Food Tests (Practical)
This lesson covers:
- How to prepare food samples for testing
- The Benedict's test for sugars
- The Iodine test for starch
- The Biuret test for proteins
- The Sudan III & emulsion tests for lipids
Which test is used to detect the presence of reducing sugars (i.e. small sugars like glucose)?
Biuret test
Benedict's test
Bartholomew's test
Bronchial test
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Does the Benedict's test require heating the sample in a water bath?
Yes
No
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Photos of Benedict's test
Benedict's solution itself in blue, but if reducing sugars are present then it will change colour depending on the concentration of reducing sugar.
Green indicates a low concentration of reducing sugar, orange indicates a medium concentration and brick-red indicates a high concentration.
What does iodine test for?
Glycogen
Starch
Proteins
Lipids
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Iodine solution is used to test for the presence of starch. If starch is present, which colour change takes place?
Blue to lilac / purple
Orange to blue-black
Blue to brick red
Orange to Pink
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To test for proteins we can use solution.
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Biuret reagent can be used to test for the presence of proteins. If protein is present, what colour change takes place?
Blue to lilac / purple
Blue to brick red
Orange to blue-black
Orange to Pink
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Which test is used to test for the presence of lipids?
Iodine test
Emulsion test
Biuret test
Benedict's test
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Emulsion test for lipids
cloudy / water / emulsion / acid / pink / ethanol
- Place your food sample in a test tube.
- Add 2cm3 of .
- Shake.
- Add 2cm3 of distilled .
- If a emulsion forms then lipid was present.
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