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As we begin the annual canning season, many questions arise regarding home canned products. Here are a few common questions from readers and answers giving accurate information.
• How long will canned food keep? If properly sealed and stored in a cool, dry place, home canned food should keep for up to two years. However, for best quality, use within a year. Canned food stored in a warm place may lose some of its quality in a few weeks or months, depending on the temperature. Dampness may corrode metal lids, causing leakage and spoilage of the food.
• If canned foods are accidentally frozen during storage, are they safe to eat? Accidental freezing of canned foods does not cause spoilage unless the seal is damaged or the jar is broken. However, freezing and thawing may affect the taste and texture of the food. For best quality, store canned foods between 50 and 70 degrees. If jars must be stored where they might freeze, wrap them in newspapers, place them in heavy cartons and cover with more newspapers and blankets.
• Why do the undersides of metal lids sometimes discolor? Natural compounds in some foods, especially acids, may cause a dark deposit on the underside of jar lids. In sealed, properly processed canned foods, this deposit is harmless.
• If I find mold growing inside a jar of canned food, can I just scrape it off and eat the food? Mold growth in foods can decrease the acidity of the food. In home canned foods, this could mean that the acid level has become low enough to allow the growth of bacteria that cause botulism or other foodborne illnesses. Any home canned food (including jam and jelly) that shows signs of mold growth should be discarded.
• Do I need to process jams and jellies in a pressure canner or hot water bath – Is it okay to just ladle in the hot jam or jelly and pour hot paraffin on top and screw the two-piece lid tightly and let them naturally seal on the counter? No, paraffin cannot be used. All jams and jellies need to be processed in a hot water bath or pressure canner for the recommended length of processing time to insure the product seals safely.
• How can I tell if canned food has spoiled? Signs of spoilage include an unsealed jar, a bulging lid, streaking of dried foods that start at the top of the outside of the jar, rising air bubbles inside the jar or unnatural coloring of the food inside the jar.
Other spoilage signs are spurting liquid or unnatural odors when the jar is opened and mold growth (white, blue, black or green) on the food surface or under the lid.
Do not taste food from any jar with an unsealed lid or one that shows signs of spoilage.
Our food preservation class originally planned for Tuesday, June 17 had to be re-scheduled due to low registration and will be re-scheduled in July. If interested in registering for the workshop, please call the Carroll County Extension office at (502) 732-7030 for the new workshop date.
For instructions on how to safely dispose of spoiled low-acid foods, please visit the National Center for Home Food Preservation website at http://nchfp.uga.edu/how/store/store_home_canned.html.
References: National Center for Home Food Preservation. (n.d.). Frequently Asked Canning Questions. Retrieved September 17, 2013, from http://nchfp.uga.edu/questions/FAQ_canning.html
National Center for Home Food Preservation. (n.d.). Storing Home Canned Foods: Identifying and Handling Spoiled Canned Food. Retrieved September 17, 2013, from http://nchfp.uga.edu/how/store/store_home_canned.html
Source: Debbie Clouthier, Extension Associate for Food and Nutrition, University of Kentucky; College of Agriculture, Food and Environment
Grace Angotti is Carroll Co. Extension agent for family and consumer sciences. Call her at (502) 732-7030 or send e-mail to email@example.com.