SB1f - Testing foods Flashcards
What test do we use when we are testing for starch and state the colour change.
Iodine test - use iodine solution - from yellow - black
What test do we use when we are testing for sugars/carbohydrates and state the colour change.
benedicts solution + heat it
From blue -> green -> orange -> red
increasing in concentration
What test do we use when we are lipids/fats for starch and state the colour change.
emulsion test - use ethanol - colorless to cloudy white
What test do we use when we are testing for Proteins and state the colour change.
Biuret - Turns from blue to purple
State what is meant by a Qualitative?
Qualitative tests show whether a substance is present or not but not the amount
State what is meant by a Quantitative?
Quantitative tests give the amount of substance that is present
What are the risks of Food tests?
Risks
* Potassium hydroxide can be harmful to skin and eyes.
* Hot water can burn skin
What safety measures should be taken?
Safety measures
* Wear eye protection.
* Do not taste any of the foods.
* Take care with hot water.
* Wash off any splashes immediately.
What is a colorimeter?
- A calorimeter is a machine used in the process of calorimetry. Small samples of
material are placed in the machine which burns them. The energy given off
when the material burns is measured.
State the steps needed to measure the energy in food?
Steps:
1.Take a fixed mass of your chosen food (e.g. 10g)
2.Put in on a mounted needle
3.Burn it under a test tube with a fixed volume of water (e.g. 20cm3)
4.Record the temperature of the water
5.Repeat
6.Calculate energy given using the formula