UMaine Extension Offers Canning Recommendations
Contact: Beth Calder, 207-581-2791
ORONO, ME–University of Maine Cooperative Extension is advising Mainers to get up-to-date information before canning their garden harvest. Botulism can occur when safe canning methods are not used, because botulism-producing bacteria thrive under the low-oxygen conditions found in canned foods, and at food pH levels above 4.6. UMaine Extension county offices can provide current canning information.
Rising food costs have inspired many Mainers to plant new or expanded gardens this year with an eye to preserving their harvest. Yet many people may not know that vegetables that are not pickled (including pumpkin and squash)–as well as meat, poultry, fish, and seafood–must be canned using a pressure canner, because these foods have a low acid content. This is why canning salsa has been a hot topic this year: some tomatoes do not have enough acidity to make a safe canned salsa. The National Center for Home Food Preservation recommends adding two tablespoons of bottled lemon juice or a half teaspoon of citric acid per quart of whole, crushed or juiced tomatoes before water-bath canning.
Match the canner to the food
There are two types of home canning methods: boiling-water-bath canners and pressure canners. The type of canner that you use should be based upon the type of food you are preserving. According to UMaine Food ScienceSpecialist Beth Calder, fruits, pickled foods, sauerkraut, marmalades, fruit spreads, jams, jellies, fruit butters (except for pumpkin) and salsa can be safely preserved using the water-bath canning method. “However, make sure you use a scientifically tested recipe from a reputable resource,” she says.
All other foods should be preserved using a pressure canner. This is because botulism-producing bacteria produce spores that can survive boiling water temperatures, but are destroyed using a pressure canner with the appropriate time and pressure, which reaches temperatures between 240 and 250 degrees F.
Dial-type pressure gauges should be checked annually for accuracy. Extension offices are equipped to test some gagues. In other case, consumers can contact National Presto Industries, Inc. to have dial gagues tests (this process can take up to two weeks.) Call 800-368-2194, e-mail contact@gopresto.com, or write to Test Kitchen, National Presto Industries, Inc., 3925 North Hastings Way, Eau Claire,Wisconsin 54703-3703.
Use the right types of jars and seals
Only glass mason-type jars with self-sealing lids and screw bands should be used. Avoid older glass canning jars with the wire bales and rubber rings. Also, the use of paraffin wax in jam or jelly products does not ensure a proper seal and is no longer recommended.
Resources for home canning
UMaine Extension publishes the Let