SB1f - Testing foods Flashcards

1
Q

What test do we use when we are testing for starch and state the colour change.

A

Iodine test - use iodine solution - from yellow - black

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2
Q

What test do we use when we are testing for sugars/carbohydrates and state the colour change.

A

benedicts solution + heat it

From blue -> green -> orange -> red
increasing in concentration

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2
Q

What test do we use when we are lipids/fats for starch and state the colour change.

A

emulsion test - use ethanol - colorless to cloudy white

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2
Q

What test do we use when we are testing for Proteins and state the colour change.

A

Biuret - Turns from blue to purple

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3
Q

State what is meant by a Qualitative?

A

Qualitative tests show whether a substance is present or not but not the amount

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4
Q

State what is meant by a Quantitative?

A

Quantitative tests give the amount of substance that is present

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5
Q

What are the risks of Food tests?

A

Risks
* Potassium hydroxide can be harmful to skin and eyes.
* Hot water can burn skin

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5
Q

What safety measures should be taken?

A

Safety measures
* Wear eye protection.
* Do not taste any of the foods.
* Take care with hot water.
* Wash off any splashes immediately.

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6
Q

What is a colorimeter?

A
  • 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.
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6
Q

State the steps needed to measure the energy in food?

A

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

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