Food Tests Flashcards
1
Q
What is the test for proteins?
A
- sample to be tested
- add biuret solution (pale blue)
- check if protein present (turns purple
2
Q
What is a positive result for protein?
A
- purple (lilac)
3
Q
What is the test for lipids?
A
- sample to be tested
- add ethanol
- pour into equal volume of water in another tube
- shake
- positive result -> cloudy white emulsion
4
Q
What is a positive result for lipids?
A
cloudy white emulsion
5
Q
What is a test for carbohydrates - Reducing sugar test?
A
- take sample
- add benedicts solution (blue)
- heat in a water bath at 85 degrees Celsius for 5 minutes
- positive result brick red precipitate
6
Q
What is a positive result for carbohydrates - Reducing sugar test?
A
- blue solution to brick red precipitate
7
Q
What is a test for carbohydrates - non-reducing sugar test?
A
- fresh sample
- add dilute hydrochloric acid
- place in water bath
- add a pinch of sodium hydrogen carbonate
- use PH paper to check PH is neutral
8
Q
What is a positive result for non-reducing sugars?
A
- Blue to brick red
- means sucrose was present in the original solution
9
Q
What is the test for starch?
A
- take sample
- add iodine solution
- starch present - blue/black
10
Q
What is the positive result for starch?
A
Yellow/brown to Blue/black
