|MadSci Network: Biochemistry|
Fructose and glucose are freely interconvertible at alkaline conditions due to keto-enol tautomerism. If you take pure glucose OR pure fructose and expose them to alkali, the glucose and fructose establish an equilibrium, i.e. after a while the concentrations of both substances reach a point where they remain stable (unless external conditions change). Acidifying the solution will not cause any further change in the ratio of fructose to glucose.
http://www.uni- regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/D- Fehling-e.htm
Artem G. Evdokimov
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