Here’s how to dehydrate onions in a dehydrator. This is a great option when you have a lot of onions or want to take advantage of a bulk deal on onions.
Can You Dehydrate Raw Onions or Should You Blanch Them?
Good news! You do not need to blanch onions before dehydrating. Onions can be dehydrated raw.
That said, blanching onions will reduce the smell while dehydrating, shorten the time needed to dry them and prevent discoloration. If those are important to you, see how to blanch them in the reducing odour section below.
Is Freezing or Dehydrating Onions Better?
Ooh, tough question. I do both and recommend both! Both are healthy ways to preserve onions with minimal nutrient loss.
I like to freeze onions when I have just a few onions that need to be used up or when I’m tired of constantly chopping fresh onions! It’s so handy to have frozen chopped onions on hand. I also use this method when I can’t dehydrate onions due to our Canadian winter weather. (I dehydrate onions outside due to their smell, which is not fun when it’s -30°C/-22°F!)
Dehydrating onions is great when you can get good deals on fresh onions. Dried onions will last a long time and they re-hydrate beautifully. Your dinner guests won’t have a clue that the onions you used were dehydrated. So, when you can get a good deal on beautiful fresh onions and you can easily move your dehydrator outside – dehydrate them!
And now to blow your mind – you can dehydrate frozen onions! Yup, go ahead and buy frozen onions and dehydrate those!
Steps to Dehydrate Onions in a Dehydrator
1.Peel & Cut Onions
- Cut off the tip and root of onion and peel off skin. Watch How to Cut Onions for Tips.
- Slice or dice your onions. I prefer to slice onions to retain best flavour and because that’s the most common way I use onions in recipes. When I need smaller pieces I can easily crumble them into smaller pieces.
- Just be consistent in size and try to keep them thinner than 1/4 inch.
PRO TIP: Most aromatic foods like onions, garlic and herbs will keep their flavour longer when left in larger pieces.
Caution: You can use a food processor to slice (use slicing blade) or dice (use regular knife blade) your onions, just be careful not to turn them into a liquid pulp. However, if this does happen, pour off some of the liquid and pour the onions on a liner or on parchment paper over top of the mesh on your dehydrator trays. The onions may dry into a sheet (kind of like fruit leather). Once it’s dry and brittle you can turn it into onion powder by pulverizing in your food processor.
2. Place on Trays
Separate onion rings and place on mesh drying screens. Spread out in a single layer, but don’t fuss too much, it’s okay if they overlap a little bit.
Set the dehydrator to 155°F or 68°C as recommended in my Excalibur dehydrating book. Higher than most vegetables, but I’m following what my dehydrator manual recommends (check your manual to see what it recommends). It will take 7-12 hours depending on how humid it is, how many onions you’re drying at one time, how thick the onions are, outside temperature, etc.
I filled 6 Excalibur dehydrator trays with 5lbs/2.2 kg of sliced onions – about 15 onions.
4. Check for Dryness
Onions are done and completely dehydrated when they crinkle and easily break or crush. If they’re bendable but don’t break, give them a little more time. Listen here for the sound of dried onions.
5. Cool & Store Dried Onions
Let cool completely then place in an air tight container that is just large enough to hold all of your dried onions. A container with a lot of empty space traps too much air which will reduce the flavour and colour more quickly.
Store the container in a cool, dry, dark place. Read more on How to Store Dehydrated Food.
PRO TIP: After dehydrating onions in your dehydrator, consider following it with a batch of potatoes or some other savoury food. A wee bit of onion flavour would go much better with potatoes than apple rings, don’t you think!
How to Use Dried Onions
Dehydrated onions can be used whenever a recipe calls for fresh onions. Just remember this general formula:
4 tablespoons of dried onion slices = 1 diced medium, fresh onion
Re-hydrate the onions for recipes where cooking time is short and there isn’t a lot of liquid.
For soups, stews, chilis and curries where there is a lot of moisture you can simply crumble the dried onions and use without rehydrating.
- Make your own Onion Soup Mix, perfect for onion soup dip.
- Use a grinder and turn your dried onions into homemade onion powder.
- Use flakes or powder in savoury baking recipes like cheese scones, cottage cheese dill bread, cheddar chive rolls, chia crackers, etc.
- Use in seasoning blends or when making finishing salt.
- Use in dried food mixes like Scalloped Potatoes, Homemade Onion Soup Mix, Soup Mixes in a Jar or in some of the backcountry meals found in my Homemade Backcountry Meals Cookbook.
How to Re-Hydrate Dried Onions
You don’t have to re-hydrate dried onions – you can just crumble them or turn them into powder to use. However, re-hydrating is super easy and allows you to use dried onions just like fresh onions in cooked recipes.
1/4 cup dried onion slices = 1 medium raw onion = 1 cup sliced onions
- Measure the amount of onion needed into a bowl.
- Pour hot water over the top to cover and let rest for ~30 minutes for the onion to absorb the water.
- Drain and use like you would raw onions as indicated in recipe.
Reducing the Smell of Drying Onions – How to Blanch Onions
The smell of dehydrating onions is very intense and will penetrate into just about everything. Be cautious about where you set up your dehydrator.
If you cannot move your dehydrator outside or you’re using the oven there is a work around to the odour issue. Blanching your onions before dehydrating will reduce their odour. Here’s how to blanch onions:
- bring large pot of water to boil
- cut your onions to desired size – sliced or diced
- add your onions to boiling water for 30 seconds
- remove from boiling water directly into an ice water bath to stop them from cooking further
- drip dry and pat dry as much as possible
- continue with dehydrating process
Bonus: After blanching, the onions will dehydrate quicker.
What about smelly fingers and cutting boards? Read How to Combat Tears and Onion Smells.
Frequently Asked Questions about Dehydrating Onions
Are Dehydrated Onions as Healthy as Raw Onions?
Yes, don’t let concern over minor nutrient loss stop you from dehydrating onions. Generally speaking dehydrated food keeps its nutritional value thanks to low heat. Dehydrating may reduce some of the Vitamin C and B in onions, but the fibre, antioxidants, calcium, potassium and magnesium remain.
What’s the Best Way to Store Dried Onions?
Store in an airtight glass jar in a dark, dry, cool space like a pantry. Glass jars seal tightly and don’t absorb odours.
Reduce exposure to the enemies of freshness for all stored food. Read How to Store Dehydrated Food.
How Long do Dried Onions Last?
Dried onions will last for years if they’re stored properly. Keep them air tight, dark and at consistent cool temps. You may notice the colour start to become a little yellow and flavours may get a little less flavourful after 12 months.
You’ll get the best flavour if you use them within a year.
Using oxygen absorbers can help extend the shelf life of dried food. If you’re serious about storing your dried onions for more than a year, it’s worth considering. Using mylar bags is another good option if you intend on storing your dried food indefinitely. But, if you plan to use your onions within a year, neither one of those options is necessary.
Why did my Dried Onions turn Pink?
It’s common for onions to turn a little yellow or pink when dehydrated raw. It’s the sugars in onions caramelizing, it’s perfectly safe and not noticeable in most recipes.
To prevent discolouration, either blanch onions or dry at a lower temperature.
Can you Dry Onions in the Oven or Microwave?
Honestly, I don’t think it’s worth it. Sure it can be done, but it will take a long time, be smelly and you’ll only be able to do small batches. I would recommend freezing onions instead if you don’t have a dehydrator.
Watch My Dehydrating Onions Video
Here’s a short video showing you just how easy dehydrating onions can be. Notice, you do not need to blanch or pre-treat onions in any way – just chop and dry. This was one of my very first videos – enjoy the throwback to the good old days!
Recipe for Dehydrating Onions
How to Dehydrate Onions
- 5 lbs onions 2.2 kg
- Cut and peel onions. Slice into consistent size pieces no thicker than 1/4 inch.
- Separate slices and place evenly in a single layer on mesh dehydrator tray. Some overlapping is okay.
- Set dehydrator to 155°F or 68°C and dry for 7-10 hours or as needed until onions are crunchy and crumbly.
- Check for dryness at 6 hours and rotate trays. Onions should be brittle and crumbly. If they're just bendable, dry them a little more.
- Cool completely (let rest for 2 hours) then pour into a air tight container just large enough to hold all the dried onions (avoid large airspace). Do not crumble until ready to use.
Nutrition Facts (per serving)
Getty Stewart is a Professional Home Economist, speaker, frequent media guest and writer dedicated to putting good food on tables and agendas. She is the author of several recipe books on enjoying and preserving fruit, Founder of Fruit Share, a mom and veggie gardener. Sign up to get articles by Getty delivered to your inbox. You’ll get recipes, practical tips and great food information like this.