Strobist Info YN-560, Author: Andrés Nieto Porras, Licence CC-SA 2.0
There are a number of methods of preserving eggs for longer periods of time, usually different types of brines. However, generally you cannot count on a shelf life of more than a few months, maybe one or two years. In contrast, freeze-dried (and well stored) eggs can last over 10 years in an edible state.
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 purposes of our AMARU test, I chose eggs as a liquid mixture of egg white and yolk in a bottle. If I wanted to sell the eggs, I would focus on careful selection of the supplier and put a lot of effort into maintaining freshness. However, for the trial itself, I primarily wanted to avoid "cranking out" several large platters of eggs.
The mixture used did not even need to be stirred and it was enough to pour a total of 5 litres from individual bottles onto the product trays. Of course, it would be possible to pour more than 1 litre on each tray, but then a longer drying process has to be taken into account.
When using fresh eggs, I would of course recommend scrambling the yolks.
Freezing
The egg mixture has no problem freezing and I left the five litres frozen for 11 hours. Our probes subsequently revealed that a time of around 9 hours, when the product was below -30°C, would have been sufficient.
Drying
I set the drying time to 32 hours so as not to underestimate anything. After 27 hours, I interrupted the process to check the status and was again pleasantly surprised to find the eggs sufficiently dry.
So the process was terminated and the trays removed. We design the apparatus so that at no stage does the temperature of the product exceed approximately +35°C, even in the later stages of drying. Nevertheless, a temperature of around 30°C during removal was sufficient to produce the specific smell of raw eggs and it is good to take this into account.
Result
The structure of the freeze-dried eggs is similar to, for example, yoghurt or milk. The coherent layer cracks during the process and a wrinkled texture forms on the surface. They can easily be scraped off the stainless steel tray and I found it useful to grind them a little more to a finer powder before packing. They don't take up as much space in the containers then.
Rehydration
I would not recommend eating freeze-dried eggs just like that. The drying process does not work like sterilisation and the eggs, although dry to powder, are still raw. After rehydration, they need to be cooked.
I have tried bringing the mixture back to a usable state with warm water. It takes a little patience, as clumps form at first, but even these dissolve after a few minutes. Slightly warmed milk works just as well.
Uses
It's clear that eggs in the form of freeze-dried powder will never make Easter eggs. Nevertheless, the field of application remains wide. I myself have tried to prepare them in my favourite form - scrambled. I guess I didn't add enough water, so the mixture was thicker, and this was reflected in the fact that on a hot pan (with bacon, of course!) the eggs were ready in no time.
I was a little worried about the added water splashing on the pan, but nothing like that happened. My other surprise was the taste. It was quite distinctive in a positive way. The texture was a little different. The eggs in the pan formed what I would describe as "carpet-like formations" - even with constant stirring, they came together and needed to be stirred. I attribute this effect more to the lack of water, which I should have used more of.
Lyophilized eggs could be appreciated by many people. From preppers to regular housewives. While some may have a block with the fact that it is a powder, I personally appreciate it for those moments when the egg tray in the fridge is yawning empty. I usually find out the moment the hunger demon possesses me.
