Improving food production


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Improving food production

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