We freeze-dried bananas more than a year ago. At that time, however, it was a small set-up, when it was necessary to verify the basic functionality of the prototype. This time we took on a regular test to show you how AMARU handles the freeze-drying of this fruit.
Note: This test was performed on an earlier model of the AMARU lyophilizer. We have made several improvements since then and today the capacity would be higher and the process faster.
Preparation
It is clear that the bananas need to be sliced, but the question is to what thickness. As you can see in the quick video below, I started with pieces up to over 1 cm thick. Then I realized that even 8.5 kg of purchased bananas would not be enough, so I started cutting rounds about 0.5 cm thick. In the end I still had one bunch of bananas left.
All in all, we put 4.3 kg of material into AMAR, and obviously more would have fit if all the slices were around 1 cm thick. Although banana preparation is one of the fastest, in an industrial deployment I would recommend using a spray bottle with lemon water or slicing and stacking on product trays with more than one person.
Freezing
We loaded the bananas at room temperature, but because there were not so many of them, the desired temperature for freeze-drying was reached after 9.5 hours.
Drying
Lyophilisation of the whole load took about 29 hours.
Result
Traditionally, you can see for yourself in the video below. The bananas are light, crispy and even the thickest rounds had no hints of moisture in the middle. After drying, we weighed the entire load and the result is 1.1 kg after drying, a ratio of about 25% of the original 4.3 kg.
Rehydration
The banana is a versatile food that can be eaten straight up dry or just moistened for a fresh banana anytime. A little more time is needed for rehydration as it takes a while for bananas to properly reabsorb water.
Uses
The uses of freeze-dried bananas would probably take an article in itself. Thanks to their concentrated flavour, they can be used in the confectionery industry, even in the form of banana powder, which can be made from freeze-dried bananas in a regular kitchen blender.