Best practices for dehydrating (drying) blueberries

In the past two weeks I have processed 51 pounds (not including the spoils of picking fresh) of blueberries, from 3 batches. The first two batches were from the Henna Blueberry Farm in Fall City, Washington. We picked there on July 23rd and July 30th. The blueberries from the u-pick farm were very early, and mid-season (yes, it’s a very late season this year)! The last batch was big ripe peak season berries from a commercial grower in Oregon, purchased Aug 1st at my local Fred Meyer.

My intent was to consume fresh about half the berries and put the rest away for winter. For fresh consumption, I’ve made a blueberry streusel pie, a blueberry crisp, a summer (mixed) berry crisp, oatmeal crisps with fresh blueberries, and a plain blueberry pie. The streusel pie was a knockout hit.

For preservation, I made 3 quarts of blueberry jam, 6 quarts of blueberry pie filling, and just over 2 quarts of dehydrated blueberries. Making jam (hint: Pomonos pectin) and pie filling (hint: clear-jel) are straight forward, but finding good advice for dehydrating blueberries left a lot of room for interpretation and experimentation.

My research on dehydrating blueberries boiled down to 3 discrete steps:
a) wash the berries
b) break the waxy skin of the berries (slice, puncture, or blanch)
c) dehydrate at 135°

I have found that temperature isn’t terribly important. I made a batch of yogurt and dehydrated some berries at 115° to no ill effect. I’ve gone up to 145° but didn’t like the texture as much. If just drying berries, I use 135°, as my dehydrator manual suggests. I vary the temperature for my convenience, like having a batch finish at 9AM instead of 6AM.

To puncture the skin, I didn’t much like the idea of slicing every blueberry in half, or of poking a hole in every berry so I tried blanching. I varied the blanching time between 30 seconds and two minutes. The results are dehydrated berries, but a less than satisfactory experience.

The blanched berries dry very unevenly. I pulled some off the dehydrator at 12 hours, some at 18, and others after 24 hours. The skin of the blanched berries tends to get dry and crispy before the center gets leathery. So part of the berry is too dry by the time the center gets dry enough. The berries that dried the best were blanched longer, and they also tended to mush and leak juice all over the trays, making for more cleanup. I doubt I will ever blanch and dehydrate blueberries again.

Last night I dried a big batch bananas, as well as a few more trays of blueberries. For comparison, I sliced a batch of blueberries in half, I poked a few with a sharp knife blade, I poked others with a paper clip, still others with a hole poked through both sides of the berry with the paper clip, and finally, a set of berries on the paper clip, shish kebab style.

After dehydrating overnight, the bananas are all dehydrated to perfection. The sliced in half blueberries were also dried to leathery perfection. Not a single sliced or poked berry was even close to leathery, and all were still quite moist. The least dehydrated was the shish kebab berries, since the paper clip plugged the holes.

I would like to find a solution that dehydrates the whole berry while producing sliced-in-half texture and flavor. Until then, slicing in half requires a bit more prep, less mess and cleanup, consistently better results in a lot less dehydration time, and no sorting needed while packaging them.

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