Canning Fruits and Vegetables

Canning methods have changed dramatically in recent years. Read our article including canning instructions for canning fruits and vegetables. Learn how to safely preserve your harvest.

by Sue Weaver

How to safely can and preserve fruits and vegetables at homeIs it safe to eat canned fruits and vegetables? And is canning fruits and vegetables something worth learning to do? In a word: yes.

However, there is more to preserving safe, tasty, nutritious canned fruits, vegetables and meats than hauling out Grandma’s old pressure canner.

Here are the facts about canning instructions and methods.

Because modern hybrid vegetable and fruit varieties are often less acidic than heirloom varieties and modern canned goods are generally stored under vastly different conditions than they were just decades ago, in 1989 our U.S. Department of Agriculture updated its home canning guidelines and declared certain old-fashioned canning methods verboten.

Extension Services in every state reprinted canning instruction manuals to reflect the USDA’s findings. In 1994 it released its own definitive work, Complete Guide to Home Canning.

Unfortunately, many home canners aren’t aware of these safety updates and still follow instructions from old books and bulletins. Others contend “the old ways are best.”

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Hobby FarmsBetween October 24, 2000, and January 10, 2001, the Center for Home Food Preservation in conjunction with the University of Georgia called 5,259 randomly selected households across the United States; 1,244 households reported freezing or home canning in 1999.

The Center polled 501 of these home-canning households with these startling results:

  • Only 19 percent followed canning instructions gleaned from cookbooks and County Extension bulletins (and some of these were badly outdated); 48 percent obtained instructions solely from friends or relatives.

To preserve high-acid products such as fruits, pickles and tomatoes, the USDA recommends water bath or pressure-canning methods.

Old-style, open-kettle canning as well as oven and microwave procedures are deemed unsafe.

Yet, 21 percent chose the open-kettle method and four percent canned in ovens. Only 58 percent of the home canners polled used the water-bath method and 15.5 percent used a pressure canner.

Furthermore, when canning low-acid foods like vegetables, poultry, seafood, meats and combinations such as stews and salsa, processing in a pressure canner is the only way to safely kill botulism spores.

Still, only 30 percent of the canners polled always used a pressure canner; 39 percent used water-bath canners, 29 percent used pressure cookers, 15 percent used the open-kettle method and three percent used the oven. Obviously, things need to change.

Safety and Benefits
Be sure to follow canning instructions exactly for your and others safety. A safely canned food yields numerous benefits.

Clostridium botulinum, the deadly neurotoxin that causes botulism, thrives in under-processed, low-acid, home-canned goods.

A single nibble or sip of botulism-laced food, ingested as soon as three or four days after processing, can prove fatal. Why take that risk? C. botulinum and the other bacteria that contribute to spoilage are easily destroyed when cooked for the right amount of time at 240 to 250 degrees F—the temperature in a properly-regulated pressure canner.

Canned foods are often more wholesome than weeks-old “fresh” produce at the market.

Even refrigerated, the nutrient content of fruits and vegetables begins declining at harvest. Within a week, up to 50 percent of certain vitamins may be lost. However, although heat destroys one-third to one-half of Vitamins A and C, riboflavin and thiamin, once these items are canned, the process slows to five to 20 percent per year.

Canning is economical. The same equipment—including canning jars—can be used year after year. Only lids must be purchased new each canning season.

Canning lets you savor favorite foods all year, including out-of-season and homegrown, organic goodies. It’s convenient—precook and can dried beans for chili recipes or chicken to simmer with those dumplings.

It beats freezing: stored canned goods don’t spoil when the power goes off. Most frozen foods claim a one-year life expectancy. But with only slight decline in looks and flavor, canned items can last for two to three years or more.

What You Need to Get Started
If you’re convinced and want to try canning this year, here’s what you’ll need to get started:

  • Reliable canning instructions and recipes
    Check the copyright date on material you may already have on hand. If it’s dated before 1989, it’s best to discard it. Take heirloom and other favorite recipes to your County Extension for updating or compare them to modern recipes and based on those, add significantly to their processing times.

Reliable canning instruction and recipes are free and abundant. Pick up bulletins from your County Extension agent or download them from the Internet. Phone or e-mail canning-supply companies such as the Alltrista Corporation (makers of Ball and Kerr canning jars and lids), and ask for free brochures. Many offer inexpensive materials like Alltrista’s 120-page classic, The Ball Blue Book: Guide to Home Canning, Freezing & Dehydration; 32nd Edition, available directly from Alltrista (see “Resources” on page 90). If in doubt, pressure canning (according to modern USDA recommendations) is always your safest ploy.

  • Wholesome, properly handled food
    When possible, grow or pick your own fruits and vegetables. For optimal flavor, nutrition and appearance, can them within six to 12 hours of harvest. Choose fully ripe (but not over-ripe), bruise- and blemish-free produce.

Harvest, pick or buy only the amount you can process in two to three hours. Rinse and lightly scrub fruit and veggies but don’t soak them prior to canning.

  • Canner
    If you put up vegetables, including low-acid tomatoes, poultry, meat, seafood or processed entrees such as chili or stew, you’ll need a pressure canner. Grandma’s pressure canner, if she had one, was a heavy, bulky monster with thick walls and a cumbersome clamp-on lid. Redesigned in the 1970s, today’s models are sleek, thin-walled and lightweight, featuring replaceable gaskets, twist-on lids with automatic cover locks, one or more safety valves and dial or weighted pressure gauges.

Pressure canners range in size and price from Mirro, Presto and Maitre’s petite 4.2 models (they handle three-quart jars and list for around $45 but often sell for much less) to the enormous All-American 941 (19 quarts or 32 pints and close to $350), although the average pressure canner holds seven quarts or eight to nine pint jars in a single layer or 18 pints in two and retails for $100 to $150.

Used canners purchased at yard sales or on the Internet may or may not be bargains. Before buying one, make certain all parts are present and functioning. You can pick up replacement gaskets, dial gauges, counterweights and safety valves for modern canners at most hardware stores or order them from manufacturers and canning supply outlets, but parts for antiquated canners are all but extinct.

Dial-gauge models, like those built by Presto and All-American, accurately measure the appliance’s internal pressure and are preferred by many home canners. One drawback: gauges must be checked for accuracy before every canning season and again if dropped or mishandled.

Weighted-gauge canners, manufactured by Mirro and Maitre, feature a steam vent or petcock closed by a weight that jiggles and hisses two or three times per minute while the canner is suitably pressurized. Both incorporate rubber or rubber-like lid gaskets to form a tight seal. The gaskets in modern canners are permanently pre-lubed at the factory but those in older models should be periodically slathered with vegetable oil. Nicked, gummy, stretched or dried gaskets don’t properly seal, causing steam leaks and under-processed canned goods. Replace them.

Never force-cool any pressure canner. Cool down is factored into processing time. Dousing any canner with running water causes lid-seal failures and liquid loss from jars. Older models’ lids can warp, resulting in unfixable steam leaks.

Because water boils at lower temperatures as altitude increases, and canning instructions are generally calculated for elevations below 1,000 feet above sea level, unless their gauges are adjusted, temperatures inside pressure canners used at higher elevations will be incorrect. Unsure if you’re affected? Ask your nearest County Extension agent for assistance. Don’t omit this step.

While you can put up fruit, high-acid or acidified tomatoes, relishes, pickles, jams and jellies in a pressure canner with the lid clamped in place and the exhaust valve (petcock) open, the same foods can be processed faster in a water-bath canner. You may want to buy both kinds.

Water-bath canners, sometimes called boiling-water canners, are deep, porcelain-covered steel or aluminum pots fitted with snug-fitting lids and removable canning racks. They cost $10 to $30 at hardware stores or the large discount chain stores. With canning racks removed, they can be used to fix hefty batches of food for group feeds or for freezing. In water-bath canning, packed jars are immersed in at least one inch of boiling water for an allotted time—nothing could be simpler!

  • Canning jars
    Buy them new, packed one dozen per package, at grocery stores, hardware stores and the like, in 1¼2 pint, pint, 1 1¼2 pint, quart and 1¼2-gallon sizes, and in standard and wide-mouth configurations. Most popular are pints and quarts, with canners designed to contain these sizes. Wide-mouth jars, measuring three inches across, are easier to fill, empty and wash than their standard (2 3¼8”) mouth cousins.Jars are safe to reuse if they’re designed for use with modern, flat canning lids and screw-on rings. Scaly, film-covered jars are salvageable. Soak them for two to three hours in one cup of five percent acidity vinegar to one gallon of water solution, then hand or machine wash as usual. When considering a box of used canning jars, glaze your forefinger around their rims, checking for chips, nicks and the sort of uneven surface that will prevent your canning lids sealing. With use, jars do weaken and crack. New ones are often a better buy.

Don’t buy or save commercial mayonnaise containers to use as canning jars. They’re neither heat-tempered nor sturdy enough to withstand home canning, especially more than once. A mayonnaise jar’s narrower rim surface makes seal failure likely and it could shatter during processing or even explode when the canner is opened. If you must use recycled food containers, use them only for water-bath canning, never inside a pressure canner.

  • Canning lids
    Not so many years ago, canning jars were sealed with porcelain-lined, zinc screw-on lids with separate “jar rubber” gaskets. Antique jars are still around but finding new rubber gaskets is iffy and the USDA no longer endorses their use. The same goes for old-fashioned jars with wire-bail-attached glass lids and jar rubber seals.

The only safe canning topper is today’s self-sealing, two-piece vacuum lid. Its flat metal lid has a strip of rubbery gasket compound molded to its crimped underside. Heated, the compound softens and semi-seals while still allowing air to escape from the jar. This seal becomes airtight as the finished product cools and a vacuum forms.

During processing, the lid is clamped in place by a metal screw-on band or ring, which is removed after the finished product cools. Lid flats must never be reused but screw bands, if properly handled, will last indefinitely. Lids are sold as two-piece units or flats only.

Canning lids boast a five-year shelf life, although with age, more seal failures occur. It’s best to buy just enough for a single canning season. Over 30 companies manufacture these lids and not all work precisely the same. Always read and follow manufacturer’s instructions when prepping canning lids for use.

  • Accessories
    While most of the essentials you’ll need for processing food are standard kitchen tools, a few items are specific to canning.

Spooning food into canning jars is a lesson in frustration; wide-mouth plastic funnels make filling canning jars a breeze.

You’ll need a jar lifter—a specially-shaped set of tongs with rubber-coated handles—for fishing blistering hot jars out of your canner.

For cold-packing fruit, a small-bladed plastic or rubber spatula will coax bubbles out of jars before processing. Some instructions recommend a knife but metal causes certain fruits to turn odd hues.

To prevent breakage, you shouldn’t pack cool jars with
warm food. Bring them to a simmer in a kettle of water and hold them there till you’re ready to fill them. Use a large kettle that will hold all the jars for one batch. A water-bath canner is ideal.

An accurate kitchen timer is a must, as are measuring cups and spoons. Canning is an exacting science. Time and volume measurements must be precise.

Saucepans for warming lids; colanders for draining product; knives and cutting boards for peeling and chopping; pot holders or mitts to protect your hands; a big spoon for stirring and towels to cool your canned goods upon.

Home canning is a safe, economical way to put delicious, nutritious food on your table at every meal. Blackberry jam for breakfast, tasty home-canned chili for lunch, green beans from your garden, peaches from your trees—delicious! Give canning a try. Here are some more resources.

When that first batch of jewel-like jars stands cooling on your countertop, you’ll be thrilled you did.

This article first appeared in the Fall 2002 issue of Hobby Farms magazine. Pick up a copy at your local newsstand or tack and feed store.

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