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i rely hope this is not too messyCan some one please share the food test procedures and will we have a graticule scale and all that?
biuret test : add an equal amount of NaOH to a solution of the food, mix carefully.
add a few drops of 1% CuSO4, do not shake the mixture.
a PURPLE/MAUVE COLOR is a positive result: protein is present.
iodine test:
1. If the food to be tested is liquid, go to 2. If the food to be tested is solid, make an extract. Grind crush or chop a
small amount and put into a test tube to a depth of about 2cm. Add a similar amount of distilled water and stir with
a glass rod. Allow to stand for a few minutes.
2. Draw up some of the clear liquid into a pipette and then either transfer it into another test tube or put drops onto
a white tile.
3. Add on drop of (brown) iodine solution on the tile and look for a color change. A blue-black color indicates
the presence of starch.
benedicts' test :for reducing sugar
. Addabout 5cm3of the reagent to a small amount of sample in a testtube.
.Stand the test tube in boiling water for a few minutes.
A colour change through green to yellow, brown and finally to red indicates the presenceof reducingsugar
for non reducing sugar :
01.If the sample isn't already in liquid form grind it up in water.
2. Add 2cm3(cubed) of the food sample to a test tube with 2cm of benedict's reagent
3. gently) boil in a water bath for 5 mins
4. If a NON-REDUCING sugar is present then the solution will remains BLUE
5. In this case another 2cm3 of the food sample to 2cm3 of (dilute) hydrochloric acid in a test tube(as the hydrochloric acid hydrolyzes the disaccharide into its monomer constituents .i.e. sucrose --> glucose + fructose)
6. (Slowly) add sodium hydrogencarbonate to the test tube(to neutralise the hydrochloric acid as Benedict's reagent can't work in acidic conditions)
7. Now re-test the solution by heating it with the 2cm3 of Benedict's reagent for 5 mins, this time the solution should turn from blue to orange-brown/brick red because reducing sugars are present(.i.e. glucose and fructose)due to the hydrolysis of the disaccharide (sucrose)