B3.3 Food Tests And The Chemistry Of Food Flashcards
What chemical is used to test for starch?
Iodine
What chemical is used to test sugar?
Benedicts solution
What is the chemical used to test for lipids (fats)?
Ethanol
What chemical is used to test for proteins?
Biuret solution
What colour is iodene and what colour does it turn into when starch is present?
Orange-red —> blue black
What colour is benedicts solution and what colour does it turn into when sugar is present?
Light blue —> green (if less sugar) to brick red (if alot sugar)
What colour is ethanol and what colour does it turn into when lipids are present?
Colourless —> cloudy emulsion
What colour is biuret and what colour does it turn into when protein is present?
Blue —> lilac purple
How would you prepare the food samples before a food test?
- Break up the food using a pestle and mortar
- Transfer to a test tube and add distilled water
- Mix the food with the water by stirring with a glass rod
- Filter the mixture using a funnel and filter paper, collecting the solution
Explain how to use benedicts solution to find out if sugar is present
Add a couple drops if benedicts solution to your pre-prepared sugary solution and put the test tube in hot water(anout 80 degrees) for 5 min. Then check for any colour changes.
What are proteins made up of?
Long chains of differents amino acids
Why are proteins needed in the body?
- Proteins are needed in the diet for growth and repair of body tissues (e.g. bone ,muscle etc).
What are the three different types of carbohydrates?
- Sugar
- Starch
- Fibre
What enzyme breaks up large starch molecules and what does it produce?
Carbohydrase breaks down large starch molecules to produce sugar molecules.
What enzyme breaks up protein molecules?
Protease breaks down protein molecules to produce amino acid moleculesm
What are fats/lipids made of (structure)
They are made up of a glycerol molecule joined to three fatty acids.
What are fats for in our body?
Fats provide energy and insulation for the body.
Where are fats stored?
They are stored under the skin and around the organs as adipose tissue.
What enzyme digest fatty/lipid molecules and into what?
Lipase breaks down lipid molecules into fatty acid molecules and glycerol molecules.
What is amylase an example of?
Amylase is an example of a carbohydrase enzyme.
Where is amylase stored?
Mouth and small intestine.
Where is protease stored?
Stomach, small intestine
Where is lipase stored?
Small intestine
What does fibre do for us?
Aids digestion and prevents constipation.
Why do we need carbohydrates?
Good for providing energy
What can high cholosterol lead to?
Can lead to narrowing the arteries - corinary heart disease - stroke
- need for stent
- need to take statins
