How Does Freeze Dry Machine Work?
Here’s the official definition of freeze drying (Lyophilization) of Freeze Dry Machine
from the FDA:
So, how do we do that at home?
First, you get a heavy duty Freeze Dry Machine (the Harvest Right units drop to -30°F (-34°C) or colder).
Second, you pair this up with a completely airtight chamber that can hold a vacuum (no oxygen) every single time you use it.
Third, you tie in a high end vacuum pump strong enough to suck the stripes off a zebra.
Fourth, you add a heater and thermostat, so you can cycle the temps up and down, repeating the sublimation process for hours on end.
Fifth, tie in a humidity sensor to make sure the water is out, triggering the cycle completion.
What foods can you freeze dry?
Fruits, vegetables, meats, dairy products, meals, desserts, and more. Freeze drying is safe for preserving cooked pasta and grains, unlike canning.
What foods can’t you freeze dry?
Anything that’s mostly fat or mostly sugar will not freeze dry well. Fat won’t dry – but it can heat up and melt in the unit and coat every surface. When I tried pre-cooked pork sausage patties, they made a big mess.
Sugar binds to water, trapping it in the food. This is great for inhibiting bacteria growth, but it means you can’t freeze dry jams and jellies that are mostly sugar. Plain fruit and most desserts are fine.
How long does freeze drying take?
Around 24 hours was the estimated freeze drying time for an average load, but with the new software, I’ve freeze dried loads in as little as 13 hours. Warm, humid conditions increase drying time.
When you load up your home freeze dry machine and hit “Start”, the unit takes you through a short menu. You select whether the food going in is already frozen (or not), and whether it is solid or liquid. Then the Freeze Dry Machine prompts you to close the drain valve and begin the cycle.
Can We mix Foods in Freeze Dry Machine ?
Yes, but watch placement. The website claims that flavors don’t mix, but we have found that they do. We ended up with freeze dried kiwis with a hint of green beans. Advice from the Freeze Dry Machine groups suggests placing stronger flavored items on the upper shelves, milder items on the lower shelves.
As always, proper food safety rules should be observed. Avoid cross contamination, dry thoroughly, and package promptly.
How do I know the food is done freeze drying?
The freeze dryer senses the moisture content of the food and finishes the cycle automatically, but sometimes it’s a little off and you need to add extra time.
When you first remove food from the Freeze Dry Machine, it will be a little cool from the ice buildup inside the chamber, but not “cold”. I always break open some larger pieces and check inside for cold spots. If you find cold spots, put the trays back in and add time to the drying cycle. Your freeze dryer will prompt you to check for dryness.
How do I store the freeze dried food?
THIS IS VERY IMPORTANT! Once the freeze dry cycle is complete, you must package the food in containers that moisture and oxygen proof, such as Mylar, mason jars or cans. Adding an oxygen absorber helps to ensure freshness.
Meat with any amount of fat will go rancid in a matter of weeks if not properly sealed in an airtight container with oxygen absorber. Putting it in a mason jar and screwing on the lid won’t cut it.
We use Mylar bags for most of our long term storage because they are light and durable. You can reuse Mylar, but of course the bag will be slightly smaller. Mylar is great for camping and travel.
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