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Food Preservation Methods for Low Acid Foods

The bacterium that causes botulism, a food poisoning with deadly consequences, grows in warm, moist, low-acid environments devoid of air. Canned low-acid foods, if not processed properly, are an ideal location for the bacterium to grow. If you wish to preserve low-acid foods by canning, you must follow safety guidelines to ward against botulism or choose a different method of preservation.

  1. Pressure Canning

    • All fresh vegetables, legumes, meats, fish, milk, figs and some tomatoes have a Ph higher than 4.6, making them low-acid foods. Instead of using a boiling water canner to process these foods, as you would with jams or fruits, process them in a pressure canner. Wash, prepare and pack your foods as desired, then screw the lids on your jars. Follow the directions for your type of pressure canner, since models vary slightly in use. The amount of water you need to process your food may vary as well so follow recipe guidelines from the National Center for Home Food Preservation. Pressurize the jars for as long as recommended -- usually 20 to 45 minutes, to be sure of safe processing.

    Pickling

    • The addition of vinegar to low-acid foods raises the acidity level enough for safe storage. A variety of vegetables, salads, slaws, chutneys and eggs can be preserved using this method. Recipes vary widely depending on what you pickle and your desired end result. Some vegetables, including sauerkraut and regular dill pickles, process through several weeks' worth of brining to produce lactic acid. Others are canned in a solution of at least 5 percent acid vinegar and seasonings. Fruit or vegetable relishes and chutneys are cooked in a vinegar and spice mix, then canned and processed in a boiling water canner.

    Drying

    • Drying low-acid foods removes most of the moisture necessary for bacteria to grow. Meat and game is well-suited for drying, creating a chewy jerky product. Sweeter vegetables such as butternut squash can be baked, pureed and blended with a fruit puree to create vegetable and fruit leathers. Dried tomatoes are a useful culinary staple, whether used dried or rehydrated, dried onion and garlic are handy in the spice cupboard, and dried peas and corn can be lightweight additions to your pantry. Beans and other legumes are traditionally dried for storage, as well. Dry your foods in the oven on racks, on trays in the sun, or in a food dehydrator.

    Curing

    • Salting is one way to preserve low-acid meats and seafoods, often done with ham, bacon, corned beef and salt cod. Packing a thick layer of salt around the outside of a meat product draws the moisture from the interior of the food, making it impossible for bacteria to grow. Commercial curing mixes make it easy for the home preserver to measure the right amount of salt, saltpeter or nitrates for preservation. A variety of spices and seasonings are used to add flavor to the meat before and during curing, while smoking gives the meat a distinct pink ring and rich flavor.

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