Drying Apples - Methods to Preserve Vitamins?

I slice and dry crabapples, and am curious to know their vitamin content. This is both as a frugality option (preserving free fruit!) and as a potential technique for some hypothetical longer-term survival/disruption situation. We have long winters; vitamins matter.

As usual the Web was no help -- lots of contradicting opinions based on nothing concrete, all the while trying to harvest my email address.

So -- I have two questions for the Permies hive mind:

1. Does some Vitamin C survive the process of dehydrating apples?

2. Are there methods of dehydration more likely to preserve vitamins?

Drying at cooler temperatures will help preserve nutrients. Between 80-100F is a good range. Specifically for Vitamin C, it starts to degrade at 95F and degrades faster the higher the temperature. Most dehydrators that I have seen dry things between 120-160F... which degrades the product much faster than at a cooler temp. But you also have to dry it for longer. 5 days instead of 5 hours.  A by product of drying at a cooler temperature is that you are typically pulling moisture from the air and letting the moisture leave the product naturally. This is different than most dehydrators that seem to force the moisture out with heat. I don't have any science to back it up, but I suspect this also helps.

Drying them as quickly after being harvested as possible will also help preserve nutrients. Time sitting will degrade nutrients, until they are dried.

And lastly, keeping them out of sunlight will help preserve nutrients for longer.

Freeze drying is probably the most effective method for keeping nutrients, but drying cooler and slower is way up there.

Please don't take any of this as a knock against dehydrators. I would much rather people dehydrate their own food, which will have far more nutrients, even if it is dried the "normal" way, than to buy things from the grocery store that have been shipping half way around the world.

Matt McSpadden wrote:Drying at cooler temperatures will help preserve nutrients. Between 80-100F is a good range. Specifically for Vitamin C, it starts to degrade at 95F and degrades faster the higher the temperature.  

Yes, that makes sense. Thanks!

I will continue to dry the over-ripe  "horse treat" apples in the open air and sun.

But for the nicer apples intended for human consumption, I will dry them indoors in a cabin I have on my property. It gets nice and warm but not too hot. I can lay out the apple slices on racks and run a fan on them.