Question

When you test starch with Barfoed’s reagent, what would be the answer, positive or negative?

Explain your answer by giving reasons and structures.
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Answer 1

My answer is positive.

Answer 2

Barfoed’s reagent

Explanation:

• Barfoed's reagent is used as a chemical reagent to test the presence of monosaccharides.
• It is basically works on principle of the reduction of copper(II) acetate to copper(I) oxide (Cu₂O) that leads to the  formation of a brick-red precipitate.
• In this question it is given that starch is tested with Barfoed’s reagent.
• Starch is a polysaccharide consisting of glucose monomers which are joined together with the help of $\alpha$ 1,4 linkages.
• But as mentioned the Barfoed’s reagent is used to detect monosaccharides.
• Hence, it is concluded that it will give negative result when you test starch with Barfoed’s reagent.