Freeze Drying Watermelon sticks

Make even slices

Make sure to cut the slices as equal as possible. The freeze dryer cycle will take as long as the thickest part of the food. With watermelon, it wasn’t as important (because watermelon has a simple structure), but the freeze-drying process of other foods can be complicated by drying variable food thicknesses.

We decided to make sticks with our first watermelon test. We tried to cut them the same thickness as the original slices.

Ready to load the freeze dryer

As with any snacks that we want to easily store in a jar, it’s easiest to keep them separated before the food is freeze dried. I decided to use the silicone mats we made…just in case things get too sticky. This ended up being a light load because we didn’t pre freeze the watermelon, and pile it on the tray.

Removing the finished watermelon from the freeze dryer

In the video, you’ll see exactly what the watermelon sticks looked (and sounded like) as I removed them. They were popping as they adjusted to normal atmospheric pressure. Everything was perfectly dry. After doing an analysis on the freeze drying cycle, my guess is that this could have had a much shorter dry cycle. That being said, I likely should have either prefrozen them, or increased the time of the freeze cycle.

As you can see from this video, I don’t think I needed the silicone mats, but I used them anyways.

Watermelon residue

Here’s part of why I say that I didn’t need to use the silicone mats. The watermelon sticks really didn’t stick very much. Had I not used the mats, I likely would have had a bunch of broken sticks…not too bad. But the cleanup is always super easy with the mats, so why not?

The spoils

I get to enjoy the small pieces :).

What did I learn?

  • Less-than-flavorful watermelon becomes quite tasty when freeze dried…I can’t wait to try some super sweet watermelon
  • Freeze-dried watermelon makes cool popping sounds as it’s removed from a vacuum (it reminds me of rice crispy cereal in milk)
  • It’s difficult to load a jar with freeze dried watermelon sticks when you’re holding a phone/camera

Things to try next time:

  • Could I use a shorter final dry cycle?
  • Should I prefreeze the watermelon?
  • Chunks vs sticks
  • Next time I want to try riper/better watermelon

2 thoughts on “Freeze Drying Watermelon sticks

  1. Please explain your comment about a longer freeze cycle and what that would change .


    1. If you’re referring to the video where I explain that the watermelon sticks appeared a bit shriveled…and that “maybe I didn’t freeze them long enough”, I have found that high-sugar food items need much more freeze time to keep their cell structure as intact as possible. High-sugar and high-salt food items have a much lower freezing point, which means that they will need more time in the very low-temperature freezing environment to completely freeze throughout.

      My guess is that the watermelon sticks shrunk quite a bit because they needed more time to freeze. I typically pre-freeze anything with high sugar or high salt, and then I set an extended (typically 12 hours) freeze cycle.


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