It is the height of blueberry harvest in South Jersey and I'm getting ready to dehydrate a batch. After many years, I think I've come up with a pretty efficient process that preserves the nutrients.
Most sources will tell you that you need to checker the waxy coating on blueberries in order for them to dry properly. One look at the water left over from the process and you'll see a lot of phytonutrients you won't get to enjoy. You will also have a blob of mushy berries.
Here is my process:
Get a friend to chat with or put on a podcast, video or audiobook you enjoy. Nothing that requires note taking. :o) Conscripting one's children is a good option, too.
Put a large bowl or roaster pan at your feet to catch your blueberries.
Thread a clean needle with button thread (a tapestry needle works well) and start impaling blueberries. Don't go through the "poles" of the berries, but make sure that you pierce the skin twice with your needle. Let the end of the thread dangle into the bowl; if some berries slip off, don't worry about it. After you have quite a few berries on your thread, slide them off the thread and into the bowl. Keep going until you run out of berries or dehydrator space.
Pour berries onto a dehydrator tray. They will roll around like ball bearings and can be coaxed into a single layer pretty quickly. Dehydrate as usual. There are always a few stubborn individuals that won't have dried. You can either take them as your treat or poke them again and give them another trip through the dehydrator.
By the way, this doesn't work with cranberries. Those need to be sliced in half on the equator.