MICROORGANISMS AND FOOD SPOILAGE

microorganisms and food spoilage (part 3/3)

hienemann texbook use only

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  • Created by: EClou
  • Created on: 22-01-15 23:05
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  • MICROORGA-NISIMS AND FOOD SPOILAGE
    • Ways M. spoil our food
      • 1. Visible growth of Ms on food e.g. Penicillium
      • 2. Ms use an external digestion process
      • 3. Bacterium Clostridium Botulinum produces toxin-botulin - causes botulism, 1ug can kill
      • 4. Ms in food can cause infection e.g. salmonella
    • prevention of spoilage
      • 1. cooking
        • denatures enzymes
      • 2. Pasturising
        • heating(72oC) and rapid cooling(4oC) kills Ms
      • 3. Drying/ Salting/ Sugar coat
        • dehydrate Ms by osmosis
      • 4. Smoking
        • smoke contains antibact. chems
      • 5. Pickling
        • acid denatures enzymes
      • 6. Irridation
        • ionising radiation disrupts DNA- kills
      • 7. Cooling/ Freezing
        • retard enzyme activity to slow growth and reprod.
      • canning/ vacuum packing/ plastic/paper packaging prevents aerobic resp.
    • Untitled
    • Foods made from Ms
      • Yoghurt
        • Lactobacillus uses lactose sugar in milk to make lactic acid
      • Cheese
        • rennet enzyme added-Lactobacillus causes curd
        • can be flavoured e.g. by Penicillium
        • Untitled
      • Bread
        • yeast -anaerobic resp-CO2-rise
      • Alcohol
        • yeast -anaerobic resp-CO2-rise
      • Quorn a.k.a single-celled protein
        • mycoprotein made by fungus
    • advantages
      • no welfare issues
      • good source of protein for veggies
      • production can be increased/ decreased according to demand
    • Disadvantages
      • protein must be purified to ensure its not contaminated
      • people may not wanna eat fungal protein/food grown on waste
      • isolation- Ms grown in huge fermenters and must be isolated from host material

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