SB1f - Testing Foods Flashcards
What complex carbohydrate do bananas contain?
Starch
What is a chemical reagent?
A chemical that allows you to identify when a certain substance is present
What solution is used to test for starch and what colour does it turn?
Iodine becomes blue or black and no starch means the iodine will stay orange
What solution tests for reducing sugars and what colours does it go?
Benedict’s solution stays blue when there’s no reducing sugar, green when there’s a little and becomes redder as more reducing sugar is present
What must you do to Benedict’s solution and the food solution to see results?
Place it in a hot water bath for a few minutes
What kind of reaction occurs between Benedict’s solution and reducing sugars?
Reduction reaction
How can you test for protein?
Doing the biuret test
What is the buriet test?
Where potassium hydroxide is mixed with a solution of food and the two drops of copper sulphate solution are added.
What colour does the biuret test start and what does it become if what substance is present?
Starts pale blue and turns purple if protein is present
How can you test for lipids?
Ethanol emulsion test
What is the ethanol emulsion test and what is it for?
Where food is mixed with ethanol, shaken then poured into water and shaken. Lipids dissolved in the ethanol float to the surface when left to stand.
What does a calorimeter measure?
The amount of energy in food by burning it
How can the amount of energy transferred from the burning food to the water be calculated on a calorimeter?
By looking at the increase in water temperature
