Required practicle 4 - Food tests Flashcards
What is required for all food tests?
• Grind food sample with water to make paste
• Transfer to beaker, add more distilled water and stir so food dissolves
What is the test for starch?
• Add iodine
• Turns from orange to blue/black if present
What is the test for glucose?
• Add 2cm^3 sugar solution and10 drops benedicts solution
• Place test tube in beaker half-filled with boiling water and leave for around 5 minutes
• If present turns from blue to green/yellow/brick-red depending on amount present
What is the test for protein?
• Add biuret solution
• If present turns from blue to purple/lilac
What is the test for lipids?
• dont filter solution as lipid molecules can get stuck to filter paper
• add few drops of distilled water and ethanol then gently shake
• If present solution forms white cloudy emulsion
What is a hazard when testing for lipids?
• Ethanol is highly flammable
• So ensure no naked flames are present