Fresh foods are perishable because they contain a high percentage of water. The practice of canning preserves fresh food by removing oxygen, destroying enzymes, and preventing the growth of bacteria, yeasts and mold.
It is important to follow these proper canning practices: • carefully selecting and washing fresh produce, • peel according to recipe, • hot packing many foods, • adding acids (lemon juice or vinegar) to some foods, • using acceptable jars and self-sealing lids, • processing jars in a boiling-water or pressure canner for the correct period of time.
What is foodborne botulism? Fast Facts • Illness caused by ingestion of foods containing the neurotoxin produced by C. botulinum. • Pressure canning is the only • Most often associated with improperly processed safe method for canning meat, home canned foods. poultry, seafood and low acid Symptoms include: Clostridium • vegetables. • Weakness and vertigo • The bacteria,, is only destroyed in • Blurred, double vision botulinum • Difficulty swallowing, speaking and breathing low-acid foods when properly Digestive upset spores survive • processed in a pressure canner. • Possible death from suffocation • C. botulinum hours at boiling water Adapted from FDA Bad Bug Book and National Center for Home temperatures in low acid foods. Food Preservation
Food Acidity • The pH of a food indicates how much acid is present and is measured on a scale of 0 - 14; the lower the pH the more acid is present. • Low-acid canned foods are not acidic enough to prevent C. botulinum growth. • Foods may be naturally acidic or acidified by pickling, fermenting or directing adding acid. • Adding lemon juice citric acid or vinegar increases foods’ acidity by lowering pH.
Low-acid foods: Acid foods: pH of 4.6 or higher pH of 4.6 or lower • Fresh vegetables (except • Sauerkraut most tomatoes) • Pickles • Meats • Jams • Seafood • Jellies • Poultry • Marmalades Recommendations
Jars and Lids • Regular and wide-mouth Mason type, Pressure Canners threaded, home canning jars with self- Modern pressure canners: sealing lids are the best choice. lightweight With careful use and • • thin-walled kettles handling, Mason jars may be • turn-on lids reused but require new lids • Equipped with: each time. jar rack Before use, wash empty jars • • gasket in hot water and rinse well, • dial or weighted or wash in a dishwasher. • gauge All jams, jellies, and pickled • automatic vent/ products processed less than 10 minutes • cover lock should be filled into sterile empty jars. vent or steam port with Do not use lids that are • • counterweight or weighted old, • gauge • dented, • safety fuse. • deformed, or • contain sealing gasket defects. Unsafe Canning Methods Tips and Tricks • Open-kettle canning • Process freshly filled jars in After filling jars: conventional ovens, microwave • Release air bubbles by inserting a flat ovens, and dishwashers, plastic (not metal) spatula between food • Using steam canners and jar. Slowly turn jar and move spatula • Using canning powders up and down • Using jars with wire bails and allowing glass caps bubbles to • Using one piece zinc porcelain- escape. lined caps • Adjust headspace if needed. • Clean jar rim (sealing surface) with Remember dampened paper towel. All pressure canners • Place lid, gasket down, onto cleaned jar- must be vented for sealing surface. 10 minutes before • Do not retighten lids after processing. they are pressurized.
Adapted from the National Center for Home Food Preservation website at: nchfp.uga.edu
For more information, contact Benjamin Chapman [email protected]