Freezing is an inexpensive way of preserving food that saves preparation time later if done in recipe sized portions. The biggest expense in freezing is the initial cost of the freezer, but once purchased operation costs are minimal. Best of all it’s usually quicker than canning.
Freezing preserves flavour, colour, texture and nutrients but is only suitable for foods cooked before eating- not for vegetables with a high water content such as celery cucumbers, lettuce, onions and radishes.
To maintain quality it’s best to harvest foods in the early morning and freeze as soon as possible afterwards. If the produce is purchased it is best to freeze within 6-12 hours of harvesting. For maximum nutrient retention plan on blanching. Set up the kitchen factory fashion and work quickly.
Select containers that exclude air, prevent moisture loss and contamination. If using plastic bags make sure all air is expelled and seal them tightly with elastic bands or twist ties. Jars are not recommended because they crack or break easily.
Many people say they don’t blanch vegetables before freezing but there are many scientific reasons to do so. Blanching inactivates the enzymes which help vegetables ripen and mature. If allowed to continue this process, the enzymes eventually produce adverse changes in colour, flavour and texture. Blanched vegetables have better colour, flavour, taste and a crunchier texture. See methods and charts below.
Place vegetables in a steam basket over boiling water using time table below.
Cool by plunging into cold water.
Dry on a tea towel or in a lettuce spinner.
Package leaving headspace.
Prepare two pots of boiling water.
Blanch 2 cups of vegetables at a time placed in strainer.
Immerse a few seconds in first pot, long enough to heat vegetables through, remove.
Immerse in second pot counting time when water returns to boil.
Follow blanching chart below.
Cool immediately in cold water to stop cooking, dry by using a fan and pack into containers leaving headspace.
Some vegetables, such as beets, squash, turnips and sweet potatoes do not require blanching because they are frozen fully cooked. Cook frozen vegetables about one third as long as fresh.
If you use your microwave to blanch it is possible to handle small amounts of vegetables as they mature. It will keep the kitchen cooler but it doesn’t eliminate any steps.
Follow the microwave blanching chart below.
Prepare vegetables as you would for serving, keeping pieces relatively small.
Use 2 cups (500 mL) amounts and 1/3 to 1/2 cup of water (75-125 mL).
Cover casserole and microwave on high for half the minimum amount of time.
Check, stir, and cover. if all vegetables are not an evenly bright colour, recover and cook maximum time.
Drain, chill, pack and freeze.
Select high quality vegetables that are young, tender and at the ideal stage of maturity for good eating.
Freeze vegetables within a few hours of picking.
Choose varieties with a lower water content: asparagus, beans, peas, beets, kohlrabi, rhubarb, squash and corn. Cabbage, peppers, spinach and Swiss chard freeze moderately well.
Blanch vegetables before freezing. Enzymes, naturally present in vegetables, must be inactivated by blanching to preserve colour, texture, flavour and nutrients during storage.
Blanching times are specific for each vegetable. Follow blanching times exactly.
To blanch: use two large saucepans filled with boiling water. Place a small amount of vegetables in a colander or wire rack which will fit inside the pot and can be lowered into it. Immerse the rack in the first saucepan just long enough to heat the vegetables, and then transfer them to the second pot. Start counting blanching time as soon as the water returns to a boil. When the specified time is up, remove the rack from the boiling water.
Plunge the rack or vegetables into ice water or place them under cold running water. Gently move the vegetable around in the water to speed the cooling process. Drain the vegetables as much as possible so ice crystals will not form. Use a lettuce spinner to drain the vegetables.
Pack drained vegetables in clean moisture- and air-proof plastic bags or airtight plastic containers, which will protect food from freezer burn and flavour absorption. Leave 1 cm (1/2 inch) headspace in rigid containers for expansion of produce during freezing. Press as much air out of bags as possible.
For freezing a mixture of vegetables, cut and blanch each vegetable separately. Mix and pack the quantity you require for each package.
For microwave blanching, use small quantities of vegetables and water in a covered bowl and microwave in two stages. Microwave on High for half of the minimum time required; stir; microwave on high for the second half of the minimum time. If the vegetable is not an even colour, cover and microwave the maximum length of time. Drain, chill, drain again, pack and freeze.
Label and date food so you can rotate stock efficiently. Keep a freezer log book.
Freeze by spreading packages out in the freezer or placing in the fast freeze compartment. Store frozen vegetables at -18(C (0(C), 8-12 months.
Microwave Blanching Times
Power Level: High (10)
Vegetable Amount Water Time (Minutes)
Asparagus 500 g (1 lb) cut into 2.5-5 cm (1-2 inch) pieces 50 mL (1/4 cup) 3 – 4
Beans, Green or Wax 500 g (1 lb) 125 mL (1/2 cup) 4 – 6
Broccoli 1 bunch, 600-750 g (1 1/4 – 1 1/2 lb), cut into 2.5 cm (1 in) florets 125 mL (1/2 cup) 4 – 5 1/2
Brussels Sprouts 250 g (10 oz) 50 mL (1/4 cup) 3 1/2 – 4
Carrots 500 g (1 lb), cut into 5 mm (1/4 inch) cubes 125 mL (1/2 cup) 4 1/2 – 6
Cauliflower 1 head cut into 2.5 cm (1 inch) florets 125 mL (1/2 cup) 4 – 5 1/2
Corn on the Cob Corn cut from 4 ears (cool by setting casserole in ice water) 50 mL (1/4 cup) 4 – 5
Onions 4 medium, quartered 125 mL (1/2 cup) 3 – 4 1/2
Parsnips 500 g (1 lb), cubed 50 mL (1/4 cup) 2 1/2 – 4
Peas 1 kg (2 lb) or l litre (4 cups) 50 mL (1/4 cup) 3 1/2 – 5
Spinach 500 g (1 lb) None 2 1/2 – 3 1/2
Squash, Summer, Yellow 500 g (1 lb), sliced or cubed 50 mL (1/4 cup) 3 – 4 1/2
Turnips 500 g (1 lb), cubed 50 mL (1/4 cup) 3 – 4 1/2
Zucchini 500 g (1 lb), sliced or cubed 50 mL (1/4 cup) 3 – 4 1/2
Note: Times will vary according to the wattage of the oven. Blanching is complete when a uniformly bright colour is achieved.
Preparing, Blanchign and Packing Vegetables
Vegetable Preparation Blanch (Minutes) Pack
Asparagus Remove tough butts and sandy scales. Cut in uniform lengths.
Medium – 3
Large – 4
Beans, Green or Wax Trim ends. Leave whole or cut in 3 cm (1 1/4 inch) pieces or lengthwise in strips Cut – 3
Whole – 4 Chill/drain /pack
Beets Leave root ends on: cut off tops leaving 3 cm (1 1/4 inch stems. Cook in boiling water until tender. Cool. Peel and slice or dice. None Pack
Broccoli* Remove woody stems and trim. Cut into florets not more than 3 cm (1 1/4 inch) across
Medium – 3
Large – 4
Brussels Sprouts* Trim stems and outer leaves.
Small – 3
Medium – 4
Large – 5
Cabbage Trim outer leaves and core. Cut in wedges or shred coarsely. Wedges – 2 Shredded -1 Chill/drain/ pack
Carrots Remove tops and scrape or peel. Leave small carrots whole.Slice in 1 cm (1/2 inch) disks, dice or cut lengthwise in fingers. Cut – 3
Whole – 5 Chill/drain/ pack
Cauliflower* Break head into small florets about 3 cm (1 1/4 inch) in diameter. 3 Chill/drain/ pack
Remove husks and silk.
Cut kernels from cob.
Remove husks, trim cobs to even lengths.
S – 7
M – 9
L – 11
Chill & pack
Fiddleheads Leave whole. Freeze on tray after blanching and before packing. 2 Chill & drain
Herbs 1/(basil, dill, marjoram, mint, parsley, rosemary, sage, savory, tarragon) Chop. None Freeze on tray before packing
500 mL (2 cups) in 30 mL (2 tbsp) butter 4 minutes None Drain & 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 (3/4 inch) fingers or 1 cm (1/2 inch) slices Fingers – 1
Slices – 1 Chill/drain/ pack
Remove stem & blossom. Leave whole
Pods keep 5 – 6 months.
Peppers, green or red Leave whole or remove seeds and stems, cut in half or chop. Freeze chopped pepper before packing None Pack or freeze and pack.
Pumpkin Cut/break apart, remove seed/fibers. Cut in chunks; steam, boil or bake until tender. Cool and scoop from rind. Mash or sieve. None Pack
Spinach, Swiss chard Wash thoroughly. Cut in 3 cm (1-1/4 inch) pieces or separate leafy parts from stalks and cut stalks in 10 cm (4 inch) lengths 2 Chill/drain/ pack
Marrow/Zucchini Cut in 1 cm (1/2 inch) slices 2 Chill & drain. Freeze on tray before packing
Cut in serving-size pieces/steam until tender OR cut in chunks, steam/boil/bake, cool, scoop from rind & mash.
Peel & dice OR Cook & mash.
Cook & mash.
2 minutes None
Tomato Peel, quarter, add 5 mL (1 tsp) salt, dash pepper & 5 mL (1 tsp) sugar to 1 kg (2 lb) tomatoes; cook until tender, 5 – 6 minutes None Pack
Turnip Peel, dice & boil until tender; mash Or Peel, dice & blanch None
2 minutes Pack
*To remove insects that may be present in broccoli, Brussels sprouts or cauliflower, before blanching immerse prepared vegetable for 15 minutes in 1 L (4 cups) water and 25 mL (2 tbsp) salt. Rinse thoroughly.
Sources: The Microwave Guide and Cookbook and Freezing Foods (Agriculture Canada, 1978)
Select firm, ripe, top quality fresh fruit for freezing; freezing will not improve the quality.
Keep everything clean. Freezing doesn’t kill bacteria or germs, it only inactivates them.
Wash fruit quickly in cool water, do not soak.
Pack fruit in small quantities and handle the fruit as little as possible.
Blueberries, saskatoons, cranberries, currants, gooseberries, and rhubarb may be frozen without sugar or syrup. Pack them in measured quantities for use in recipes.
Berries can be frozen individually by washing, draining and placing in single layer on paper towels to remove remaining moisture. Place in single layer on a rimmed cookie sheet, freeze. Transfer to freezer bag, seal and label.
Use freezer bags or rigid plastic containers. Plastic food tubs and milk cartons may be recycled. Wash in hot sudsy water and rinse well. Rinse in hot water before using.
Label and date each package with name of product and added ingredients (e.g. Sugar)
Store fruit 8-12 months at -18(C (0(C).
Thaw fruit in the refrigerator; use when just thawed.
Sugar is not needed to preserve fruit by freezing, but sugar does give thawed fruit a better texture and flavour. Fruit may be frozen in a syrup, sugar or unsweetened pack. Berries and rhubarb may be packed without sugar or syrup for later use in desserts, jams and jellies or restricted diets. Recipe-sized quantities of fruit and sugar may be packed for later use, too. Label each package with amount of ingredients.
Discolourationg of Fruit
Fruits that discolour easily during handling and freezing, such as peaches, pears, apples and apricots, will need to be dipped in a solution that prevents discolouration. During handling of large quantities of fruit, use a solution of 75 mL (1/3 cup) lemon juice to 1 L (4 cups) of water. Browning of fruit caused by enzyme activity during freezer storage may be slowed down by the addition of salt, sugar, and acid such as lemon juice or a commercial anti-darkening agent.
Dry Sugar Pack
Sprinkle sugar over fruit; mix gently until the juice is drawn out and the sugar is dissolved. Pack into containers. Freeze immediately.
Dry Sugar Pack with Ascorbic Acid
For 1 L (4 cups) of prepared fruit, use 1 mL (1/4 tsp) powdered or crystalline ascorbic acid. Dissolve in 50 mL (1/4 cup) cold water, sprinkle over fruit and mix. Add sugar and mix again.
Designation Sugar Water Yield
Thin 250 mL (1 cup) 500 mL (2 cups) 650 mL (2-1/2 cups)
Moderately Thin 250 mL (1 cup) 400 mL (1-2/3 cups) 550 mL (2 cups)
Medium 250 mL (1 cup) 250 mL (1 cup) 375 mL (1-1/2 cups)
Heavy 250 mL (1 cup) 200 mL (3/4 cup) 325 mL (1-1/4 cups)
Allow 175 mL (3/4 cup) syrup for each 500 mL (2 cup) container. Use the strength of syrup best suited to the tartness of the specific fruit according to personal taste. Slice or cut fruit directly into containers. Cover with syrup and leave headspace for expansion. Crumple a piece of non-absorbent paper and place it on top of the fruit to keep the fruit submerged in the syrup. Cover and freeze.
Syrup Pack with Ascorbic Acid
To 1 L (4 cups) cold syrup, add 1 mL (1/4 tsp) powdered or crystalline ascorbic acid. Follow manufacturer’s directions if using a commercial product.
Freezer Strawberry Jam
500 mL crushed strawberries (1 L (quart) whole) 2 cups
1L granulated sugar 4 cups
175 mL water 3/4 cup
57 g package fruit pectin crystals 2 oz.
Scald freezer containers and lids with boiling water. Thoroughly crush berries, one layer at a time. Measure 500 mL (2 cups) into a large bowl. Stir in sugar, mix well and allow to stand 10 minutes. Mix water and pectin in small saucepan, bring to a boil and boil 1 min. stirring constantly. Remove from heat and stir into fruit mixture. Continue stirring 3 minutes.
Pour into sanitized freezer containers. Leave 1cm (1/2 in.) headspace. Cover at once with sanitized lids. Let stand at room temperature until set (up to 24 hours). Label and date. Store in freezer up to one year or in refrigerator for up to 3 weeks.
By Betty Burwell, Home Economist
Source: Information in this section was collected by Betty Burwell while operating the Food Pro Line for Food Focus Saskatoon, Inc.