Summer is slowly over, but it wouldn't be our little AMARU if he couldn't save a bit of it for us, even on frosty winter evenings. Luckily, we have an Angelato shop not far from our workshop, which is handmade and probably the best ice cream in the country, offering unusual flavours too.
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
Here it will probably take a little longer than usual. Preparing ice cream for the freeze dryer is probably one of the hardest I've experienced so far. It takes time to pour or stack something onto the product trays, but ice cream is also about tactics, plan and patience.
Judging by the look on the faces of the ladies at Angelato pastry shop on Bělohorská Street, I was probably the first person in a long time to ask for five litre tubs of gelato (milk) ice cream. I preferred to skip the sorbets (water), because I can't say what would be left of them. In the end, I took one flavour for each tray
Poppy seed and plum
Lavender
Blueberry Cheesecake
Pistachio
Yogurt
Ice cream can't simply be cut into trays. These should definitely be pre-frozen in an AMARU or freezer. I myself waited 2 hours when the trays reached a temperature of around -10°C. The tricky part, however, is hitting the right ice cream temperature for processing. If you leave the ice cream tray in the AMARU too long, it becomes a brick that can't be cut even with a sharp knife. On the other hand, it can't just be just below freezing, because it will then continue to heat up and melt during processing.
I originally intended to use a scoop of ground coffee for dosing. However, that didn't work at all. Since the ice cream was still soft, I decided to use a candy decorating machine, which had already found its use in freeze-drying cottage cheese desserts. However, a new question arose, namely which attachment to use. Dispensing directly onto the tray of cute "flowers" quickly took its toll. The ice cream does not stick to the frozen tray and rather slides on it. As a plan B, I should have made a long noodle across the length of the entire stainless steel tray. That was better, but before I could fill the entire tray, the first applied strips started to melt. Plus, with both attachments, I wasn't able to use up the entire one pound tub of ice cream.
In the end, the attachment that formed a strip about 5 cm wide and about 1 cm thick turned out to be the best. This way you can put the whole tub on one tray and still have room left over. In addition, thanks to the thickness, the problem of spreading has disappeared.
Note 1: I haven't mentioned it yet, but you have to take into account that the ice cream will be almost everywhere. That is, at least if you have a low-quality decorating machine that leaks everywhere.
Note 2: Angelato has one " disadvantage" - they use ingredients, not flavorings. Thus, instead of blueberry flavoring, you'll find whole blueberries in the ice cream. This is great for eating, but not so much for the nozzle of the decorating tool :)
Freezing
As much as you get annoyed with the preparation and sticky everything, I have better news in the freezing area. Because the ice cream doesn't have to go through a phase where the water freezes, so it takes no more than 5 hours to reach the required -30°C in AMARU.
But of course, you have to take into account that AMARU freezes the previously mentioned 2 hours in advance and, moreover, during the entire time the product is being loaded. As a result, the ice cream was already -6°C when it was loaded.
Drying
A total of 5 kg of different ice creams were dried for 28 hours. This is much less than the time it normally takes for cabbage or fruit. The faster process is due to the absence of any skin to prevent water drainage.
Result
Simply fabulous. I'm not even going to go into too much detail because the annotated video below captures it well.
Rehydration
Classical rehydration would be pointless in the case of ice cream, although there is nothing to prevent dissolving the ice cream in water (milk) and refreezing the resulting mixture.
Uses
Your customers will no longer have to undergo the harsh and selective process of NASA's astronaut selection process, where they won't get any freeze-dried ice cream after all. A point to address, should the concept appeal to you, would be the process of loading the ice cream onto product trays to create a nice and easy to package product.
It's also worth considering crushing the ice cream into a powder that can then be used in shake cocktails with simple and elegant preparation, but still made from honest ice cream.