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Biological Molecules: Tests (Part- 3) - Coggle Diagram
Biological Molecules: Tests
(Part- 3)
Test for starch: Polysaccharide
Extract and add iodine
A positive test would give a colour change to
blue- black colour
.
Test for reducing sugars (Monosaccharides E.g. Glucose)
Add
Benedict's solution
and place in a
warm- water bath.
Positive test would give colour changes from
clear blue to cloudy green, then yellow and finally red precipitate.
The red precipitate is Copper (I) oxide.
Food sample should be
extracted with water
.
Test for protein (Biuret test)
Extract food sample with water.
Add
biuret's reagent
(A solution of
sodium hydroxide + Copper sulfate
).
Positive test would indicate a
purple colour.
Test for Fat
Extract food sample with ethanol, filter it and pour the filtrate into water.
Positive test is
when added to water, a milky- white emulsion
will form.
Test for vitamin C
Add DCPIP solution to food sample
(extracted with water if solid).
A positive test would be that the
solution would have turned colourless.
If it takes more time for the DCPIP to turn colour, it means that less vitamin C is present.