Food testing

• what is the name for the test for starch?


  Iodine test
• What is the name of the test for glucose?


  Benedict's test
• What is the name of the test for Proteins?


  Biuret test
• What is the name of the test for Lipids?


  Emulsion test
• What colour is iodine solution?

  Orange-Brown
• What colour does Iodine solution turn if starch is present?

  Blue-black
• What colour is iodine solution if the food doesn't contain starch?

  It will remain orange-brown
• What colour is Benedict's solution?


  Clear Blue
• What two steps must you remember when describing the Benedict test?

  Mash any solid food and heat in a water bath
• What colour does Benedict's solution turn if glucose is present?

  Green, yellow, orange or brick red precipitate - depending on amount of glucose
• If a Benedict test is negative, what colour will the solution be?


  It will remain clear blue
• What two solutions make up Biuret reagent?


  Sodium hydroxide and Copper sulphate
• How much do each solution do you add to mashed food for the Biuret test?


  An equal amount of sodium hydroxide to the food, and a few drops of Copper sulphate
• What colour are Sodium Hydroxide and Copper Sulphate?


  Colourless and Clear blue
• What colour appears if the test is positive?


  Lilac/Purple/Pink
• What colour is a negative Biuret test

  Remains clear blue
• In the emulsion test, how much food should you add to the test tube?


  3cm cubed
• How much ethanol should you add to the test tube with 3cm cubed of food in?


  An equal amount
• Once shaken in the test tube, what should any lipids do in the emulsion test?


  Dissolve in the ethanol
• What colour will ethanol be in a positive emulsion test?


  Cloudy/milky white emulsion
• What colour will the ethanol be after a negative emulsion test?


  Clear/colourless