[Devster]

Hi,
Just wondering if anyone knows the chemistry behind the effects of fructose on the degradation of ascorbic acid over time. We have done an experiment that exemplifies this data, and found many secondary sources that recommend similar results, but no chemistry behind it?

Thanks.

[Dan]

the effects of fructose on the degradation of ascorbic acid over time

Can you share what these "effects" are with us?

It would also be helpful if you can give references for your "secondary sources".

[Devster]

Yeah, was in a rush last time with my post - sorry.

Basically, our experimentation on orange juice strongly indicates that fructose significantly speeds up the degradation of ascorbic acid in the juice. We tested fresh and rehydrated juice over a week, with no added fructose, 5g added and 10g added, and then tested for ascorbic acid every day. The juice without fructose degraded by approximately 4g (due to oxidation, etc.), 5g of fructose degraded by 6g, and the 10g added degraded by about 8g.

Secondary sources such as this one (http://scialert.net/fulltext/?doi=tasr.2009.79.84), support our theory, but the chemistry behind this reaction is not mentioned on any sources throughout the internet. It would be excellent to discuss the chemistry behind this in our report if anyone could help... 

Any help would be much appreciated.
Thanks,
Dev.

[Arkcon]

Question:  Did you try working with a sterile solutions of fructose and ascorbic acid in water?   That would remove all variables except those that you've put in the hypothesis -- that fructose is the reason ascorbic acid is degrading.  Your quoted source discusses many variables, specifically, pH and bacterial contamination, as sort of a survey of all fruit juices.  You may find the reference to the particular reaction  you need, by doing a literature search at the local university.