Thought I would do a little synopsis of all the biochemical tests we need to know for foods!
Proteins: Add sodium hydroxide to make solution alkaline, copper (II) sulfate solution, positive result means it turns from blue to purple.
Reducing sugars: Add Benedict’s Reagent and heat, positive result means turns from blue to brick red.
Non reducing sugars: Boil with hydrochloride acid to break down into monosaccharides, neutralise by adding sodium hydrogencarbonate, then repeat test for Reducing sugars. Should again turn from blue to brick red.
Starch: Add iodine dissolved in potassium iodide. Positive result means colour change from orange to blue/black colour.
Lipids: Shake the test substance with ethanol for about a minute, pour into water. Lipid will show up as a milky emulsion.
Hopefully that clarifies things a bit! If not then next time I will try harder :’) have a great day! Stay strong people!