients run out or waste materials build up. • The growth rate of the yeast is therefore higher at the start, falling to zero at the end. • Batch processing which is monitored and controlled to give optimum conditions maximises the quality and quantity of the beer. G Davidson

More Related