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nafex - Re: [NAFEX] Vitamin C in Jelly?

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  • From: Richard Moyer <ramoyer@gmail.com>
  • To: nafex@lists.ibiblio.org
  • Subject: Re: [NAFEX] Vitamin C in Jelly?
  • Date: Wed, 22 Apr 2009 22:53:32 -0400

Jim,
Some thoughts on Vit C loss in processing fruits:
One of the Biochem labs I've done with my students over the years involves extracting and titrating to determine the amount of Vit C of raw juice vs. fruit juice boiled for 5 minutes. Vit C levels is an easily performed test that you might find a lab to do for you.
If I remember correctly, the most Vit C we lost in 5 minutes of boiling was around 50%, or a reduction of 1/2.  The greatest loss was for foods with lower levels of Vit C to begin with.
In order to correct for other interfering compounds we would also treat a parallel sample with ascorbase, to destroy all detectable Vit C. 
 
Scandinavian researchers have noted for years that berry (small fruit) jams and jellies are a rich source of Vit C, other antioxidants and phytochemicals.  Vigorous brief boiling preserves more nutrients than longer boils.  Low sugar 'jams' also deliver more Vit C than those with so much sugar, as one can eat so much more without being sated (or feeling guilty).
 
Don't know the degrees but I suspect that low sugar 'jams' or 'jellies' also boil at signficantly lower temps, which also could preserve more Vit C.
 
Commercially prepared and processed jellies may indeed have lost most of their Vit C; I don't know the length and temps of the steps involved.
 
One could add purified Vit C back in near the end of the process, but that raises other issues.
 
Richard Moyer
Castlewood, VA



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