Preserving the Harvest – canning, freezing and dehydrating foods

Kris Wetherbee

Canning, Freezing and Dehydrating

You did all the right things — prepared the soil, planted, watered and fertilized your way to the perfect garden filled with an assortment of fabulous foods. Only now the fruits of your labor are getting a little out of hand as bushels of ripened squash, tomatoes, cucumbers and apples impatiently wait to be picked, and picked, and picked …

That’s OK. In fact, that’s great, because now you can capture summertime flavor at its peak of perfection. Canning, freezing and dehydrating are three ways to preserve fresh fruits and vegetables and enjoy your garden surplus all winter. Plus, you may discover that you enjoy preserving your harvest as much as you do growing it. Though I do need to warn you — the flavor of home-grown and home-preserved produce is superior and can be quite addicting.


Ten years ago I started preserving the bounty from my own garden. Since I had bushels of extra tomatoes, canning was naturally my first choice. Back in those days I canned lots of tomato ketchup and soup, plus jar after jar of delicious salsas and my favorite pasta sauce. Soon I tried cucumbers, peppers, zucchini and strawberries, and I found that some things are even better when frozen or dried (dehydrated).

Zucchini turns to mush when canned as a vegetable unless it’s pickled or transformed into a tasty relish. Peppers somehow keep their magical crunch when diced and then quickly frozen (no blanching necessary) into convenient servings just right for a steaming pot of chili or sizzling stirfry. The ultimate though is a sugary sweet treat of dried Asian pears.

Knowing which variety you’re growing will also help you decide on which method of preserving to use. `Fern’ strawberries are excellent when frozen — not so for the newer variety `Seascape,’ which is better when preserved into jams and jellies. Some tomato varieties like `Sausage’ or `Viva Italia’ are better canned; others such as `Early Girl’ or `Principe Borghese’ are choice for drying. And though any Asian pear is delicious when dried, `Shin-Li’ with its spicy cinnamon flavor is in a class by itself.

Canning, freezing and drying your garden surplus also gives you lots of choices. If you don’t like frozen green beans, then can them instead with a nice sprig of fresh basil added to each jar. After all, it depends on what you and your family want or enjoy the most.


Canning preserves food by applying sustained high heat to destroy microorganisms that can cause foods to spoil. Once canned foods are cooled, a vacuum seal is formed, which prevents further spoilage.

Each year I process more than 300 jars of canned foods without a single case of food poisoning. (Although, I can’t say the same for several restaurants I’ve eaten at over the years.) The reason I’ve had such success with canning is that I always follow the rules. A good canning book or your local county extension agent (in the phone book under the Government section) can provide you with the proper canning information along with great recipes. That’s your first step.

The next step is to know which of the two processing methods you should use, and that depends on the acidity of the food. Acidic foods include fruits, jams, jellies, relishes, most tomatoes (increase the acidity of low-acid tomatoes with 2 tablespoons of lemon juice or 1/2 teaspoon of citric acid per quart of processed tomatoes) and anything pickled in a vinegar solution, such as sauerkraut or pickled vegetables. These foods are processed using a boiling-water canner (212 degrees).

Low-acid foods such as vegetables and meats are processed at a higher temperature (240 degrees), using a steam-pressure canner with either a weighted or dial gauge. If you’re a beginner, I recommend starting with something simple, like a strawberry jam using the boiling-water method.

Here are a few basics to get you started. Always use glass canning jars, sometimes called Mason jars, designed to withstand heat shock. These are available in either a narrow mouth (good for jams, sauces and soups), or a wide mouth, which makes it easier to process and to retrieve those pickles, peaches, green beans and whole tomatoes. For each jar, you’ll need the two-piece lid consisting of a new metal vacuum lid and used or new metal screw ring (band).

Any large pot that’s 4 inches higher than the lidded jars can be used as a boiling-water canner, but you’ll also need a wire rack to keep the jars away from direct heat. Commercial canners (wire rack included) made of porcelain-coated steel or aluminum are readily available and can usually be found for less than $20.

A steam-pressure canner is required if you’ll be canning low-acid foods. Other useful utensils for canning include a plastic or metal funnel for filling jars, a plastic heat-resistant spatula for removing air bubbles from jars, and a rubber-coated jar lifter to remove hot processed jars from the canner. Additional handy items include several large saucepots, a food mill or processor, a juicer (for making jellies) and a cooking timer.


Canned foods may store longer than frozen foods, but freezing is an excellent way to preserve the ultimate of freshness, flavor, texture and nutrients. And most frozen foods keep for up to a year. (Although we’re still enjoying delicious blueberries from the 1997 harvest!)

Unlike canning, freezing slows down enzyme activity and retards growth of microorganisms with extreme cold. The blanching process, where food is briefly cooked, also inactivates enzymes that can destroy the flavor of vegetables. Likewise, blanching prevents the breakdown in texture, flavor and color of vegetables.

To blanch, use 1 gallon of boiling water per 1 pound of vegetables. Put prepared vegetables in a metal strainer or wire basket, then lower into boiling water for the time indicated in the following preservation chart. Quickly remove vegetables and immediately immerse into ice water (to stop the cooking process) until cool, then pat or spin dry with a salad spinner. When processing large quantities for freezing, blanch vegetables in small amounts.

Fruits and vegetables do not need to be blanched before freezing as long as you plan to use them within four weeks time. However, vegetables you’re planning to keep frozen for more than four weeks should be blanched. The exceptions are green onions, tomatoes, hot peppers, herbs (except basil), sweet peppers cut into strips or chunks, and grated vegetables like zucchini and carrots.

Freezing works well for fruits, some vegetables and herbs. Berries and grapes are remarkably easy to do using the “tray freezing” method. Place some waxed paper on a cookie sheet and spread washed and drained berries in a single layer on the waxed paper. Put the cookie sheet in a freezer until the berries are firm, then slide the berries into freezer containers or snap and seal freezer bags. This way the berries are individually “flash frozen” so you can pour out the exact amount needed for delicious blackberry muffins or pie.

The key to successful freezing is to always use airtight containers. Otherwise, when ice crystals on the food’s surface are exposed to oxygen and evaporate, moisture is pulled out, resulting in freezer burn. The food may be safe to eat, though somewhat dried out and not as tasty. I like the convenience and flexibility of plastic freezer bags. Other options include rigid plastic freezer containers and dual-purpose glass canning jars designed for freezing.

For the best flavor and longest storage, keep frozen foods at 0 degrees Fahrenheit or lower. Choose young, tender vegetables for freezing — not overly mature ones (these are better canned). Also, for the best flavor, do not harvest produce until you are ready to freeze it. And here is a tip to prevent fruits like peaches, apricots, apples and pears from turning brown. Add lemon juice, ascorbic acid (Vitamin C) or honey to a syrup used for freezing fruit (wet pack method), or mix with water to use as a dip for raw fruit (dry pack method).


The oldest method of food preservation is also one of the most convenient. Since 80 to 95 percent of the moisture is removed, dehydrated foods take less storage space than frozen or canned foods. Flavors also become concentrated, so use your fresh, vine-ripened and mature produce for drying.

Sun drying is free, though not always readily available. Other factors such as heat, dry air and air circulation are also variable outdoors. That’s why a good dehydrator is well worth the investment — then these factors are easily controlled.

Just think of the possibilities. Cherries, grapes, Asian pears, apricots and apples make flavorful snacks. Celery leaves, onions and parsley season soups and stews. You can dehydrate corn and sweet peppers or even make your own fruit leather. Dehydrated tomatoes create a thick sauce in a snap, and thinly sliced and seasoned zucchini make tasty chips.


For maximum flavor and tenderness, process your fresh fruits and vegetables as soon as you harvest them. Slightly underripe vegetables are usually better for freezing, but overly ripe and mature produce should usually be thrown in the compost pile. There’s nothing more disappointing than to go through all the work of preserving foods that turn out too tough or mushy because they were overripe.

Be sure to have all your food and supplies ready before you begin. In fact, the whole process goes more smoothly when done in a rhythmic fashion, assembly line style. And if this is your first try at canning, gain from the experience of someone who knows what they’re doing and offer to assist them.

Use a permanent marking pen to label and date all your processed foods, and be sure to rotate them so you use the oldest ones first. Don’t preserve more than your family will use in a year, because come next season, you’ll want to start preserving all over again.


Here are the best methods for preserving these popular fruits and vegetables.


Food Canning Blanch Time Dehydrating

Apples yes yes yes

Berries yes, except yes no


Broccoli limited yes/4-5 min. no

Cabbage yes yes/4-5 min. no

Corn yes yes/(*) yes

Cucumbers yes no no

Grapes OK yes yes

Green beans yes yes/2-3 min. OK

Peas OK yes/2 min. OK

Pears, Asian/ yes yes yes


Peppers, limited yes yes


Peppers limited yes air dry only

Tomatoes yes yes yes

Zucchini limited yes yes

Food Comments

Apples Make applesauce, apple butter, pie

filling or dried snacks.

Berries Frozen berries give a fresher,

more flavorful taste to pie

fillings and muffins.

Broccoli These are great when combined with

other pickled vegetables.

Cabbage Limit canning to a pickled

vegetable medley or sauerkraut.

Corn (*) When freezing, blanch corn

kernels for 4 min., on the cob

for 2 min.

Cucumbers These are best used in picking


Grapes Freeze grapes whole, and use them

within 6 months.

Green beans Use only tender, stringless

varieties when drying.

Peas No need to blanch if you’ll be

using them within 4 weeks.

Pears, Asian/ Make a sauce from pears–it’s even

European tastier than applesauce.

Peppers, Use these only in canned pickled

Sweet products; no blanching needed when

diced or sliced before freezing.

Peppers For canning, peppers are best used

as a seasoning for pickles, beans,


Tomatoes Check with your local garden

center or seed catalog for the

best varieties for canning or


Zucchini Can as a relish or pickled; shred

first before freezing and skip


Kris Wetherbee is an organic grower of fruits, vegetables and herbs in Oakland, Oregon.3

COPYRIGHT 1999 KC Publishers, Inc.

COPYRIGHT 2000 Gale Group

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