Cambridge O Level Biology · Syllabus 5090 · Biological Molecules
Benedict's Test
What is Benedict's Test?
A food test in which Benedict's solution is added to a sample and the tube is heated in a hot-water bath, to detect reducing sugars such as glucose and maltose. The blue solution changes through green, yellow and orange to brick-red as the detectable amount of reducing sugar increases under controlled conditions, and a coloured precipitate forms. If no reducing sugar is detected the solution stays blue. The test is qualitative unless the comparison has been controlled and calibrated.
This definition is part of the Biological Molecules chapter in Cambridge O Level Biology.
Questions students ask about Benedict's Test
How do you carry out the Benedict's test, and why must it be heated?
Add Benedict's solution to the sample and heat the tube in a hot-water bath. If glucose or maltose is present the blue solution turns green, yellow, orange or brick-red and a coloured precipitate forms; if no reducing sugar is detected it stays blue. Without heating there is no colour change to observe, so "add Benedict's solution and observe the colour" loses the method mark and produces a false negative. Green, yellow and orange are positive results too, not only brick-red.