Eons and eons before there were canning kettles and jars there was ice. Big ice, which came in the form of glaciers. Folks figured out that placing their freshly caught game in the vicinity of the stuff helped prolong the quality of their precious cache.
And thus, a valuable food preservation technique was born.
Now, freezing is not the most glamorous aspect of preserving. You don’t end up with a sparkling row of fancy preserves in your pantry to impress family and friends. But freezing does get the job done in a fairly tidy and effortless manner. When you have extra produce and no time to turn it into jam or pie, for instance, pop it into the freezer until life has slowed down a bit.
If you really want to take advantage of that big ol’ cold zone this season, you may want to latch on to a book that has at least a chapter on the subject. You can also download some great information from the online catalogs of Oregon State University (extension.oregonstate.edu/catalog/).
In the meantime, here are a few of the basics to consider:
Start with quality. Freezing maintains quality (to a point), but it can’t improve it, so start with really great and fresh food. Then, prepare it under sanitary conditions and store it at 0 degrees F. or below.
Fast freezing is best. As food freezes, the water inside it forms ice crystals. The faster the freezing occurs, the smaller the ice crystals. Slower freezing allows large crystals to form, which tend to puncture cell walls. When that occurs, more of the foods natural juices will run out of the food during thawing, which undermines quality.
A little texture change is to be expected, but you can control the destruction to a certain degree. To ensure quick freezing, turn the freezer to its coldest setting the day before freezing a significant amount of food; then place foods in a single layer in the coldest part of the freezer until frozen. Once your batch of food is frozen, you can return the freezer setting to 0 degrees F.
Juicy isn’t better: The higher the water content of the food, the lower the quality after thawing. Changes in texture after thawing are most noticeable in fruits and vegetables with a high water content; all that extra water forms more ice crystals. Tomatoes, for example, will become mushy if frozen in the raw state. If you cook the tomatoes into tomato sauce before freezing, however, you’ll cook off a lot of that moisture.
Control those enzymes. One visualizes a frozen chunk of food as a fairly inanimate object. But freezing doesn’t completely inactivate those enzymes. Enzymes are what cause fruits and vegetables to go from beautiful and fresh to brown and yucky, and while freezing slows down their efforts, it doesn’t completely stop them. And so, they must be inactivated before the food is pitched into the freezer. In the case of vegetables, inactivation can be achieved by a heat treatment known as blanching. Typically, this means immersing the vegetable in boiling water for a minute or so. But you can also blanch vegetables in steam or the microwave oven.
With fruits, only the light-colored ones (such as apples, pears, peaches, and nectarines) need extra attention so that the enzymes don’t wreak havoc on their beautiful color. The addition of an antioxidant agent (such as ascorbic acid), and sugar do the trick. On the other hand, if you don’t mind a little discoloration, you can skip the treatment.
Another way to deactivate the enzymes in vegetables is to roast them. This truly is my favorite method for freezing batches of vegetables from my garden. Simply toss them into a roasting pan, along with a splash of olive oil, some garlic, a little salt and pepper, and perhaps some onions and herbs. Roast until golden and richly flavored. Let cool, then pack into freezer bags and freeze.
Correct packaging is essential. Freezer burn, the brownish or whitish areas that appear dry, tough and grainy, is what you get when foods aren’t properly packaged and evaporation of moisture from the surface occurs. The food is safe to eat, but the appearance isn’t as appealing and flavor may be affected. To prevent it, seal foods snugly in moisture and vaporproof materials that are specifically designed for use in the freezer.
Don’t forget the head space. Remember, food expands when frozen, so you need to leave an appropriate amount of room for that to occur or your packaging will burst. The exception is when packing unsweetened fruit that is already frozen in individual pieces. If you’re using a sugar, juice, water or syrup pack, however, leave 1/2-inch head space for plastic freezer bags or pint containers, 1 inch for quarts. Do not freeze fruits with liquid in standard glass canning jars (they’re more likely to burst, even with adequate head space).
Sugar and syrup packs: Juicy fruits and fruit for pies can be packed in sugar or a sugar syrup.
To pack in sugar, for every 2 to 3 pounds of fruit, mix with 1 cup of sugar, gently until the sugar has dissolved in the juice.
Fruits that are served uncooked can be frozen in syrup made from either cane or beet sugar.
For a light syrup, use 1 cup of sugar to 4 cups of water; for medium syrup, 1 3/4 cups sugar to 4 cups of water and heavy, 2 3/4 cups of sugar to 4 cups of water. Dissolve the sugar in cold or hot water, allowing to cool before adding to fruit. Use 2/3 cup of syrup for each pint of fruit.
Basic directions:Wash the vegetables thoroughly and trim as you would for cooking. Blanch in a large pot (with a tight-fitting lid) filled with water that has come to a rolling boil. Allow 1 gallon of water for each pound of vegetables. Cover the pot and begin counting time as soon as vegetables are placed in the boiling water. Remove from the boiling water using a large slotted spoon and chill immediately in ice water. When thoroughly cool, drain and proceed with packing the vegetables in containers for the freezer.
I prefer to lay the blanched and drained vegetables out in a single layer in the freezer and freeze until firm, then pack the individually quick frozen vegetables in storage containers and return to freezer. This way you are dealing with individual pieces of vegetable rather than solid blocks.
Store them at 0 degrees F or below. Most fruits and vegetables maintain high quality for 8 to 12 months. Longer storage in the freezer won’t make them unsafe to eat, but the quality won’t be as good.
Vegetable blanching time:
Asparagus: small stalks 1-1/2 minutes, medium stalks 2 minutes, large stalks 3 minutes.
Beans: 3 minutes.
Beets: Cook until tender before freezing (small, 25 to 30 minutes; medium, 45 to 50 minutes)
Broccoli: (cut through stalks lengthwise, leaving heads 1 inch in diameter) 3 minutes.
Carrots: (dice or slice) 2 minutes.
Cauliflower: (split heads into 1-inch sized pieces) 3 minutes.
Corn: (cut or on the cob) 4 to 5 minutes.
Herbs (fresh): No blanching necessary; simply wash, drain, pat dry with paper towels then wrap in freezer wrap and place in freezer bag.
Onions: (chop or slice) May be frozen unblanched (my prefered method is to saute before or roast in olive oil before freezing).
Peas (edible pod): 1 minute.
Peas (shelled): 1 1/2 minutes.
Peppers (sweet): May be frozen unblanched (my prefered method is to saute before or roast in olive oil before freezing).
Peppers (hot): May be frozen unblanched. Broil to remove skins (make small slit to allow steam to escape); freeze whole or remove stems and seeds first.
Potatoes: (peel, remove deep eyes, bruises, and green surface coloring; cut into 1/4- to 1/2-inch cubes) 5 minutes.
Potatoes (french fries): (peel, remove deep eyes, bruises, and green surface coloring; cut into thin strips) fry in deep fat until light brown. To serve, bake at 400 degrees F for 10 to 20 minutes.
Spinach (and other leafy greens): (remove tough stems and wash thoroughly) 1-1/2 to 2 minutes (depending on age of the greens).
Summer squash (including zucchini): Slice 1/4-inch thick, 3 minutes; 1-1/2-inch thick, 6 minutes.
Tomatoes: I prefer to roast tomatoes in olive oil or prepare as a sauce or puree before freezing.
Freeze now, jam later
If you want to make jam, but don’t have the time to make and process jars of jam, freeze the fruit until you’re ready.
Here are a few tips:
For traditional jam recipes (without added pectin) in which you combine and cook sugar and fruit, go ahead and prepare the fruit as directed and combine with the sugar (and lemon juice if its called for) before freezing. Store in air-tight freezer containers or plastic pouches, clearly dated, contents (1 batch of jam, with sugar and whatever else is called for in the recipe), and what you need to do with the stuff once it’s thawed to turn it into jam. Store the uncooked mixture in air-tight freezer containers or resealable plastic freezer bags and toss them in the freezer for up to 12 months. Down the road, when you’re ready to make the jam, simply thaw the pre-measured fruit and sugar mixture and proceed with the cooking and processing steps.
For recipes using liquid pectin (it comes packed in pouches), you can also combine the measured amount of sugar and fruit, then store the uncooked mixture in air-tight freezer containers or resealable plastic freezer bags in your freezer for up to 12 months. Down the road, when you’re ready to cook the jam, simply thaw the fruit and sugar mixture and proceed with the cooking and processing steps as indicated in your recipe.
For recipes using powdered pectin, you cannot combine the sugar with the fruit before freezing. Just freeze the prepared and measured fruit. Remember, since freezing alters the volume of fruit (it expands when frozen, and collapses when thawed), be sure and pre-measure each batch and indicate the amount on the package. Months from now, when you’re ready to make your jam, simply thaw the fruit and proceed with your recipe, adding the correct amount of sugar and powdered pectin as indicated. Of course, if you have a kitchen scale, you can weigh out the appropriate amount of frozen fruit when the time comes to make jam.
Exquisite strawberry jam
Makes 4 half-pints.
This is my favorite strawberry jam recipe and can be frozen or put up in jars. It’s free of commercial pectin. The resulting preserves are what I would describe as a “soft” gel. But it’s a luscious preserve, no commercial pectin giving the jam an unnatural firmness, and full of fresh strawberry flavor.
Store it in your pantry, the refrigerator, or freezer.
The secret to perfection is the relatively brief, fast cooking in small batches (this recipe cannot be doubled). A wide, shallow pan (a 12-inch cast-iron skillet is perfect) is essential.
4 heaping cups washed and hulled strawberries (1 pound, 6 ounces; to ensure a high pectin content, about 1/4 of the berries should be slightly under-ripe)
3 1/2 cups sugar
1/3 cup strained fresh lemon juice
1 teaspoon butter (to control foaming during cooking)
Coarsely chop the berries by placing small batches of them into the work bowl of a food processor and hitting the “pulse” button several times (you can also do this by hand, of course, but it goes pretty slow). You should have 3 1/2 cups of coarsely chopped berries.
In a large bowl, combine the berries with the sugar and lemon juice. Gently stir the mixture using a rubber spatula until the sugar is evenly distributed and the juices have begun to flow; let the mixture stand, stirring gently every 20 minutes or so, for at least 1 hour, but no longer than 2 hours.
Wash 4 half-pint jars. Keep hot until needed. Prepare lids as manufacturer directs.
Scrape the mixture into a 12-inch skillet or saute pan. Add the 1 teaspoon of butter (this controls the production of foam). Bring mixture to a boil over medium high heat, stirring constantly with a straight-ended wooden or nylon spatula. Adjust the heat downward to keep it from boiling over, and boil for 7 minutes. Remove from heat.
Remove the skillet from the burner and let the jam settle for about 20 seconds; if any foam remains, skim it off. Ladle hot preserves into 1 hot jar at a time, leaving 1/4-inch head space. Wipe jar rim with a clean, damp cloth. Attach lid. Fill and close remaining jars.
At this point, the jam may be stored in the refrigerator or freezer for up to six months or longer without the quality suffering.
For long-term storage at room temperature, you will need to process the jars in a boiling-water canner for 10 minutes (at 1,000 to 3,000 feet, process for 15 minutes; 3,000 to 6,000 feet, for 20 minutes; above 6,000 feet, for 25 minutes). Using a jar lifter, remove the processed jars from the boiling water and let cool on the counter, undisturbed, overnight.
To freeze the ingredients now to prepare later:
Measure out the ingredients and store in a well-marked freezer container (date, ingredients, cooking directions)
Place in the freezer for up to 12 months.
When ready to make jam, thaw and proceed with cooking the jam.
Note about the consistency of the jam: This is going to be a “loose” jam, the kind that moves around in the jar slightly as its tilted. So if you don’t like such a soft gel, you might as well steer clear of this recipe. There’s also a stronger likelihood of fruit floating toward the top of the jar, which creates a clear layer of jam at the bottom of the jar. Here’s how I’ve managed to repair that phenomenon when it appears to be happening: About 3 hours after the jars have been removed from the boiling water canner, if you notice that the clear space at the bottom of the jars hasn’t started to fill in with fruit, then you can begin a cycle of turning the jars on their heads for periods of 60 minutes at a time (gently flip the jars for 60 minutes, then gently flip them back onto their bottoms for 60 minutes; repeat several times during the day or night). This really does seem to work.
Jan’s frozen strawberry daiquiri mix
Makes about 1 quart frozen strawberry puree
There are no special canning skills required to make up batches of this fresh strawberry puree. Just plenty of fresh local strawberries and a little bit of freezer space. This simple puree makes for heavenly rum-laden daiquiri drinks or alcohol-free strawberry-flavored treats all year long.
2 cups granulated sugar
1/3 cup fresh lime juice (from 2 medium limes)
1/4 cup water
1 quart fresh strawberries, washed and hulled
Combine the sugar, lime juice and water. Stir to mix, and then let stand until sugar is almost completely dissolved, about 15 minutes (mixture will be thick).
In blender jar or food processor, combine the sugar mixture with the berries. Blend until smooth. Pour into half-pint, pint- , or quart-size freezer containers. Alternatively, pour the mixture into ice cube trays and freeze until firm, unmold and pack into zip-lock freezer bags.
The mixture will become solid, but will have the consistency of a very firm sherbet, so you’ll be able to scoop portions from the main batch, then re-seal the mixture and store back in the freezer. Likewise, if you’ve frozen the mixture in ice cube trays, the cubes will not be rock-solid, but they will hold their shape when popped from the trays into storage bags.
For one strawberry daiquiri: In a blender jar, combine 3 to 4 tablespoons rum, 1/4 cup frozen strawberry daiquiri mix (2 average-sized cubes that have been frozen in ice cube trays) and 7 or 8 average sized ice cubes. Blend until smooth. Most blender jars can handle up to 4 servings.
The frozen puree makes a delicious non-alcoholic cooler when blended with a bit of sparkling water or soda and ice. Or for a more creamy “Smoothie,” blend in milk, a banana or yogurt or vanilla ice cream.
Rhubarb and orange butter
3 pounds rhubarb, cut into chunks
Grated rind and juice of 4 oranges
3 cups granulated sugar
Place the rhubarb in a large saucepan with the orange rind and juice. Cover pan and simmer gently for about 15 minutes, or until rhubarb is soft. Remove from the heat and beat well to puree. Add the sugar and stir until it dissolves. Continue cooking and stirring frequently, until thick and creamy.
For shelf storage: While the rhubarb butter is cooking, wash 7 half-pint jars. Keep hot until needed. Prepare lids as manufacturer directs. Ladle hot rhubarb butter into 1 hot jar at a time, leaving 1/4-inch head space. Wipe jar rim with a clean, damp cloth. Attach lid. Fill and close remaining jars. Process in a boiling water canner for 10 minutes. Processed mixture will keep, sealed, up to 1 year.
For Freezer or refrigerator: Ladle the cooked rhubarb butter into freezer jars or freezer containers, leaving 1/2-inch head space; apply lids. Let stand for 12 to 24 hours at room temperature; freeze or refrigerate. Will store in refrigerator for 1 month; in the freezer, up to 1 year.
Jan Roberts-Dominguez is a Corvallis, Oregon, food writer, artist and author of “Oregon Hazelnut Country, the Food, the Drink, the Spirit,” and four other cookbooks. Readers can contact her by email at firstname.lastname@example.org, or obtain additional recipes and food tips on her blog at www.janrd.com.