Define Observation for Benedict Test - Carbohydrates?
An insoluble reddish brown precipitate of cuprous oxide will be obtained. This is similar to Fehling's test.
The reddish brown precipitate indicates the presence of a reducing sugar. All monosaccharides are reducing sugars and thus will give a positive Benedict's test.
Maltose and lactose have a free aldehyde (sugar) group and are thus able to reduce Benedict's reagent. Sucrose, however cannot reduce the cupric ions in Benedict's reagent since the sugar groups are tied up in a glycosidic linkage.
Just as in Fehling's test, starch cannot reduce Benedict's reagent. Dextrin being a less complex molecule has more free sugar groups and partially reduces Benedict's reagent.