Northern Alberta Institute of Technology

How to blanch and freeze vegetables

A Culinary Arts expert explains this simple – but delicate – process

Many things mark the winding down of summer in Alberta – earlier sunsets, chillier mornings and evenings, and the changing colour of tree leaves.

To that list you could add green-thumbs harvesting the garden so as to not let the fruits – and, more specifically, vegetables – of their labours go to waste.

Preservations techniques are essential. These can take many forms, from pickling to making jellies to fermenting hot sauces and more.

But you can only eat so many pickles and preserves. Sometimes, all you want during the cold, snowy months are a hearty soup or stew that demands whole veggies. That’s where blanching and freezing come in.

According to Linda Sutherland (Culinary Arts ’18), lab technician for the Culinary Arts program, blanching before freezing specific vegetables will help maintain their flavour and nutrients.

“It’s the best way to keep the vegetables as fresh as possible,” she says.

While it sounds simple, blanching can be a delicate process. We asked Sutherland for tips on this time-honoured harvesting method to help gardeners enjoy their produce through to the next planting season.

How to know what can be blanched

cooked green beans

“You don’t blanch everything,” says Sutherland.

If it’s green, such as green beans, shelled peas, broccoli and brussel sprouts, it should be blanched before freezing. That said, you can add cauliflower, other beans, and carrots to that list.

(Sutherland suggests enjoying carrots straight from the refrigerator for as long as possible before blanching and freezing; they keep well on their own and simply taste better when fresh.)

Sutherland adds that the harvesting of the blanch-friendly vegetables doesn’t have to wait for the end of summer. It can be done the moment the plants are ready to be picked.

“The basic rule is, if it’s big enough and ripe to eat, you can harvest it. And then keep doing this until the plant dies.”

Fruits don’t need blanching before freezing, she adds. Nor do squash or zucchini. If you can’t use them fresh, just dice or purée them before they hit the freezer.

The art of blanching

blanched green beans in ice-water bath

“The goal of blanching is to keep your vegetables pristine,” says Sutherland, “not to cook them.”

It’s a simple process but a delicate balance. Sutherland suggests these steps:

  1. Prepare a pot of water large enough to fit your yield.
  2. Prepare a separate ice-water bath.
  3. For most vegetables, salt the pot of water; for white vegetables like cauliflower, use a little bit of vinegar or lemon juice instead. (Linda suggests one tablespoon of salt or acid per four to six litres of water.)
  4. Bring the pot of water to a roiling boil.
  5. Add your prepared vegetables (cleaned, shelled, cut, etc., as required).
  6. Boil for no longer than a minute.
  7. Remove vegetables immediately to ice bath to stop cooking.
  8. Let the vegetables cool in the water.
  9. Drain.
     

“If done successfully, your vegetables will have a nice, bright colour – especially the green vegetables – and will retain some firmness.”

This is the most common method, but Sutherland says you can also use a microwave on a very short steam cycle before submerging into the ice bath.

The art of freezing

bag of frozen peas

For best results, says Sutherland, lay a single layer of the blanched vegetables on a cookie sheet and lay it flat in the freezer.

“This will prevent the vegetables from clumping together,” says Sutherland. Once they’re frozen – in 15 to 30 minutes – put them in a freezer-safe bag or container.

Some freezers are better than others. In a refrigerator freezer, where you’re frequently opening the door, vegetables have a shorter shelf life – up to six months. In a chest freezer that isn’t accessed as much, frozen produce should last a year.

Don’t be afraid to make mistakes

freezer full of frozen vegetables and soup

If you’re nervous about getting it right, Sutherland recommends practising with vegetables you have a lot of and perhaps a smaller batch. If things don’t work out, you’ll know it: they’ll slowly pale even when frozen, then turn slightly brown when thawed, losing some taste, texture and nutrients.

Generally, however, they are not inedible once you prepare them in whatever way you choose.

“If you mess up one batch, who cares!” says Sutherland. “Maybe you won’t want to serve it to guests, but you can certainly eat it yourself.

“The main thing is to not be afraid,” she adds. “Keep on trying until you get it right.”

Once you do, you’ll be on your way to enjoying nearly-fresh, homegrown vegetables all year long.


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