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1st 2023, biotechnology.ppt

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1st 2023, biotechnology.ppt

  1. 1. Yeast Bread
  2. 2. What part does each play in the making of bread?  GLUTEN – provides dough with elasticity and strength.  YEAST – makes dough rise and gives it it’s porous texture Under developed gluten Developed gluten
  3. 3. Define  HYDRATION – To Add water  DEHYDRATION – To remove water
  4. 4. Hydration of dry active yeast  Dry active yeast must be hydrated with warm water, not too hot.  The proper temperature helps the yeast give off the correct amount of carbon dioxide. Too Cold 85° If the water is too hot, the balloon doesn’t inflate at all!
  5. 5. In order to grow yeast needs:  Moisture -- Milk or water  Warmth -- @ 110° F  Food -- sugar OR
  6. 6. How does each affect the growth of yeast?  Sugar – Provides food for the yeast to grow.  Salt – Controls the growth of the yeast.
  7. 7. Four main processes for making yeast dough: 1. MIXING 2. KNEADING & RISING 3. SHAPING & RISING 4. BAKING mixing Kneading and rising
  8. 8. Shaping dough Baking
  9. 9. Yeast Growth  As yeast grows CARBON DIOXIDE develops causing the dough to rise. Once multiplying begins
  10. 10. How do you know the bread has risen enough?  Should double in size  Push two fingers into the dough, if the holes remain but the top stays smooth and satiny.
  11. 11. Why is the milk scalded then cooled?  To destroy enzymes that make dough sticky  To allow yeast to grow at optimum temp. – Too hot of temperature will kill the yeast!
  12. 12. What does kneading do?  Develops the gluten so the dough will stretch and expand. 1 2 3 4 How to knead
  13. 13. When judging bread look for:  Appearance – Uniform golden brown – Smooth rounded top – Creamy white inside  Crumb – Cut surface is moist and springy to touch
  14. 14. Continue …  Texture – Fine grain – Porous  Flavor – Sweet, nut-like wheaty taste
  15. 15. Ways to shape dough Cloverleaf Rolls Crescent Rolls Parker House Rolls
  16. 16. Snails Twists Tea rings Pretzels Cinnamon Rolls
  17. 17. Yeast is used for making alcohol. Yeast is a single-celled fungus Yeast cells feed saprophytically. This means they secrete enzymes from their cells. The enzymes digest the food on which the yeast is living, breaking down large molecules into small ones. The small molecules then diffuse into the yeast cell.
  18. 18. 'Wild' yeast grows in many different places. It usually grows on foods which contain sugar, such as fruit. When we grow yeast, we need to provide it with the types of food which it needs. It is usually grown in a solution containing carbohydrate - usually in the form of sugar and minerals, including ammonium ions. Each yeast cell absorbs the sugar and minerals, and uses some of them to grow. When the cell gets to a certain size, it produces a new cell by budding. Yeast cells reproduce fastest when the tem- perature is quite warm, around 40 °C.
  19. 19. People have been using yeast for thousands of years to make alcohol. If yeast is added to a sugar solution, it absorbs some of the sugar into its cells. It then uses this sugar in respiration. Usually, the yeast respires anaerobically. When it does this, it converts the sugar to ethanol (a type of alcohol) and carbon dioxide. This process is called alcoholic fermentation. 'Fermentation' is a name for any type of respiration which makes a product other than carbon dioxide and water. The equation for alcoholic fermentation is: Glucose → alcohol + carbon dioxide + energy
  20. 20. Many different alcoholic drinks are made in this way Beer is made by providing the yeast with the sugar maltose, obtained from germinating barley seeds. Usually, hops are added as well, to give a bitter flavour to the beer. Wine is made by providing the yeast with sugar from grapes.
  21. 21. Yeast is used for making bread. When yeast respires, it produces carbon dioxide. If this happens inside a dough made from flour and water, the bubbles of carbon dioxide get trapped in the dough, and make it rise. This is how bread is made. The dough is made using flour made from cereal grains, usually wheat. The flour contains starch, amy- lase and protein.
  22. 22. The starch is the energy source for the yeast. The amylase digests the starch to sugar, so that the yeast can absorb it and use it in respiration. Some bread flours have extra amylase added to them to speed up this process. The amylase does not begin acting on the starch until water is mixed with the flour. The protein is important for the texture of the bread. The most important protein in bread flour (apart from the amylase!) is called gluten. This forms sticky, threads as the yeast works on the dough.
  23. 23. This helps to trap the bubbles of carbon dioxide, and makes the dough rise well. Farmers who want to sell their wheat for bread making choose varieties which are known to produce grains containing a lot of gluten. To make bread, yeast, sugar, flour and water are mixed together to make a dough, which is then left in a warm place to rise. The dough is then mixed again, and made into the shapes of the loaves to be made. It is left to rise again, and then baked. The high tempera- tures kill the yeast, break down the alcohol which it has made, and alter the remaining starch and gluten to make a firm textured bread.
  24. 24. Use of enzyme in biological washing powders Biological washing powders contain protease and lipase to remove protein stains and fat/grease from clothes. The enzymes break down proteins or fats on the fabric, forming water-soluble substances that can be washed away.
  25. 25. Example: Blood contain the red protein Haemoglobin (Hb). The Proteases in biological washing powder break Hb molecules into smaller molecules, which are not coloured and which dissolve in water and can be washed away. This makes the washing powder more effective than detergent alone, especially at lower temperatures. This save energy (no need to boil water), but if the temperature is too high, the enzyme will be denatured.
  26. 26. Fermenter or bioreactor refers to a device that provides all the basic necessities important for biological product extraction. A fermenter contains different devices that help to maintain the environmental factor inside it which in turn leads to the production of biological products. Therefore the main objective of a fermenter is to maintain a controlled environment that supports the growth of the bacteria or any other organism.
  27. 27. here are several important factors that need to be accurate to design a fermenter. Those factors are following •The vessel should be well equipped to maintain aseptic conditions inside it for a number of days. •Aeration and agitation are important for the production of biological metabolites. However, controlled agitation is required to prevent any damage to the cells. •It should be less expensive in terms of power consumption. •Temperature is an important environmental factor required for microbial growth. Therefore, a temperature control system is required.
  28. 28. •Optimum pH is important for the growth of the organism; therefore, the fermenter must be equipped with a pH controller. •The fermentation of a huge culture is a time-consuming process. It needs to be contamination-free until the process is complete. Apart from that, it is also important to monitor the growth rate of the organism. Therefore, an aseptic sampling system is needed to design a fermenter.
  29. 29. •The fermenter vessel should be designed properly to minimize the labor involved in cleaning, harvesting, etc. •It should be designed in such a way that it reduces evaporation. •The vessel needs to be equipped with a smooth internal surface to support adequate mixing.