Fats

• Fats are composed of carbon, hydrogen and oxygen
• Fats are composed of one glycerol molecule with 3 fatty acids. Different types of fatty acid affect the properties of the fat
• Plasticity?

  The ability of a fat to soften over a range of temperatures and be shaped and spread with light pressure
• Shortening?

  The ability of fats to shorten the length of gluten molecules in pastry
• Emulsification?

  Fats can keep either drops of oil or fat-suspended in a liquid and prevent them from separating out, or keep drops of water suspended in an oil or fat and prevent them from separating out
• Examples of oil in water emulsifications: mayo

  Examples of water in oil emulsifications: salad dressing
• Aeration?

  The ability of some fats to trap lots of air bubbles when beaten together with sugar. They can do this because they have good plasticity
• Saturated fatty acids are harder and therefore have less plasticity. Unsaturated fatty acids are softer and therefore have more plasticity
• Emulsifiers are added to create a bond between the water and fat molecules as they don't naturally mix permanently together. It creates an emulsion where it stops the water and oil from separating
• Lecithin works by creating bonds between hydrophilic and hydrophobic molecules
• Between 160 and 250 degrees celsius (depending on the oil), a blue coloured haze appears, followed quickly by the smoke point. When an oil reaches this point, the oil will rapidly reach flash point and burst into flames
• Why does margarine have more plasticity than lard?

  • Margarine has more unsaturated fatty acids
  • This makes it softer as it's less solid, increasing plasticity by being able to soften, shaped and spread better as it can melt at a lower temperature
• What is the role of egg yolks in a hollandaise sauce?

  • Egg yolks contain lecithin
  • Hollandaise sauce contains egg yolks
  • The lecithin has molecules with hydrophilic and hydrophobic ends and this holds the oily and water parts of the sauce together, creating a stable emulsion as the oil and water don't separate