Why red precipitates were formed when fehlings a and b were added to solutions like starch or diastase.

Question

i need some answers, it's a very complicated question. only a true genius can answer this nosebleeding question

Answer 1

aliphatic aldehydes are present in the solution that result in the formation of Cu2O.

Answer 2

The starch solution was probably not fresh and contained some reducing sugars from its breakdown which reacted with the Cu++ in the Fehling's to produce red copper oxide Cu2O.

The diastase solution was contaminated with some reducing sugars giving a positive reaction with then Fehling's