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How to Dehydrate Onions for Long-Term Storage

Learn to dehydrate onions in a safe way that helps you create awesome minced onions for cooking, and allows you to make your own DIY onion powder that is so much better than storebought!

Dehydrated Onions in a clamp glass jar with onion powder in a measuring spoon
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So before we get started, the first question is always this:

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Do Onions Smell Up the House?

Yes, yes they do. So you may want to find a way to dehydrate your onions in the garage or outside if the weather is nice. No high humidity and temps above 70°F for the best efficiency.

Prep table of chopped onions and onion skins to dehydrate onions.

In our family, I’m even required to process the onions outside if I’m doing a dehydrator full. Then my machine sits on the back porch until dusk until I bring it in to finish overnight and into the next morning. The smell is less obvious by then for our family.

TIP FOR SMELL: You can blanch your onions before dehydrating them. Not only does it help cut down on the oils that smell, it helps drying time go a little faster, as well. You can cut, then blanch for 30 seconds or so, dip into an ice bath and dry, or you can caramelize onions for a richer, deeper flavor, too.

How to Dehydrate Onions

Quick Instructions: Chop or slice onions, dry at 125°F/52° for 10-18 hours.

Nesco dehydrator FD-75 with tray of chopped onions to dehydrate onions with gloved hands.

Equipment Needed:

  • Knife or vegetable chopper or food processor
  • Cutting board
  • Dehydrator mesh or parchment paper
  • Dehydrator

Instructions:

  1. Wash onions.
  2. Cut off the root end and peel away the skins (but save them to make onion broth* or vegetable broth later!)
  3. Cut into slices or pieces of your choice. I use a Fullstar Vegetable Chopper for doing in bulk, but a knife is all you need.
  4. Place on dehydrator trays – separating the layers for better drying efficiency.
  5. Dry at 125°F / 52°C for 10-18 hrs. * (
  6. Condition.
  7. Store in airtight containers.

* Drying times are variable. Depending on the size of the onion (more moisture and sugar), your home’s humidity, the power of your machine, you could dry in as little as 10-12 hours, or from 15-18 hrs. I tend to push the longer end for drying my onions because I want them as dry as possible.

Geta dehydrating magnet for your machine and you’ll never have to wonder about temperatures again!

* ONION BROTH: I throw it in with some more onions and onion skins, and lots of water, and let it go overnight to create a dark, rich, onion broth. Use to cook grains with, to put into other soups, to use as a means of liquid when water is called for in cooking. It’s good stuff!

Nesco dehydrator tray with finished dried onions.

When are Dehydrated Onions Done?

Check by cooling a few samples of your onions to room temperature. They should be a little pliable, but dry.

If you blanched first, your onions should snap apart when dry.

Oven Directions:

  1. Wash and chop onions as above.
  2. Spread onions onto a parchment paper-lined baking sheet. I prefer to put the parchment paper on top of a cooking rack that goes on top of the baking sheet to help stop hot spots.
  3. Place into an oven preheated to it’s lowest temperature (below 200F is preferred. The lower the better).
  4. Crack the door with a wooden spoon or silicone spatula to help the moisture escape and reduce the temperature.
  5. Dry for 3-6 hours until onions are completely and snap once samples are cooled.
  6. Condition.
  7. Store.

Do I Need to Condition Dried Onions?

Yes, as with all dehydrated foods, conditioning is a vital step in the storage process.

  1. Place dried food into a jar to allow movement. Do not add moisture absorbers or any other desiccant.
  2. Shake once a day for 5-7 days.
    • Look for signs of sticking, clumping, or moisture buildup.
      • If you have clumping or sticking to the side of a jar, if it is removed with a gentle shake, it is fine.
      • If it takes significant shaking to remove it or break it up, place back into the dehydrator to dry more.
    • If you see mold of any kind, throw food away and sanitize the jar.
  3. Once complete, store in an airtight container in a dark, cool, dry place if possible.

Learn more: Using Dried Onions in creating Mirepoix and The Holy Trinity

How to Store Dried Onions

Store in an airtight container.

Dried onions will generally last two years, but you will likely get much longer storage.

Kitchen Aid coffee Grinder with minced onions to powder for DIY onion powder

DIY Onion Powder

Creating your own onion powder is as easy as 1. 2. 3.

  1. Put your fully dried and conditioned minced onion pieces into a grinder of your choice (a coffee grinder, bullet blender or blender).
  2. Pulse until a powder forms.
  3. Store in an airtight container. Use the following tips to keep your powder from clumping.

Tips for creating your own powders

  • Powder only as much as you need for a month or two. Sometimes, especially with fruit powders and onion powder, natural sugars can make clumping an issue (and there are even more ways to help stop clumping). So only can as much as you need at for a short tie and store the rest whole.
  • Use arrowroot powder to help keep onion powder from clumping. I use about 1 tsp per cup of powder, but you may find you need to make other adjustments.
  • Dry them again – you can put them back into your dehydrator to dry again before storing if you find that maybe they are clumping more than you are happy with while grinding. I prefer placing the onion on a cookie sheet in preheated oven (lowest temp) that is then turned off, for about 20 minutes.

Dried Onion Conversion

1 small onion equals 1/4 cup of minced dried onion equals about 1.5 tablespoons of onion powder.

Wooden tray with diced onion, dried minced onion, and onion powder

Frequently Asked Questions

Why Do Onions Turn Pink While Dehydrating?

This is caused by higher sugar content that is starting to caramelize and from over-processing of onions in food processors or with dull knives. Learn more about why onions turn pink while dehydrating.

More Dried Onion Ideas

Mason jar of dehydrated caramelized onion with a fresh onion on a wooden surface

How to Dehydrate Caramelized Onions + Onion Powder

Bulk French Onion Dip spice mix in a jar from overhead.

Bulk French Onion Dip Mix with Dried Caramelized Onions

Shredded onions in a jar on a table.

Why Do Dehydrated Onions Turn Pink? (How to Fix It)

A container of dried mirepoix with carrots and celery next to it.

Dehydrate Mirepoix and Make Mirepoix Powder

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A jar of dehydrated onions and DIY onion powder on wooden background with text: How to Dehydrate Onions and Make Onion Powder

How to Dehydrate Onion and Make Your Own Onion Powder

Learn how to dehydrate onions for perfect minced onions for meals, and make the most amazing tasting onion powder that is so much better than storebought!
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Ingredients

Instructions

To Dehydrate

  • Wash and peel onions
  • Slice into rings or chop into small dices
  • Dry at 125F / 52C for 10-18 hrs until they are crisp when cooled.
  • Condition
  • Store in an airtight container

To Powder

  • Place pieces into your favorite blender or coffee grinder
  • Pulse
  • Process until finley ground
  • Place onto cookie sheets in warmed (but off) oven to dry
  • Store in airtight container

Darcy’s Tips

Notes:
Many people find onions overpowering to dry inside, so opt to do in another room with windows open, or do it outside.
You can blanch the onions for a few moments beforehand to reduce the smell, or caramelize them completely for a different flavor.

Nutritional information is an estimation only. Nutrient information for dehydrated foods is based on fresh. Use 1/4 of the servicing size for the same nutrient information. Thus 1 Cup of fresh fruit has the same sugars as 1/4 dried.

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15 Comments

  1. If I dehydrate to hot will that reduce onion flavor?

    1. It can – or it can brown your onions some . That’s why we have recommended temps.

  2. Avatar for rutherford rutherford says:

    i’m planning to make a few soup mixes with some dehydrated foods, would dehydrated onions work well in a soup that originally calls for the onion to be sauteed?

    1. Yes – but you can also saute them (no oils), much like we do caramelized onions.

  3. When drying the onion powder in the oven, how long does it typically take?
    Thanks!

    1. As mentioned for powder, 20 min at the most for drying powder. If you mean drying onions – I can’t tell you – what is your oven’s lowest temperature and how you prepare them matter. Your issue is not burning them with too much heat – could be anywhere from 3 to 6 hours?

  4. Avatar for Sandy Woodbury Sandy Woodbury says:

    Do I need to cure the onions if I am going to dehydrate? Thanks!

    1. Curing is only if you are planning on storing the onions whole for a time. No curing needed if you’re going right to preserving through freezing or dehydrating or freeze drying.

  5. I have yet to try to dehydrate onions but I have made lots of jerky. I am curious how long dehydrated onions last and how to store them?

  6. Avatar for Jennifer S Jennifer S says:

    5 stars
    What type of onions are best for dehydrating, cooking onions or sweet onions like red or Vidalia?

  7. I just got a bunch of onions. I won’t use them all and want to dehydrate them. I’m in Florida and have a dehydrator but it is always humid. Can I still out the dehydrator outside or will the humidity mess that up?

    1. If your humidity is 70%+, you’ll have a harder time with it only because moving moisture from one saturated place to another slows down the process, but you can do it. It’ll just take longer.

    2. During monsoon season in Arizona, our humidity gets pretty high. I move my dehydrator to a room with a window unit A/C.

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