Food test practices (NEED TO KNOW FOR GCSE’s)

Alternative transcript:

reducing sugars present then the solution should change to green, yellow or even brick red depending on the concentration. lodine test (starch) •Starch is a carbohydrate but it's a much larger and more complex molecule. Take Scm³ of your food sample in a test tube 2 Add a few drops of jodine solution in the test tube This will turn the solution a browny - orange colour Give a gentle shake If the sample did contain starch the solution would change from that browny - orange colour to a blue - black colour. Biuret test (proteins) Ondd 2cm³ of food sample in a test tube.. Add 2cm³ of Bid ret solution to your sample This solution will turn to blue 3 Give a gentle snake if the sample did contain protein ine solution would change from blue to pink or purple EDEXCEL Content ONLY: instead of just adding directory agent (biuret solution). Add potassium hydroxide followed by copper sulfate Sudan III (3) test (lipids) Not filtered QAdd 5cm³ of food sample in a test tube Add 3 drops of the sudan 3 stain solution to the test tube. Gently shake it. if the lipid was present it should get stained by the sudan 3 solution As the lipid seperates from the water (not soluble) you'll see there's a bright red layer at the top. EDEXCEL Content ONLY: Emulsion test (upids) 0 Take your food sample in a test tube. Add 2cm³ ethand 6 Shake it vigorously Add 2cm³ distilled water • If it goes a cloudly while colour it means that lipid was present. 6 If there isn't any cloudy white colour then there wasn't any lipid.