Which of the following are reducing sugars
a. Monosaccharides: - Pentoses (Ribose and deoxyribose) and Hexoses (glucose, fructose, galactose)
All members of this groups have reducing property
b. Disaccharides: - Lactose and Maltose are reducing sugars and forms their characteristic osazone crystals (Lactosazone crystals-cotton ball shape [ Power puff] and Maltosazone crystals “sunflower shape”), whereas sucrose is non-reducing and does not form osazone crystals
c. Selivanoff’s test → Fructose and sucrose are the only two, which give red colour with Selivanoff’ s reagent
d. Molisch’s test → +ve given by all carbohydrates.
Note →this test is also given by Aldehydes, formic, oxalic, lactic and citric acids
e. Reducing property is due to free — Aldehyde or ketonic group (absent in sucrose, that is why it is non reducing)
f. Benedict’s test → for Reducing sugars
g. Cole test → for Reducing sugars
h. Barfoed’s test → + ye test given by only monosaccharides (Reducing)
i. Bial’s test for Pentose
j. Trehalose → is a disaccharides →major sugar of insect hemolymph.