This document describes a series of tests to identify unknown carbohydrates. It outlines tests using iodine, Benedict's solution, Barfoed's solution, and Seliwanoff's reagent that can identify polysaccharides like starch through deep blue or red colors, and determine if a sample is a reducing or non-reducing mono- or disaccharide through the presence or absence of red precipitates or scum. Follow-up tests like hydrolysis and osazone formation further characterize a sample as glucose or fructose.

2. Unknown carbohydrate solution
Molisch’s test – reddish violet ring
Iodine test
Deep blue color
Polysaccharide
(starch)
Confirmatory tests
-Benedict’s test
(No red ppt)
-Benedict’s test after
hydrolysis (Red ppt)
No deep blue color
May be mono or disaccharide
Benedict’s test
Red ppt
(Reducing mono or disaccharide)
No red ppt.
(Non-reducing)
sucrose
Confirmatory tests
- Benedict’s test
after hydrolysis
- Seliwanoff’s test
Barfoed’s test
Red scum (Reducing
monosaccharide )
No red scum
Reducing disaccharide
Seliwanoff’s test
Cherry red color (fructose) No cherry red color (glucose)
Osazone test
Osazone test