Freeze drying food in an ordinary chest/deep freezer.

Jones

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Freeze drying food was mentioned in the canning thread and the cost of dedicated appliances to do it was mentioned. They are pretty expensive. However, I found some articles that suggest that food can be freeze dried in an ordinary freezer only the process takes longer. Where a freeze dryer can complete the process in up to 48hrs, it takes 3 - 4 weeks in an ordinary freezer.

A chest freezer is also a lot less expensive than a freeze dryer.

How to Freeze Dry Food in a Freezer

A home freezer makes it easier for people who want to freeze-dry food for the first time. If you have a deep freezer, it even makes a better option to use. But your typical home freezer will still work.

  • Place the food on a tray or plate after spreading the food out
  • Place the tray in the freezer — the food needs to be frozen at the lowest temperature
  • Allow the food to stay in the freezer until it’s completely freeze-dried – 2 to 3 weeks
  • Once the process is complete, pack it in an air-tight storage bag and store it in your freezer or pantry.
Link.

Quick Step-by-Step to Freeze-Drying with a Freezer:​

  1. Place Your Food On a Tray
  2. Put The Tray In Your Freezer
  3. Wait 2-3 Weeks
  4. Store Your Food in Air-Free Bag
One misconception is that the freeze drying is a massively complex procedure, when in reality, you can do it in your home freezer.

The only thing you need is a normal cookie sheet or cooling rack.

All you need to do is place your food in small pieces and place them in your freezer.

A deep freezer works best but your normal freezer will work.

The food starts to freeze in the first few hours itself, but it's important to note that the drying process will take weeks before you'll have the freeze dried food you want.

This process is known as sublimation and is what separates freeze drying from simply freezing food inside of sealed bags or containers like we’re all used to doing.

The best way to check when the food is done drying is to remove a frozen piece and let it come to room temp.

If the food turns dark or black, it means the drying process is still not over.

Frozen food that doesn’t change color has been freeze dried thoroughly.

Knowing if you've made freeze dried food is definitely more of an art than a science and will take a trail and error process to get it right.

It is important to note that starting out with simple foods that have a high water content is the best place to start.

Try things fruits like apples, berries, and bananas. Or try vegetables like broccoli and peppers. These are the easiest to do and practice on.

Once that has been achieved, you can go ahead and store the freeze dried food in ziplock bags.

Freeze-dried food should be kept in storage that stays under 75 degrees.

Link.

Food Types Suitable For Freeze Drying​

  • Coffee
  • Fruit and juice
  • Vegetables
  • Meat
  • Fish and Seafood
  • Eggs
  • Dairy
Some foods freeze dry very well, but not all food is suitable for freeze drying. Small fruits and vegetables can be easily freeze dried, whereas whole fruits and large vegetables would not be suitable, although they can be freeze dried if cut into small pieces first. This also applies to meat; small chunks of meat freeze dries well, but larger fillets need to be cut into pieces. Meat and seafood also require cooking before freeze drying. For some foods freeze drying is not cost-effective.
Link.

Another way that was mentioned for testing food to see if the drying process is complete is to snap the food in half and feel with finger or tongue if a cold spot can be detected at the centre. Cold spots are where moisture is still retained. One lady mentioned using a thermal imaging camera to detect cold spots on the food.

The food can then be vacuum sealed in mylar bags with moisture absorbing sachets for added protection against spoiling, though many seem to use ordinary jars or ziplock bags with or without the sachets from what I've read.
 
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