How To Freeze Dry Onions

bunch of different onions with text

Freeze Dried Vegetables

Got a ton of onions but don’t have space to store them? Then how about freeze-drying them so that you have onions throughout the season!

Why Freeze Dry Onions?

Do you ever get this bag of dehydrated onions that look dark and shriveled up? They look totally unlike the onions that you know. But when you freeze dry them, they still have the same color and look the way nature intended them to. Also, as long as you store them right, they can last for 25+ years.

How To Freeze-Dry Onions Using A Freeze Dryer.

  1. Line your trays with parchment paper and place them inside the freezer.
  2. While you’re waiting for the trays to freeze, prepare your onions by slicing or dicing them. You can use a knife, a mandolin, or a slicer, anything that can make your life easier.
  3. Line up your trays with your prepared onions and pre-freeze them. Others go as far as pre-freezing the onions overnight.
  4. After your onions are frozen, place them inside your freeze dryer.
  5. Turn on your freeze dryer and let it do its work. Usually, it takes 34-36 hours.

How To Freeze Dry Without A Freeze Dryer

Freeze drying is still possible with a freeze dryer; however, it does take a load of patience.

freeze dried onions close up

The Freezer Method

  1. Prepare your onions as you would with the freeze dryer method.
  2. Place the onions in freezer-safe or freezer-proof bags or a tray.
  3. Let the aromatics sit in the freezer for 2-3 weeks until completely dry.

The Dry Ice Method

This is the most popular and convenient way of freeze-drying without a freeze-dryer. Faster, too.

  1. Prepare your onions as you would with the freeze dryer method.
  2. Place the onions inside a zip lock bag and lay them on the bottom of a chest cooler.
  3. Cover the bags with dry ice. As a general rule, you’d want to use 1lb of dry ice for 1lbs of food.
  4. Place the lid on top but don’t close or seal tightly. Give some room for air to escape, otherwise, your chest cooler’s going to explode.
  5. Keep the onion bags in the chest cooler for 24 hours.

How Do I Know If My Onions Are Done?

You know the onions are good to go when they are dry, light, crunchy, and flaky. They should easily turn into powder when you pinch them between your fingers.

If you used the freezer-only method, take a piece and let it come to room temperature. If it discolors or turns black, then you still need to keep your batch in for a few days. Yeah, it sucks after waiting that long, but it’s better to extend than to waste a good batch of onions.

How To Store So That They Last For 25-30 Years

Yep, you read it. Freeze-dried onions can last for 25-30 years if stored right. So how do you store them to make them last that long?

You must keep them away from four things: moisture, oxygen, heat, and light.

Store them in a cool dark place that’s free from humidity and moisture. Keep the storage room’s temperature to no higher than 72°F (22°C).

Mylar bags are also perfect for storing them since they don’t take up a lot of space. Especially if you have a vacuum sealer. Get opaque ones and pop in an oxygen absorber or two before sealing.

You can also use mason jars, which will give you two options. One is for short-term storage of 6 months to 1 year. This is great if you’re the type of person who uses freeze-dried onions like crazy. The other is for long term, provided that you put in an oxygen absorber and vacuum-seal it.

onions on wooden chopping block and scooper

Do You Reconstitute Before Using?

Some use the freeze-dried onions as-is or reconstitute them before cooking.

If you prefer to reconstitute, use 3 parts water to 1 part onion. Wait for 20 minutes before you use them.

However, you don’t need to reconstitute if you’re going to use them in soups or stews. Use them as-is since the water from your recipe will rehydrate them. You might need to add more water to get the consistency right.

How To Use Your Freeze-Dried Aromatics

There are many ways to have fun and enjoy your freeze-dried onion.

Using your food processor or blender, you can buzz them into a fine powder. If you prefer a bit of elbow grease, then a mortar and pestle will do just fine.

You can top them on salads for a crunchy, oniony flavor and texture.

Tips and tricks

  • Use the freshest onions you have. Remember that when you freeze dry, you preserve the state that the
  • Pre-freeze the onions in a chest-type freezer. Onions have high moisture content and are sensitive to temperature change. Opening and closing the freezer door will cause ice crystals to form.
  • Put parchment paper on top of the onions when you stack them in the fridge. This will prevent them from sticking to the bottom of the top tray
  • Keep the onion pile no higher than your freeze dryer tray.
  • If you use the freezer-only method, use an empty freezer and keep it undisturbed for 2-3 weeks. Opening and closing the freezer door forms crystals, ruining food consistency.
  • If you need to keep the lid on the chest cooler for the dry-ice method, puncture some holes on top. This way, you keep your food undisturbed while allowing gas from the ice and food to escape.

How did you freeze dry your onions? Did you slice them or dice them? Share your tips and suggestions in our comment section below.

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