What is the colour of fehling solution when fermented with apple juice?

Fehling's solution is a chemical reagent used to test for the presence of reducing sugars. It is made up of two solutions, Fehling's A and Fehling's B. Fehling's A contains copper sulfate, while Fehling's B contains potassium hydroxide and potassium sodium tartrate. When these two solutions are mixed, they form a deep blue solution. If a reducing sugar is added to the Fehling's solution, the copper sulfate will be reduced to copper(I) oxide, which is a red-brown precipitate. This colour change indicates the presence of a reducing sugar.

Apple juice contains several reducing sugars, including glucose, fructose, and sucrose. When apple juice is fermented, the yeast converts these sugars into ethanol and carbon dioxide. However, some of the reducing sugars may remain in the fermented apple juice. If Fehling's solution is added to fermented apple juice, the reducing sugars will react with the copper sulfate to produce a red-brown precipitate.

Therefore, the colour of Fehling's solution when fermented with apple juice will be red-brown.