Tests in Biochemistry


Tests for Carbohydrates


  • To show the presence of starch add iodine
  • If starch is present the solution turns from yellow to blue-black

Reducing Sugars:

All monosaccharides and some dissacharides fall under this category:

  • Heat with Benedict's Solution
  • The solution changes colour from blue to a brick red precipitate

Non-Reducing Sugars:

  • Boil with HCl
  • Neutralise with NaHCO3 (sodium carbonate)
  • Carry out reducing test again
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Test for the presence of Proteins and Lipids

Test for Proteins: Biuret test

  • Add Biuret reagent
  • If protein present the solution changes colour from blue to purple

Test for Lipids: Emulsion Test

  • Add ethanol
  • Pour into water
  • If lipid is present then a white emulsion is formed on the top
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