biochemical tests Flashcards
1
Q
name of test for reducing sugars
A
benedicts ONLY
2
Q
name of test for non-reducing sugars
A
benedicts test + with other steps
3
Q
name of test for starch
A
iodine
4
Q
name of test for proteins
A
biurets
5
Q
name of test for lipids
A
emulsion test
6
Q
colour change with benedicts (reducing sugars)
A
blue -> brick red
7
Q
colour change with biurets
A
blue -> purple
8
Q
colour change benedicts AT THE END of non-reducing sugars
A
blue -> brown/orange
9
Q
colour change with emulsion test
A
cloudy - white layer
10
Q
method for iodine test
A
- Add 2cm3 of sample
- Add 2 drops of iodine
11
Q
method for reducing sugars
A
- Ground sample into water
- Add benedicts solution
- Heat in water bath
12
Q
colour change with iodine
A
orange -> blue/black
13
Q
method for biurets
A
- Ground sample into water and place in test tube
- Add equal volume of NaOH at room temp
- Add a few drops of CuSO4 (very very dilute!!!) and mix gently
14
Q
method for emulsion test
A
- Add 2cms of sample and 5cm3 of ethanol
- Shake thoroughly to dissolve lipid
- Add 5cm3 of water and shake
- Milky/white emulsion should be seen
15
Q
method for non-reducing sugars
A
- Ground sample to water and add 2cm3 of sample to 2cms of benedicts
- heat in water bath for 5 minutes
- Add 2cms food sample to 2cm3 of dilute HCl, place in water bath for 5 mins
- add sodium hydrogencarbonate to neutralise pH (test with pH paper)
- Re-test with 2cms benedicts in boiling water bath