Food Tests Flashcards
What do you use to see if there’s starch?
What’s the method?
What’s the results?
Iodine test
Add several drops of iodine solution to solid food or liquid
It turns yellow/brown to blue/black
What do you use to see if there’s sugar?
What’s the method?
What’s the results?
- Benedict’s test
- Dissolve food in 1cm3 of water using a pestle and mortar
Add to a boiling tube
Add 2cm3 of Benedicts solution
Place in a boiling water bath for 2 to 3 minutes. - Turns from blue to green to brick red
What do you use to see if there’s protein?
What’s the method?
What’s the results?
Biuret test
Dissolve food in 1cm3 of water using a pestle and mortar
Add to a boiling tube
Add 1cm3 of dilute sodium hydroxide and copper sulphate
Shake gently
Starts a pale blue and turns to lilac/purple/violet
What do you use to see if there’s fat?
What’s the method?
What’s the results?
Emulsion test (ethanol)
Cut food into very small pieces
Place in a boiling tube
Add 3cm3 ethanol
Shake and leave to settle
Half fill a 2nd test tube with water
Carefully add drops of the solution from the 1st test tube to the water.
Water will have a white emulsion ring at the top of the test tube.
Turns from colourless to cloudy/milky
How many kilojoules does 1 gram of protein give you
17 kilojoules
How many kilojoules does 1 gram of fat give you
38 kilojoules
How many kilojoules does 1 gram of carbohydrates give you
17 kilojoules
What is the equation for energy in food
Energy in 1 gram of food= rise in temperature X volume of water X 4.2
What type of foods would have more energy in them
Foods that are high in fat
What are the steps in the experiment to find out how much energy is in food?
- Measure 20 ml of water into a boiling tube
- Clamp the boiling tube to a stand and stir the water with the thermometer and take it’s temperature
- Weigh 1gram of the food
- Place the food into a wire basket held underneath the boiling tube
- Roast the food in a Bunsen flame until it starts to burn
- Turn off the Bunsen
- As the food burns the water will heat up
- Once the food has stopped burning , stir the water and record the temperature
How many kilojoules of energy does an average man need each day?
10,470 kJ per day
How many kilojoules does an average woman need each day?
8370 kJ per day
What is starch found in and what’s it needed for
Carbohydrates, needed for energy.
What is glucose found in and what’s it needed for?
Sweets and fizzy drinks.
Energy quickly.
What are vitamins found in and what are they needed for?
Vegetables and fruits. Needed to maintain health.
What is fibre needed for?
Keep food moving around the gut.
What is fat found in and what’s it needed for?
Found in nuts, oils, butter , cheese.
Needed to provide energy.
Where is protein found and what’s it needed for?
Found in meat. Needed for growth and repair of cells.
What are minerals found in and what are they needed for.
Found in milk, red meat, leafy green veggies. Needed to maintain health.
