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 food preservation season arrives. The food preservation questions fly into Extension 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 use 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.  Whether you do the work yourself or someone gives you a jar, don’t be shy about asking questions. Compare old recipes to the research-tested current ones; if they match, go ahead and use the “old one.”

Food canned improperly at home can be deadly.

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.

Don’t set them out in the hot summer sun to seal, either.

If you are surfing the internet 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. Use the proper equipment, too.

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 website at www.ag.ndsu.edu/food. If you forget the Web address, try the key words “NDSU Extension food preservation” on Google and you should find the site.

Salsa (for canning)

Yield: 13 pints

7 qt. paste tomatoes, peeled, cored and chopped
4 c. long green chili peppers, seeded and chopped (about 12 chilies)
5 c. onion, chopped (about 5 medium onions)
½ c. jalapeno peppers, seeded and finely chopped (about 2 peppers)
6 cloves garlic, minced
2 c. bottled lemon or lime juice
2 Tbsp. salt
½ Tbsp. red pepper
2 Tbsp. ground cumin
3 Tbsp. oregano leaves
2 Tbsp. fresh cilantro

Procedure:

Wash hands thoroughly before handling food. Prepare peppers as described previously. Wear rubber gloves while handling chili peppers or wash hands thoroughly with soap and water before touching your face.

Prepare tomatoes: Wash tomatoes. Dip in boiling water for 30 to 60 seconds or until skins split, then dip in cold water. Slip off skins and remove cores.

Combine all ingredients except cumin, oregano and cilantro in a large pot and bring to a boil, stirring frequently. Reduce heat and boil 10 minutes. Add herbs and spices and simmer for another 20 minutes, stirring occasionally. Ladle hot into hot pint jars, leaving ½-inch headspace. Wipe jar rims. Cap with properly pretreated lids. Adjust lids and process in a boiling water canner for 20 minutes.

Note: This recipe is best suited for paste tomatoes. Slicing tomatoes require a much longer cooking time to achieve a desirable consistency. You may decrease the amounts of spices, but increasing the amount is not advised. You may make adjustments to suit your tastes after opening the jars.

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