Wednesday, July 11, 2012

The Great Blueberry Debate

Onn my Facebook group, Dehydrating Way Beyond Jerky, the question of how to prep blueberries often comes up.  Blueberries have a thick skin. In order for them to dry properly, most books recommend that you pierce the skin in some manner.  That enables the moisture from the inside to evaporate more quickly.

Normally, blueberries are so expensive, I rarely have enough to dehydrate. However, in our last Bountiful Basket order, we ordered a case of blueberries. We got four and a half pounds of blueberries in twelve six-ounce boxes.

I decided to answer this question of how to process blueberries once and for all.

I divided them into three equal groups and decided to try three different methods:

  • Do nothing, just dry them whole.
  • Pierce each one with a toothpick.
  • Use the hot water checking method.

Washand drain

The first two batches were washed and drained. I used my salad spinner to drain them.

Whole blueberries on a screen

Normally, I would recommend using a screen on your rack to allow for greater air flow. But since I didn’t have enough screens, I decided that each batch would get one screen and one fruit leather tray.  Fortunately, each batch only took two racks.

Toothpick Treatment
Using a toothpick, it took me ten minutes to puncture each blueberry.

Checking in Hot Water

Checking is what we call the process of breaking the skins.  I brought a large pot of water to the rolling boil, and then dropped my blueberries in it.  In roughly a minute and a half, the berries began to split.
Cold Water Bath
I removed the berries from the hot water and plunged them into cold water to stop the cooking process.

Although the actual checking time was very short, it took a while to set up the boiling water and the cooling water. 

In the end, the berries were very soft and some even mushy.  I’m thinking if I used this process again, instead of dipping my berries out of the hot water, I would pour them all into a colander to drain before plunging into the cold water.  Blueberries are quite fragile in hot water and quickly cooked beyond what I would have liked.

The End Results?
I saw no significant difference between the toothpicked blueberries and the control group (no puncture or checking)  Except that the do nothing batch took about two days longer to dry.
Control Batch - Do Nothing

Toothpick Batch

The checked berries still dried just fine, but as you can see, the juice ran out and they just weren’t up to what I thought they should be. 
Checked Batch

What to do? Decide for yourself.


  1. Great article. When you say that the control batch took two days longer to dry, what was the total amount of days needed to dry?

    1. Most of the berries were dry in four days. I generally prefer to dry at lower temps in order to assure that we don't get case hardening.

  2. I am wondering what was the temperature you dried the "Boo Berries"


    1. I started out at 115 degrees. but after a day, I turned it up to 120. I prefer drying at lower temps. It may take a bit longer, but I do not want case hardening to happen. Slow and easy does it.

  3. Linda, does taking 4 days to dry something cost a lot in electricity costs?
    I love the way you have set this up and with all the pictures and stuff...I bookmarked this page and as soon as I can get the dehydrator from my parents I will start with probably frozen vegi's or fruit.
    Thanks so much!!

    1. Absolutely not! It only costs pennies to operate your dehydrator.

      Thanks so much, I appreciate the compliment. I guess it's my OCD manifesting myself again...

  4. Here in Vegas they had 11oz containers of blueberries on sale for $1.50. I sooo price matched them at Walmart. Ended up getting 16 - 11oz containers for $24. Which comes out to $2.18 per pound of blueberries. Cha ching! There's one more day of the sale and I might just go get a few more!

    1. Don't you just love it when you begin to find ways to beat the system? I have enough food stores now that there is very little I need to pay retail for. Except for a few items, usually I can hold out until I find a good bargain on something,then I buy as much as I can afford.

  5. what does case hardening mean? the skins?

    1. Case hardening happens when you dry a food item too fast. The surface seales over before the moisture has escaped from the inside. Before long, the food will mold. that's why I keep pushing people to dry fruits and veggies at lower temperatures. However, because of the risk for salmonella, meats must be dried at at least 140 degrees. You can overcome the risk of case hardening with meats by making sure your pieces are very thin, and / or shredding the meat before dehydrating.

  6. I know this is 3 1/2 yrs after your post, but I just found your site and love it! I have heard that meat should be dried at 155 to 160 degrees ... even if it's very thin slices. Now I have a question about the blueberries ... what do I have to do with frozen blackberries? Do I dehydrate them while they're frozen or do I have to thaw them and then follow your instructions with the toothpick? Thanks for your site. Yvette

    1. HI Yvette,

      Sorry I didn't get back sooner, but I don't have internet at home. Have to use wifi...

      Frozen blackberries, like other frozen fruits, can be spread out in the dehydrator frozen.

      You do not need to prick them with a tooth pick like you do with blueberries. Blueberries have a naturally "waxy" surface which prevents inside moisture from escaping.

      You definitely want to dehydrate them at a lower temperature, I recommend 115 to 120 degrees. The reason is the risk of case hardening. This is when the outside dries and seals over before all moisture is removed from the inside. This can cause molding.

      Actually, blackberries are one fruit I have not had much success with. The reason is all the tiny seeds in each little section. The ones I dried were not very tasty.

      However, give it a try if you like and let me know. Good luck and keep me posted!