Food Tests - Detecting Key Nutrients

Testing for reducing sugars is dead simple - just mix 2cm³ of your food sample with Benedict's reagent and heat for 5 minutes. If it stays blue, there's no sugar present, but watch for exciting colour changes from green through yellow and orange to red that show increasing sugar levels.

Non-reducing sugars need a bit more work since they're trickier to detect. You'll need to add hydrochloric acid first to break them down, then follow the same Benedict's test procedure. This extra step is crucial because sugars like sucrose won't react without being broken apart first.

The Biuret test for proteins gives you a brilliant purple colour when proteins are present. Mix your sample with sodium hydroxide, add a few drops of copper(II) sulphate, and you're sorted - blue means no protein, purple means jackpot.

Top Tip: Always start with the iodine test for starch - it's the quickest and most dramatic, turning blue-black instantly if starch is present!

Starch testing couldn't be easier with just iodine solution, whilst lipid detection uses the emulsion test with ethanol and water to create a cloudy white mixture that proves fats are lurking in your sample.