Freezing vegetables
Medium term storage
- Select high quality, fresh, young, tender, ideal maturation (not tough, starchy or woody)
- Asparagus, beans, peas, spinach, whole kernel corn and mashed squash freeze well
- Corn on cob can develop off flavours unless blanched for the correct time. Celery, lettuce, tomatoes and cucumbers become limp on thawing – unless tomatoes pureed for sauce or cooked slightly for use in soups and stews. Eggplant darkens and becomes watery.
- Carrots and parsnips can be frozen but best to store in a cool room.
- Cooked beets and raw onions are best frozen sliced or diced as the texture will become rubbery and limp on thawing.
- Wash, blanch and pack.
- Vegetables may be stored for 1 year at -18°C
Almost all vegetables require blanching before freezing, with a few exceptions. Blanching is a process where food is plunged first into hot boiling water and then cooled rapidly in ice water to stop the cooking process. Blanching kills enzymes, which cause fruits and vegetables to ripen and cause undesirable changes in food flavour, colour and texture. Make sure to follow exact blanching times for each type of vegetable. Under-blanching does not destroy all the enzymes while over-blanching overcooks and reduces flavour and nutrient content.
To blanch you will need a large kettle with a cover (4 L water to about 500 g vegetables or 8 L for leafy greens). Place vegetables in wire basket or tie loosely in cheesecloth bag leaving length of string for ease of handling. Lower vegetables into vigorously boiling water, cover and immediately start counting blanching time. Keep heat on high so water quickly returns to a boil. Once blanching time is up, chill vegetables immediately in cold running water. If water is not cold enough then add ice. Leave vegetables in cooling water for same time used in blanching but no longer than necessary. Drain cooled vegetables thoroughly and pack in freezer containers (label and date) and place in freezer.
Make sure to follow exact blanching times for each type of vegetables as under-blanching does not destroy all enzymes while over-blanching overcooks and reduces flavour and nutrient content.
Table: Preparing and packing vegetables
|
Vegetable |
Preparing |
Blanching |
Packing |
|
Asparagus |
Remove tough ends. Cut in uniform lengths |
Med – 3 min Lrg – 4 min |
Chill, drain and pack |
|
Beans (green/wax) |
Trim ends. Leave whole or cut in 3 cm pieces |
Cut – 3 min Whole – 4 min |
Chill, drain and pack |
|
Beets |
Leave root ends on; cut off tops leaving 3 cm stems. Cook in boiling water until tender. Cool. Peel and slice |
None |
Pack |
|
Broccoli |
Remove woody stems and trim. Cut through stalks so that pieces are not more than 3 cm across |
Med – 3 min Lrg – 4 min |
Chill, drain and pack |
|
Brussel Sprouts |
Trim stems and outer leaves |
Sm – 3 min Med – 4 min Lrg – 5 min |
Chill, drain and pack |
|
Cabbage |
Trim outer leaves and core. Cut in wedges or shred coarsely |
Wedges – 2 min Shredded – 1 min |
Chill, drain and pack |
|
Carrots |
Remove tops and scrape or peel. Leave small carrots whole. Cut larger carrots in 1 cm slices or dice or cut lengthwise in fingers |
Cut – 3 min Whole – 5 min |
Chill, drain and pack |
|
Cauliflower |
Break heads into small flowerets about 3 cm in diameter |
3 min |
Chill, drain and pack |
|
Corn – whole kernel - on cob |
Remove husks and silk Remover husks, trim cobs to even lengths |
4 min Sm – 7 min Med – 9 min Lrg – 11 min |
Chill, cut kernels from cob. Pack Chill, drain and pack |
|
Herbs |
Chop |
None |
Freeze on tray before packing |
|
Mushrooms |
Slice. Sauté 500 ml in 30 ml butter 4 min |
None |
Drain and pack |
|
Onions |
Remove outer skin, root and stem ends. Chop |
None |
Pack or freeze on tray before packing |
|
Parsnips |
Remove stem and root ends. Peel. Cut in 2 cm fingers or 1 cm slices |
Fingers – 1 min Slices – 1 min |
Chill, drain and pack |
|
Peas |
Shell |
2 min |
Chill, drain and pack |
|
Peppers |
Leave whole or remove seeds and half stems, cut in half or chop |
None |
Pack dry or freeze chopped pepper on tray before packing |
|
Pumpkin |
Cut or break apart, remove seeds and fibers. Cut in chunks. Steam, boil or bake until tender. Cool and scoop from rind. Mash or sieve |
None |
Pack |
|
Spinach, Chard |
Wash thoroughly. Cut chard in 3 cm pieces or separate leafy parts from stalks and cut stalks in 10 cm lengths |
2 min |
Chill, drain and pack |
|
Summer squash |
Cut in 1 cm slices |
2 min |
Chill and drain. Freeze on tray before packing |
|
Winter squash |
Cut in pieces and steam, boil or bake until tender. Cool, scoop from rind and mash Peel and dice (butternut)
|
None 2 min |
Pack Chill, drain and pack |
|
Tomatoes |
Peel by dipping in boiling water for 30 – 60 seconds, cooling in cold water and gently slipping off skin. Cut in quarters. Add 5 ml salt, dash pepper and 5 ml sugar to 1 kg tomatoes and cook gently until tender (5-6 mins) |
None |
Pack |
|
Turnip |
Peel, dice and boil until tender. Mash Peel, dice and blanch |
None 2 min |
Pack Chill, drain and pack |
Ref: Ontario Ministry of Agriculture and Food. (1990). Freezing Foods. Food Advisory Services. Canada Department of Agriculture.