Cucumber season is in full swing and why not take advantage of this by testing our freeze dryer? This time, rather than the final product, we wanted to show how AMARU can handle extremely watery foods and what drying them in a freeze dryer entails.
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
For the test, I purchased a total of 6.6 kg of slicing cucumbers. After peeling and slicing into rounds, the loading came out to exactly 5 kg, i.e. 1 kg for each produce tray. It should be mentioned that I didn't worry too much about the width of the slices. Sometimes it was around 1 cm, other times barely a few millimetres. The process will show which is better.
Freezing
The cucumbers were of course loaded at room temperature, around 22°C. So far, the cucumber is probably the record holder in our tests in terms of water content. It took AMARU 12.5 hours to freeze them.
Drying
Although even a smaller pack contains quite a lot of water, this can sublimate very well from the product. The cucumbers are sliced, and the side walls of each slice are free of any skin that could in any way prevent the evaporation of water. In total, we let the cucumbers dry in the AMAR for 35 hours, but according to the data, nothing changed (the cucumbers were dry) after about 28 hours of drying.
Result
Some things can be freeze-dried and some things cannot be freeze-dried. Some things make sense to freeze-dry and some things do not. The slicing cucumbers are a combination of 1 - 2, so it is possible to freeze-dry them, but it probably doesn't make much sense. As I said at the beginning, this was mainly a demonstration of drying extremely watery foods.
For the sake of interest, only about 40 g of each 1000 g of cucumber remained before drying. This means that the cucumber contains about 96% water.If you take 96% out of anything, there's not much left, and that's the case with cucumbers.Visible "shrinkage" is then a manifestation when a mere 4% of the remaining material is not enough to maintain the original shape.
RehydrationThe first test showed that the snakehead cucumber can return to its original, actually fresh, form.After a while in water, the slice becomes a juicy piece of cucumber again.
Uses
The stumbling block in the business plan is the almost zero yield. If you freeze-dry 10 kg of cucumbers, you will end up with only 400 g of freeze-dried product. Thanks to the possibility of rehydration, this is not complete nonsense. After all, a freeze-dried cucumber in water will flavour the cucumber much more than a fresh cucumber, and I want to test how the salad will taste when the dried cucumbers take back moisture directly from the dressing.
However, from a business point of view, it is hard to imagine the price for each 100g of such freeze-dried cucumber. Similarly, freeze-dried asparagus, for example, performs in the same way but cannot be brought back to its original state by adding water.