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Biotechnologia sera


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Biotechnologia sera

  2. 2. What is Biotechnology? Biotechnological process is one that uses microorganisms in various branches of industry, agriculture and medicine.
  3. 3. Outline of cheesemaking proces The basic source for cheesemaking is milk obtained from cows, goats, sheep etc. There are the main stages cheesemaking: 1.Pasteurisation 2. Coagulation -separating the milk into solid curds 3.Maturing of cheese Microorganisms are used in each step of this process and determine the flavor and texture of the final cheese
  4. 4. The 1st step of cheesemaking – pasteurisation The milk is contaminated with bacteria such as E. coli, Salmonella, Listeria that are dangerous for human Pasteurisation is the process of heating up milk and cooling it back down in an effort to minimize the bacterial risk of that product. The key to pasteurisation is to heat the milk to 72 degrees for no more than 15 seconds and then quickly cooling it to 4°C. .
  5. 5. The second and the main step of cheese making– Coagulation Cheesemaking involves separating the milk into solid curds and liquid whey by coagulating the casein protein in milk. Acidifying (souring) milk helps to separate the curds. For this purpose the lactic acid bacteria is added. Curds and whey
  6. 6. Bacteria acidify milk Acidifying (souring) milk helps to separate the curds and whey and control the growth of undesirable bacteria in cheese. Usually special ‘starter’ bacteria are added to milk to start the cheesemaking process. These bacteria convert the lactose (milk sugar) to lactic acid and lower the milk’s pH.
  7. 7. Starter bacteria and type of cheese Now it is important how we are going to produce cheese. Now, depending on the type of cheese are added to the corresponding lactic acid bacteria. There are two types of bacteria used for this process: Mesophilic bacteria thrive at room temperature but die at higher temperatures. They are used to make mellow cheeses, such as Cheddar, Gouda and Colby. Thermophilic bacteria thrive at higher temperatures, around 55 °C, and are used to make sharper cheeses such as Gruyère, Parmesan and Romano.
  8. 8. Why are there holes in cheese ? Starter bacteria produce lactic acid, as well as aromatic compounds and carbon dioxide, which is responsible for the formation of cheeses mesh
  9. 9. Enzymes speed up coagulation Some cheeses are curdled only by acidity. For example, paneer cheese is made using lemon juice to curdle the milk and cottage cheese is made using mesophilic bacteria. However, for most cheeses, rennet (podpuszczka) is also added to the milk after a starter bacteria. Rennet is a mixture containing the active enzyme chymosin. Rennet speeds up the coagulation of casein and produces a stronger curd. It also allows curdling at a lower acidity, which is important for some types of cheese. Rennet is an extract from a calf’s stomach. It nowadays can be synthetically made
  10. 10. The 3rd step of cheesemaking – maturing of cheese. Further action of bacteria As cheese matures, bacteria break down the proteins, altering the flavour and texture of the final cheese. The proteins first break into medium-sized pieces (peptides) and then into smaller pieces (amino acids).
  11. 11. Other microorganisms in cheesemaking- fungus and yeats During maturing, some cheeses are inoculated with a fungus such as Penicillium. Inoculation can be either on the surface (for example, with Camembert and Brie) or internally (for example, with blue vein cheeses). During ripening, the fungi produce digestive enzymes, which break down large protein molecules in the cheese. This makes the cheese softer, runny and even blue.