Carbohydrate Test108
Molisch test
Molisch reagent consisting of ÿ-naphthol in alcohol will react with furfural to form a purple
complex compound which is caused by the dehydrating power of concentrated sulfuric acid
towards carbohydrates. A negative reaction result indicates that the solution being examined
does not contain carbohydrates. Meanwhile, the formation of a purple ring indicates a positive
reaction.
Benedict's Test
Alkaline copper solutions will be reduced by sugars that have free aldehyde or ketone groups to
form colored cuprooxide. Reducing sugars react with reagents to produce a brick red precipitate
(Cu2O). In reducing sugars there are aldehyde groups and OH lactol. The OH of lactol is the OH
attached to the first C atom which determines whether the carbohydrate is a reducing sugar or
not.
Barfoed Test
This test is to differentiate monosaccharides and disaccharides. In this experiment, carbohydrates
were reduced in an acidic environment. Disaccharides will also give positive results if boiled
long enough for hydrolysis to occur.
Seliwanoff test
This reaction is specific for ketose. The basis is the change in fructose by hot acid into levulinate
and hydroxymethylfurfural which then condense with resorcinol to form a red compound.
Tollens test
This test is positive for pentose carbohydrates which differentiates them from hexoses.
Sucrose Hydrolysis
Sucrose is a disaccharide carbohydrate. Sucrose hydrolysis is to prove whether the hydrolysis
results of sucrose are glucose and fructose, that is, after the sucrose is hydrolyzed, the hydrolyzed
solution is tested using the Benedict test to prove glucose and the Seliwanoff test to prove there
is fructose.
Glycolysis experiments in yeast
In humans and animals, the final product of anaerobic glycolysis is lactic acid, while in yeast
anaerobic glycolysis (sugar fermentation) produces ethanol. In this experiment we will see the
results of anaerobic glycolysis in yeast in the form of CO2 and ethanol. Apart from that, we will
also look at the effect of inhibitors on anaerobic glycolysis.