Summer is slowly approaching and we can pull something a little more exotic from our archive of freeze drying tests. In one of the tests we loaded the AMARU freeze dryer with dragon fruit, which most of us will probably know primarily as a flavour for various lemonades or juices.
Preparation
Personally, I am one of those who is more impressed by the appearance of this fruit than the taste. It's not that dragon fruit isn't good, but it doesn't quite fall into the category of something I regularly need to have in my menu.
Therefore, preparation was a bit of a struggle for me to peel the product well. I managed to do that in the end, and I loaded two different varieties onto five produce shelves. Some just sliced into large rounds, others diced.
Freezing
Since I got about 8 kg of product at room temperature into the AMARU freeze-dryer, I set the freezing phase to 15 hours preferably. This was sufficient time in the end, as the temperature of the product reached the required -25°C before the drying process started.
Drying
From a glance, it is clear that pitahaya has a lot of water in it, estimated to be similar to kiwi. On the other hand, once cut, there is nothing to prevent the water from sublimating, and the straight cuts also allow the product to sit well on the product tray, allowing for efficient temperature transfer.
I finished the drying process after about 33 hours, but by that time the pressure in the chamber had reached about 120 mTorr. If I tried the same loading next time, I would set the time 3 hours shorter.
Result
As the pressure suggested, everything was dried without residue. See for yourself in the video:
Usage
As with all fruits, pitahaya can be easily rehydrated by adding water. Personally, though, I could see the point in freeze-drying dragon fruit right at the source, i.e. somewhere on the farm, to preserve its freshness and extend its shelf life.