Cheese making - Bacteria

• Lactobacillus bacteria are fed on lactose (sugar in milk) to produce lactic acid (Lactose → lactic acid)
• Commercial process:

  • Milk is pasteurised, heated to 95°C for 20 seconds to kill natural bacteria, it is also homogenised (fat droplets evenly distributed)
  • Lactobacillus bacteria are added to produce lactic acid, once acidified milk is mixed with rennet (contain enzyme rennin, chymosin) which coagulates milk protein in a solid (curd); curds and whey (liquid part) are separated
  • Cottage cheese (curds are packaged and sold), harder cheese (curds cooked in whey and strained through cheese cloth, may be pressed/matured) and Whey (in animal feeds)