Tests in Biochemistry

Starch:

• 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

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