Benedict's reagent

Benedict's reagent is used as a test for the presence of reducing sugars.

Benedict's reagent can be used to test for the presence of glucose in urine.

Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent.

Benedict's reagent: Excess glucose in urine may indicate diabetes in the patient.

The products of sucrose decomposition are glucose and fructose, both of which can be detected by Benedict's reagent, as described above.

The common disaccharides lactose and maltose are directly detected by Benedict's reagent, because each contains a glucose with a free reducing aldehyde moiety, after isomerization.

Sucrose indirectly produces a positive result with Benedict's reagent if heated with dilute hydrochloric acid prior to the test, although after this treatment it is no longer sucrose.

Specifically, using Benedict's reagent and Fehling's solution the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.

Benedict's reagent goes orange, Tollin's reagent gives a silver mirror, acidified dichromate solution goes green, and Fehling's reagent goes bright red.

To test for the presence of monosaccharides and reducing disaccharide sugars in food, the food sample is dissolved in water, and a small amount of Benedict's reagent is added.

Starches do not react or react very poorly with Benedict's reagent, due to the relatively small number of reducing sugar moieties, which occur only at the ends of carbohydrate chains.