Stuck!!! Fehling's solution / Reducing sugars

I finally thought i had my head around the idea of reducing sugars until i did an experiment with fehling's solution and maltose...

"why is it that maltose turns the fehling's solution green rather than red??? :redface:

"

sucrose: solution stays blue (not reducing)
glucose:turns solution brick red (reducing)
fructose: turns solution red (reducing)
maltose: solution turns GREEN ??? (reducing?)

Surely because maltose is meant to be a reducing sugar, the Cu (II) ions would turn to Cu (I) in the fehlings soultion, and therefore the maltose would also turn the solution red...

Reply 1

known

I think what you saw was a partial change of colour. If only some of the copper ions are reduced, Fehling's will turn green, then yellow, only going brick red if they are all reduced.

This makes Fehling's a semi-quantitative test, i.e. you can roughly measure the amount of reducing sugar in a solution with Fehling's solution.

Latest

Trending

Articles for you

How to look after yourself and live independently at uni

Try out the app

Continue on web