Starch Use

• What happens during the gelatinisation of starch?

  1. Starch is heated in water and it swells because it absorbs water and thickens- this forms wallpaper paste/ custard.
  2. When it cools, bonds form between molecule, making the substance stiff. This can be reversed by the addition of water.
• How is starch foam produced?

  1. maize is heated and starch gelatinises.
  2. hydrogen bonds that hold the starch together break.
  3. granules swell as they absorb the water. there is little water in the seed so gelatinisation occurs at a high temperature.
  4. as starch swells, pressure increases in the seed, making the coat rupture.
  5. superheated water in the seed turns to steam, forming expanded foam
• Advantages of biofuels:

  • no contribution to global warming- carbon neutral
  • renewable- plants won't run out
  • doesn't produce non-biodegradable waste
• Disadvantages of biofuels:

  • a lot of energy used during transportation- can produce pollution.
  • source of the plant products
• Why is bioplastic more sustainable than oil-based plastic?

  Biodegradable- can be decomposed when disposed of, therefore it prevents pollution