Chapter 3: Biological molecules

• carbohydrate is classified into three main groups:

  monosaccharides, disaccharides, and polysaccharides

  • Monosaccharides are simple sugars
  • Disaccharides are double sugars
  • Polysaccharides are complex sugars
• Glucose + Glucose = Maltose​

  Glucose + Fructose = Sucrose​
• How to do the Benedict's test? (reducing sugars test)

  • Add a 2cm^2 of food sample
  • Add a 2cm^2 of Benedict's solution
  • Shake and place in boiling water bath for 2-3mins
• Benedicts solution colours and meanings:

  • Blue=none
  • Green=trace
  • Yellow=low
  • Orange=moderate
  • Brick Red=high
• How to test for starch?

  • add a few drops of iodine on a solid food sample
  • if it turns blue it has starch if it stays brown it doesn't have starch
• How to do ethanol emulsion test?

  • Add 2.0 cm3 of ethanol to a few drops of liquid sample in a test tube. ​
  • Shake the contents of the tube vigorously. ​
  • Decant the contents to another test tube containing 2.0 cm3 of water and shake the mixture.​
• How to do biuret test?

  • Add 2.0 cm3 of Biuret solution to 2.0 cm3 of food sample into a test tube.​
  • Shake the mixture thoroughly.​
  • Observe for colour change.

  if it turns blue there isnt protein

  if it turns purple there is proteins
• What is the main role of carbohydrates?

  Energy source