microbes

• grow microorganisms in an industrial fermenter
• industrial fermenter:

  • a big tank used to control abiotic conditions to grow microorganisms
  • sterilise by passing steam through = kill any unwanted microorganisms
• cooling jacket = cold water around tank = keep enzymes at optimal temperature
• paddle stirrers = mix nutrients = prevent water or heat build up
• nutrient medium = gives microorganism nutrients for growth
• making bread with yeast:

  • yeast and sugar mixed with flour and water to form dough = yeast respires to produce bubbles of CO2 = make dough rise
• making beer with yeast:

  • anaerobic respiration of yeast feeding on maltose sugars from barley grains = creat ethanol and CO2 bubbles
• making yogurt with yeast:

  • lactobacillus added to warm milk = break down lactose to lactic acid = clots milk protein
• yogurt production:

  1. milk is pasturised at 85-90 degrees for 15-30 minutes = sterilise and kill bacteria
  2. milk is homogenised = break up fat blobs
  3. milk is cooled to 40-45 degrees and treated with lactobacillum bacteria
  4. fermentation - lactobacillus bacteria digest milk protein and break lactose into lactic acid
  5. pH drop when lactic acid reacts with milk protein to clot and thicken yogurt
  6. cooled to 5 degrees so bacteria stops growing