Unit 2 Section 4.3 Microorganisms and Food

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  • Micro-organisms  and Food
    • Micro-organisms in food production
      • microorganisms such as bacteria, yeast and other fungi are used in the production of many foods and drinks.
      • Some microorganisms can convert sugar into other substances that humans can then use for food production
      • Advantages
        • There are many advantages of using microorganisms to make food:
          • Populations of microorganisms grow rapdly under the right conditions, so food can be produced quickly
          • Microorganisms can grow on a range of inexpensive materials
          • Their environment can be artifically controlled - so you can potentially grow food anywhere and at any time of the year
          • Optimum conditions for growth are easy to create
          • Some of the food made using microorganisms often last longer in storage than the raw product they're made from
      • Disadvantages
        • There's a high risk of food contamination the conditions created to grow the desirable microorganisms are also favourable to harmful microorganisms. they could cause the foods produced to spoil or if eaten, cause illnesses such as food poisoning
        • The conditions required to grow microorganisms can be simple to create, but small changes in temperature or pH can easily kill the microorganisms
    • Food Spoilage
      • Food spoilage is the detoriation of a foods characteristics
      • it can be caused by the growth of unwanted microorganisms, such as bacteria and yeast
      • As the microorganisms multiply they secrete enzymes which break down molecules in the food
      • Some microorganisms may also produce waste products which contribute to food spoilage and could cause food poisoning if the food is eaten
      • Food poisoning can affect anyone, but some parts of the population are particularly susceptible to it
    • Preventing Food Spoilage
      • Salting
        • is simply adding salt to foods. salt inhibits the growth of microorganisms by interfering with their ability to absorb water
      • Adding Sugar
        • like salting sugar also inhibits the growth of microorganisms by interfering with their ability to absorb water by osmosis
      • Freezing
        • freezers keep foods below - 18 degrees centegrade. this slows down enzyme controlled reactions taking place in micro-organisms and freezes the water in the food, so the micro-organisms can't use it. freezing can preserve foods for many months
      • heat treatment
        • heat Treatment involves heating food to a high enough temperature to denature enzymes and kill any microorganisms present
      • Irradiation
        • Irradiation involves exposing foods to radiation, this treatment kills any micro-organisms present and can extend shelf life considerably
    • Pickling in Vinegar
      • Vinegar has a low pH. this denatures enzymes in microorganisms, preventing the enzymes from functioning properly and inhibiting the microorganisms growth. vinegar is used to pickle foods like onions


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