Improving food production
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Improving food production






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    Improving food production Improving food production Presentation Transcript

    • Improving Food production
    • Objectives
      • Describe how the use of fertilisers and pesticides with plants and the use of antibiotics with animals can increase food production
      • Describe the advantages and disadvantages of using microorganisms to make food for human consumption
      • Outline methods used to prevent food spoilage by microbes
      • in many countries farming has become more intensive (since world war 2)
      • fertilisers/pesticides used
      • animals fed supplements and antibiotics
      • recent backlash
      • people prepared to pay more for organic food
    • fertilisers
      • ammonium nitrate
      • plants need ammonium ( NH 4 + ) and nitrate (NO 3 - ) ions
      • expensive
      • soil tested using GPS to see if needed – can be applied in exact quantities
      • too much fertiliser not only damages environment and is costly but actually reduces yield by reducing water potential in soil
      • precision not possible using manure
    • Classwork/Homework questions
      • saq 8, 9, 10 p158-159 cambridge
    • pesticides
      • insecticides/fungicides
      • DDT – accumulates in food chain. broad spectrum . banned. malaria
      • several applications a year needed
      • resistance can develop
      • traces left on food
    • antibiotics
      • intensively farmed animals
      • more susceptible to disease
      • treatment increases growth rates
      • may destroy bacteria in gut that would slow growth
      • widely used with pigs and chickens
      • risk of resistance to antibiotics evolving in bacteria if used too widely,
    • How can microbes spoil our food?
      • Visible growth on bread, cheese etc - Grows for a few days before it is noticible – Mucor – black, Penicillium - blue green
      • Sweet smell (bananas) – indicates enzymes are releasing sugars from carbohydrate – food will become mushy
      • Can cause infection – Salmonella , in chicken – also Clostridium botulinum and E.Coli
    • preventing food spoilage by microbes
      • Refrigeration – slows enzyme activity of microbes
      • Salting/sugaring/drying - dries the food by osmosis
      • Pickling - acid denatures microbe enzymes
      • freezing – lack of water prevents growth of microbes
      • pasteurisation/UHT - kills harmful microbes
      • Irradiation- disrupts DNA of microbes
      • vacuum sealing/canning- prevents air reaching food (needed for microbial aerobic respiration)
      • Name a different foodstuff that is preserved by each method
    • Using microbes to make food
      • Yogurt- milk turned sour by Lactobacillus bacteria- uses lactose sugar in milk to make lactic acid. This also thickens the milk proteins
      • Cheese - from curdled milk. Lactobacillus
      • Bread- uses yeast ( Saccharomyces ) to rise. The carbon dioxide produced provides the bubbles
      • Alcohol- a by product of anaerobic respiration- uses strain of yeast called Saccharomyces Carlsbergensis. This respires (ferments) on sugars in grapes( glucose /fructose) to make wine or malted barley ( maltose sugar) to make beer
    • mycoprotein (QUORN)
      • myco – fungus
      • Fusarium venenatum /graminearum
      • Single cell protein (SCP)
      • Advantages
        • Similar texture to meat
        • Faster growth than meat
        • All essential amino acids, lower in fat , no cholesterol
        • Production can easily be changed with demand
        • Can be grown all year round
      • Disadvantages
        • taste
        • Can be grown using waste as a substrate material such as paper and whey( curdled milk from which curds are removed)
        • Protein needs to be purified to avoid contamination
        • Care needs to be taken to avoid microbial infection of product
    • Homework Questions
      • Why should frozen food never be thawed and then refrozen?
      • Describe the effects of these temperatures on bacterial growth and activity (all degrees celsius): -12, 4, 25, 37, 50, 65, 100, 120
      • Explain how osmosis can help keep food fresh
      • What is the difference between milk that is pasteurised and UHT?