Learn to blanch vegetables for dehydrating or freezing with these easy step by step directions for three different ways to blanch vegetables.
Why We Blanch Vegetables
The blanching process is used to scald vegetables in boiling water or steam for a specific amount of time. It stops enzyme actions which can cause a loss of flavor, color, and texture when the food is frozen or dehydrated.
It's also known as parboiling.
Blanching helps to rid the surface of food from dirt and organisms, it brightens the color and helps retain vitamins. Some vegetables are highly fibrous and taking the time to blanch them wilts, or softens them, so they will dry faster or be easier to package for freezing.
Blanching time is crucial and varies with the vegetable and size. Under-blanching vegetables can stimulate their enzymes and is worse than no blanching.
When water blanching, be careful and use the recommended times. Overdoing the blanching time will cause loss of flavor, color, vitamins, and minerals, so you will essentially transfer all the nutrients from the food to the boiling water.
Always Blanch These Vegetables
These vegetables will always require blanching. You should only use vegetables that are in excellent condition. With most larger vegetables, prepare to the size you want first, then blanch.
Once you’ve completed the blanching process (including the ice water bath), food can be stored in the freezer or processed in a dehydrator.
- Asparagus – 4-5 min.
- Beets (diced or sliced) – 4-5 min.
(Roasted or cook whole, then dice or slice does not need blanching time)
- Broccoli – 3-4 min. **
- Brussell Sprouts (halved) – 5-6 min.
(leaves alone do not need to be blanched)
- Carrots & Parsnips (rounds) – 4 min.
- Cauliflower – 4-5 min.
- Celery – 4 min. **
- Corn – 4-6 min.
- Eggplant – (large pieces) 4 min.
- Green beans – 4 min.
- Potatoes – 7 min.
- Rhubarb – 2 min.
- Sweet Potatoes and Yams – 7 min.
- Winter Squash -- 4 min.
** These items fall under my guideline of - "if you eat them raw, you do not have to blanch them." However, texture can be affected, as well as an eventual loss of color.
So in the case of celery - it does not have to be blanched, and the eventual color does fade. The resulting rehydrated celery has more of a toothy bite to it than the blanched celery, so that is a personal choice for you.
Oven option: Root vegetables (except radishes or onions or garlic) should be cooked or blanched first. You can cook/roast sweet potatoes, beets, rutabagas and turnips, put them in the fridge for a few hours, then slice or dice them.
A note about frozen vegetables: If you are using commercially frozen vegetables to dehydrate, you do not need to blanch first. That has been done for you.
A note about vegetable powders: If your eventual goal is a powder, except for root vegetables, blanching is not always necessary, though, for fibrous vegetables, blanching is helpful.
Boiling Water Blanching
To make blanching easy, consider creating a blanching station to make the process go a bit faster. Begin by making an assembly line from your stovetop to your sink.
- A large stockpot, deep enough to submerge the food
- A clean sink, large bowl, or plastic tub
- Several clean towels
- Cold water
- Ice (as many pounds of ice as you have vegetables)
- A slotted spoon for removing the vegetables from the pot. I love using a small spider as it removes so much water!
- Bring a stockpot filled with water to a rolling boil.
- Fill your kitchen sink, a large bowl, or a tub insert with cold water and ice.
- Place a small batch of vegetables in the boiling water for the recommended time
- After the allotted time, promptly submerge the vegetable pieces in a cold water bath using the slotted spoon. Change water frequently or use cold running water or ice water. If ice is used, about one pound of ice for each pound of vegetable is needed. Cooling vegetables should take the same amount of time as blanching.
- Once the blanched vegetables are cooled, remove them from the ice water and place them on a clean kitchen towel to pat dry. If you plan to dehydrate the food, remove as much water as possible. Leaving extra water on the food will extend the drying time. If you plan on freezing, place in single layers on trays, flash freeze, then store in airtight containment for the freezer.
- Process the food for drying on dehydrator trays.
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Heating in steam is an alternative to water bath blanching and is even recommended for a few vegetables. Try this method for broccoli, pumpkin, sweet potatoes, and winter squash, which will help them keep their texture better. Steam blanching is not quicker than boiling water blanching, in fact, takes about 1½ times longer to get the vegetables to the proper state.
To steam blanch, use any pot with a tight lid that has a basket that will hold the food at least one inch above the boiling water in the pot. It only takes an inch or two of water in the pot to make steam. Bring the water to a boil and monitor it after each batch to make sure your pot does not go dry.
Put the vegetables in the basket in a single layer so that steam reaches all parts quickly. Cover the pot and keep the heat high. Start counting steaming time as soon as the lid is on. Try one of these kitchen hack alternatives if you do not have a steamer basket.
See this article from NCHFP for recommended blanching times for many common vegetables.
Microwave blanching may not be effective since research shows that some enzymes may not be inactivated. This could result in off-flavors and loss of texture and color with the finished product. [source] On the other hand, there seems to be some vitamin retention when using this method [source], since microwaving does not completely submerge the food into boiling water which can remove part of the nutrients.
If you want to try the microwave blanching method, be sure to work in small batches and use the directions for your specific microwave oven. Microwave blanching will not save your time or use less energy.
Use these blanching directions from GE Appliances to get started with microwave blanching.
Don't Waste That Water!
While blanching, a few nutrients are lost into the water. But don't waste it! You can still use that water in other ways!
- Cook rice, couscous, or quinoa;
- Use as the beginning of a stock or soup base;
- Use as the water in any recipe;
- Water plants or garden after it has cooled.
Can Blanching be Used on Fruit?
In some cases, blanching can actually help with thick skinned berries by breaking the skins to make dehydrating a little faster. While you can also freeze or cut, blanching is a great way to do it for a large quantity.
Try blanching on these fruits: