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Published September 10, 2010, 12:00 AM

Preservation methods have been updated

“I found my great-grandma’s canned green bean recipe. It says to process them in a water-bath canner. Is it safe to use?”

By: Julie Garden-Robinson, INFORUM

“I found my great-grandma’s canned green bean recipe. It says to process them in a water-bath canner. Is it safe to use?”

“I bought some one-piece zinc reusable canning lids at a garage sale. Can I use them as covers on my home-canned food?”

“I don’t know why my jars of salsa didn’t seal. I really tightened them. Should I tighten them more next time?”

“Someone said I could can food in my oven. Is that safe?”

I can always tell when August and September arrive. The food preservation questions fly into Extension Service offices state- and nationwide.

By the way, the answers to the opening questions are all no, but some need a bit more explanation as to why.

Canned food recipes in great-grandma’s handwriting are nice to have, but you might want to frame them as mementoes instead of using them. Since the early days of home canning, the equipment has changed and advances have been made in the processing methods.

Some old food preservation methods stand the test of time, but most have been modified to be safer.

Low-acid foods, such as green beans and other vegetables, meats and many mixtures of foods, must be canned in a pressure canner to ensure safety. A pressure canner allows the temperature to reach a high enough level to kill bacterial spores, which could produce a toxin if the spores are not inactivated.

Unless you process home-canned foods following current recommended methods and use tested recipes, you could put yourself at risk for botulism, a potentially fatal form of foodborne illness.

Using proper equipment ensures a safe, high-quality product, too. The U.S. Department of Agriculture recommends using two-piece lids and buying only the quantity of lids that you will use in a year.

Don’t use your muscles when tightening canning jars. The lids should be finger-tip tight. Be sure to read and follow the manufacturer’s directions. After the jars of food have cooled, remove the screw bands. Otherwise, the lids can rust onto the jar. You can reuse the screw bands but not the lids.

You may hear about innovative uses of your appliances to can food. Food safety experts do not recommend that you can food in your oven, microwave or dishwasher.

If you are surfing the Web for food preservation information, you may encounter some “interesting” canned food recipes along the way. Be sure to go to reputable sites that provide research-tested recipes.

You can learn more about canning equipment and processing acidic and low-acid foods, pickling, making jelly, sauerkraut and freezing a wide variety of foods at the NDSU Extension Service website at If you forget the Web address, try the key words “NDSU Extension food preservation” on Google and you should find the site, too.

Here’s a recipe from the University of Georgia Cooperative Extension Service.

Preserves are small pieces of fruit in a clear, gelled syrup. Apple preserves served with warm home-baked bread or muffins brighten an autumn day.

Apple Preserves

6 cups peeled, cored, sliced apples

1 cup water

1 Tbsp. lemon juice

1 package powdered pectin

½ lemon, peeled and thinly sliced (optional)

4 cups sugar

2 tsp. nutmeg

Wash half-pint canning jars with hot, soapy water and rinse. Sterilize the jars by boiling them in water for 10 minutes and keep the jars in hot water until filled. Prepare jar lids according to the manufacturer’s directions. Combine water and lemon juice in a pan. Quickly peel, core and slice apples and add to water-lemon juice mixture (to avoid excessive browning). Simmer (covered) for 10 minutes. Stir in pectin and bring to a full rolling boil. Add lemon slices (optional) and sugar. Return to a boil. Boil hard one minute, stirring frequently. Remove from heat and add nutmeg. Carefully pour hot preserves into hot jars, leaving

1/4 inch of headspace. Wipe jar rims and adjust lids. Process for five minutes in a boiling-water bath. Carefully remove the jars from the boiling-water bath and allow to stand undisturbed (out of air drafts) for at least 12 hours.

Makes six half-pint jars. Each jar has about eight servings, with 70 calories, 0 grams (g) of fat and 19 g of carbohydrate per serving.

Julie Garden-Robinson, Ph.D., L.R.D., is a North Dakota State University Extension Service food and nutrition specialist and associate professor in the Department of Health, Nutrition and Exercise Sciences.