Like roasts and Justin Bieber, frozen vegetables need an image makeover. They have gotten a bad rap, but in reality, freezing your vegetables is an affordable way to access your favourite produce all year long, and in some cases, they retain nutrients even better than their fresh counterparts. The process, while more involved than freezing fruit, is still rather easy.
Why Freeze Vegetables?
Nothing beats eating a fresh vegetable, and yes, sticking vegetables in the freezer will change the texture of them. Still, it's the easiest way to preserve every bit of nutritional value in your vegetables without having to go through the more involved process of canning. It's useful if you have a glut of something seasonal: peas in the spring, corn and zucchini in the summer, carrots in the winter, and so forth.
Because almost all vegetables are flash-boiled before they're frozen, they will require less time to cook when you actually use them. Keep frozen broccoli on hand to toss into stir fries; stir a handful of peas into risotto; add carrots to thick stews. Or if you just want to keep things simple, steam any batch of vegetables gently over simmering water for a healthy addition to any meal.
A Basic Guide to Freezing Just About Every Vegetable
The biggest difference between freezing fruits and freezing vegetables is the process of blanching, or flash-boiling. The process of blanching stops enzyme actions which can cause loss of flavour, colour, or texture; it also brightens the colour of your vegetables (just look at the vibrant green colour of those peas!), cleans the surface of organisms, and helps slow the loss of nutrients. And after blanching, vegetables must be cooled quickly to stop the cooking process immediately.
Just like with frozen fruit, moisture and air are the biggest saboteurs of good frozen veggies, so make sure you keep them sealed and dry to the best of your ability!
- Select young, tender, crisp vegetables that are at their prime. The sooner they have been frozen after they have been harvested, the better they're going to taste. If you have a glut of peas and realistically know you won't be able to eat them all fresh, better to freeze them ASAP, rather than wait until they're over the hill.
- Wash them thoroughly.
- Blanch, or cook the vegetables in boiling water for a very short period of time (see below for more precise cooking guidelines).
- Shock your vegetables by removing them from boiling water and immersing them in a bath of ice and water until their temperature has come down and they are cool. I like to do this with a colander over the ice bath (see below).
- Pat your vegetables dry as thoroughly as possible. This is a really important part, otherwise your frozen vegetables could end up looking like this:
- Spread vegetables on a sheet tray until frozen solid, then transfer them to a heavy plastic freezer bag. After packing your vegetables, wipe the top of each plastic bag clean, and seal it as tightly as you can, "burping" the bag to expel any air before closing it. This'll prevent freezer burn and keep food from drying out. Label your bags with the date and the name of the product.
- Your vegetables are ready to use! To use them, defrost them, either in the refrigerator, or in a pan of cool running water. Thaw them within 6 months to a year, otherwise your vegetables could become prone to picking up off-flavours from your freezer.
Blanching Times, And Other Important Things To Remember
The step-by-step guide above is for just about every vegetable, but there are a few varieties that simply don't freeze well. Vegetables with a high water content, like cabbage, celery, cucumbers, endive, radishes, and lettuce, don't fare well in the freezer, so they will wind up limp and soggy if you try to defrost them. Other vegetables, like onions, change flavour; peppers, such as green bells, become bitter. Follow these guidelines and cooking instructions and you won't go wrong:
- Asparagus: Cut into desired lengths; blanch for 2-4 minutes.
- Avocado: Freezing avocado in the same manner as other vegetables will result in a mushy mess. Properly freeze an avocado by washing, scooping out, and puréeing avocado with a bit of lemon juice to prevent browning.
- Capsicums: do not freeze capsicums, as they change flavour during freezing.
- Broccoli: peel and trim stalks; cut florets off; blanch 3 minutes.
- Brussels Sprouts: Wash well and blanch 3-5 minutes.
- Cabbage: do not freeze.
- Carrots: Peel, slice or dice, and blanch for 3 minutes. Blanch baby carrots whole for 5 minutes.
- Cauliflower: Soak for 30 minutes in a salt water solution; blanch for 1-3 minutes in salted boiling water.
- Celery: do not freeze.
- Corn (kernels): Husk, de-silk, blanch 4-5 minutes, and cut from cob once cool.
- Corn (cob): Blanch 6-9 minutes.
- Cucumbers: do not freeze.
- Eggplant: Wash, slice and cube, and blanch for 4 minutes. Dry well.
- Endive: do not freeze.
- Green beans: line up the stem ends, slice off the stems, cut the beans into bite-sized pieces, and blanch for 2-4 minutes depending on bean thickness.
- Herbs: do not freeze sprigs of delicate, soft herbs, like basil, chives or parsley. Freeze hardier herbs like rosemary, thyme and oregano by cleaning, drying, chopping, and preserving in olive oil; freeze in ice cube trays before transferring to labelled zip-locked bags.
- Jalapeños: Wash and blanch whole for 2-3 minutes. Place in a bag that's been sealed as tightly as possible.
- Leafy greens like kale: Wash well; discard tough leaves and stems; blanch 2-3 minutes.
- Lettuce and other salad greens: do not freeze.
- Lima or other beans in pods: Shell, sort, and wash. Blanch for 2-4 minutes.
- Mushrooms: Clean well with a brush; blanch 3-5 minutes.
- Okra: trim stems but do not break pods. Blanch 3-4 minutes.
- Onions: Do not freeze onions as they change flavour during freezing.
- Potatoes: Potatoes don't freeze well as they tend to become mealy.
- Radishes: do not freeze.
- Snow peas: wash, remove strings and stems, and blanch 1-3 minutes.
- Spinach: trim and blanch 2 minutes. Wring out as much water as possible before freezing.
- Sprouts: do not freeze.
- String beans: Cut, slice, or leave whole; blanch for 3-4 minutes.
- Summer squash/zucchini: wash, cut into slices, and blanch 3 minutes.
- Tomatoes: Tomatoes don't freeze well as they tend to lose their flavour and become mealy. If you must freeze tomatoes, peel and quarter them; cover and cook until tender, about 10-20 minutes; place the pan in cold water to cool, and pack into containers, leaving about an inch of headspace. Seal and freeze.
- Turnips and parsnips: wash, slice, and blanch 3 minutes.
- Watercress: do not freeze.
So Is It Ever Worth Buying Pre-Frozen Vegetables?
If you don't have a surplus of vegetables to freeze or you're simply pressed for time, store-bought frozen vegetables do work in a pinch. Frozen spinach is most useful, especially when you're making a recipe like spanakopita that calls for very large amounts of spinach. (If you bought the vegetable fresh, you'd be buying bags and bags of spinach.) Vegetables like okra, which can be hard to find in my area outside of a certain season, are useful for dropping into stews; the same goes for peas, which I cook with a lot in risottos and fried rice, although when I can, I prefer to freeze my own peas whenever I have a chance as there's a big difference in texture. The biggest payoff is probably the fact that there's a plethora of vegetables, like cauliflower, and eggplant, that you can't get in the frozen section of your supermarket.
So if you're trying to figure out what to do with all that asparagus, what are you waiting for? Your freezer is most energy-efficient when it's full, after all.