How to Dehydrate Onions
{White, red, yellow}
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Dehydrated onions add rich flavour to dehydrated meals, soups, stews, and pasta dishes. They’re also perfect for making spice blends, rubs, or homemade onion powder.Â
Snapshot
Special Prep
Blanch (optional)
Temperature
135°F
Time
8-12 hours
Mass Change
Approx 90% decrease
How to prep onions for dehydrating
Blanching onions before dehydrating is optional, but it has some benefits:
- Softens sharp and bold onion flavours (this may be desired for certain uses, particularly for white onions)
- Slightly improves rehydration texture
- Preserves colour
- Reduces drying time
Here’s a basic guide on how to blanch onions for dehydration:
Prepare: Peel and slice the onions into 1/4″ thick rounds (or dice, or mince – see notes below)
Blanch: Bring a pot of water to a boil and immerse the onions in the boiling water for a short period, about 30 seconds. The exact blanching time may vary, so it’s important to monitor the process closely (onions should be slightly soft but not mushy)
Cool: Immediately cool by rinsing with cold water or transferring to a cold or ice water bath. This helps further retain the colour and texture of the onions.
Drain: Once cooled, drain the excess water from the onions.
Dehydration: Proceed with the dehydration process.
Pro tip:
Note: For diced or minced onion, I recommend slicing them into 1/8″ – 1/4″ thick rounds (rather than dicing or mincing) before dehydrating. Once dried, chop or mince them into your desired size. This method ensures consistent thickness for drying, retains more of their flavour and makes it easier to arrange the onions on the trays for optimal airflow.
How to dehydrate onions
Basic Steps:
- Slice, chop or mince onions into the desired size or shape (but no more than 1/4″ thick; see note above)
- If slicing rounds, separate the ringsÂ
- Optional: blanch for about 30 seconds; onions should be slightly soft but not mushyÂ
- If blanching: cool by rinsing with cold water or immersing in a cold or ice water bath
- Drain and arrange on a mesh lined dehydrating tray with enough room for air to circulate between the pieces (avoid over lapping)
- Place in dehydrator and dehydrate at 135°F for about 8 hours (blanched) to 12 hours (raw)
It’s that easy!
Notes:
- A mesh liner is required for diced or minced onions
- Dehydrating times may vary (the water content in the onions, as well as the humidity and altitude of where you live in impact the time)
- To learn more about dehydrating, check out our post How to Dehydrate: Learning the Basics
How do you know when onions are fully dehydrated?
Onions will be dry, lightweight and brittle. No moisture should excrete when split in half and squeezed.
Jar test: If eager, you can place your onions in a glass jar and tightly close the lid. If you notice moisture or condensation forming in the jar within 24-48 hours (or if the onions become tacky) you know there is still moisture and more dehydrating time is needed.Â
Note: You technically can’t over dehydrate onions. If in doubt, dehydrate until you’re absolutely certain there’s no moisture left.Â
Fresh to dehydrated conversion measurements ​
90%
The mass and weight of onion decreases by about 90% once dehydrated.
Ex. 1 medium onion
- Pre-dehydrated:Â 132gÂ
- Dehydrated:Â 15gÂ
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How to store dehydrated onions:
Here are some tips to help you maximize the shelf life of your dehydrated onions:
- Allow to cool after dehydrating before storingÂ
- Keep stored in a sealable container or bag in a cool, dry and dark place
- Using Mylar bags or vacuum sealing can extend the shelf life by up to three times its normal duration! This is useful if you’re prepping lots for longer term use. Learn the pros and cons of each in our post: The Ultimate Guide to Long-Term Food Storage: Mylar Bags vs. Vacuum Sealing (Bags & Jars)
When dried and stored properly, onions should have a shelf life of several years.
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Some of our recipes with dehydrated onions:
Rehydrating Dehydrated Ingredients
When & Why to Rehydrate Dehydrated Ingredients
Knowing how much water to use for rehydration is essential for getting the best texture and flavour out of your dehydrated foods. Some ingredients are best rehydrated just before use, while others can absorb enough liquid during cooking – it all depends on how you’re using them!Â
For Dehydrated Meal Prep
- When preparing dehydrated meals for outdoor adventures, understanding the water requirements for different ingredients ensures you add just the right amount, giving you confidence in your meal creativity and preparation.
Before Cooking or Baking
- If a recipe doesn’t contain much liquid – such as stir-fries or casseroles – rehydrating beforehand prevents ingredients from staying too tough
- Pre-soaking reduces cooking time, especially for hard ingredients like beans or root vegetables
- Certain dehydrated ingredients (such as whole mushrooms or tomatoes) regain a better texture and flavour if rehydrated before cooking
- Rehydrated ingredients absorb flavors more easily when cooked, making dishes more flavorful
- Baking: Ingredients like dried fruits can be rehydrated to have a softer texture and to prevent them from drawing moisture out of the dough or batter
For Eating Raw
- If you’re eating the dehydrated ingredients uncooked, but prefer a softer texture (such as using dehydrated fruits or vegetables in a salad)
Rehydrating Dehydrated Onions:
Dehydrated onion to water ratio is typically 1 : 1 – 1.25
 Per 1/4 cup of dehydrated onion:
Quick Simmer
- Add 1/4 cup water and bring to a boil
- Turn down heat, cover and simmer for 5 minutes
- Turn off or remove from heat and let sit for 2-3 minutes
Just Add Hot Water
- Add 1/4 cup boiling water and stir
- Let soak for 12-15 minutes
Add water & refrigerate
- Add 1/4 cup boiled water and stir
- Allow to cool, place in fridge and let soak for 24 hours
Note: it’s important to not let sit for more than 30 minutes in room temperature because of the risk of bacteria growth.
FAQs
Can I use frozen onions?
Yes, you can dehydrate frozen onions! As a bonus, there’s no need to thaw them before dehydrating. Just make sure to break apart clumps that are frozen together.Â
Can I use an oven to dehydrate onions?
Not unless your oven can maintain a low temperature of around 135°F (57°C). Onions need to be dehydrated at this temperature to dry properly. If the temperature is too high, you risk either cooking the onions or causing “case hardening,” where the outer layer hardens, trapping moisture inside and preventing proper drying.
How to Dehydrate Onions {White, red, yellow}
Dehydrated onions add rich flavour to dehydrated meals, soups, stews, and pasta dishes. They're also perfect for making spice blends, rubs, or homemade onion powder.Â
Notable Equipment
- 1 Dehydrator
Ingredients
- Onions, white, red or yellow
Instructions
- 1. Slice, chop or mince onions into the desired size or shape (but no more than 1/4" thick; see note above)If slicing rounds, separate the ringsÂ
- 2. Optional: blanch for about 30 seconds; onions should be slightly soft but not mushy (see notes for purpose of blanching)
- 3. If blanching: cool by rinsing with cold water or immersing in a cold or ice water bath
- 4. Drain and arrange on a mesh lined dehydrating tray with enough room for air to circulate between the pieces (avoid over lapping)
- 5. Place in dehydrator and dehydrate at 135°F for about 8 hours (blanched) to 12 hours (raw)Place in dehydrator and dehydrate at 135°F for about 8 hours (blanched) to 12 hours (raw)
Notes
- A mesh liner is required for diced or minced onions
- Dehydrating times may vary (the water content in the onions, as well as the humidity and altitude of where you live in impact the time)
- To learn more about dehydrating, check out our post How to Dehydrate: Learning the Basics
- Softens sharp and bold onion flavours (this may be desired for certain uses, particularly for white onions)
- Slightly improves rehydration texture
- Preserves colour
- Reduces drying time
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The Foodie Behind the Screen
Hi there! I'm Bri. I'm sharing my love for cooking - and the outdoors - one recipe at a time.
