About 75% of my diet is RAW uncooked food, and I never dehydrate my food over 105 F. Prolonged heating of foods at higher temperatures kill enzymes, and usually dehydrated foods are heated several hours at a time, so if your looking for maximum nutritional value when you eat foods, just don’t over heat. When using the stovetop you shouldn’t heat past 118 F. You want your vegetable to look bright and vibrant not dull, brown/grey and dead. I always keep a food thermometer close by.
Here is an easy article with further references on studies by Ann Wigmore and Dr. Edward Howell.