How does Benedict's solution detect sugars?

Benedict's solution, or reagent, works by oxidizing the sugars to form carboxylic acid and a red-tinted copper oxide. This only works because of the reagent's mix of copper sulfate, sodium citrate and sodium carbonate. The substances are boiled in water.

The test only reacts with reducing sugars such as fructose and glucose, but is unable to react with sucrose found in table sugar. It is used in the food industry to test for sugars as well as test for glucose in the urine of suspected diabetes suffers. The solution is blue at first, which indicates no sugars. Once it reacts with a reducing sugar, the color will change to green, yellow, orange, red or brown, with brown indicating a high level of sugars.