Common canning terms

Understanding canning terms in research based food preservation books helps to make reading canning recipes easier.

There are many terms used when canning food. Across the state, Michigan State University Extension answers food preservation questions and offers educational workshops based on research based methods and recipes. Below are definitions of terms referred to in recipes and procedures when canning foods at home.

Acid foods (also referred to as high acid foods): This term refers to foods with a pH of 4.6 or less and contain enough acid so that Clostridium botulinum spores cannot grow and produce deadly poison. They are also called high acid foods. Acid foods include fruits, fruit juices, jellies, jams and other fruit spreads; tomatoes with added acid, pickles, relishes, and chutneys, tomato sauces, vinegars and condiments. Acid foods are canned safely in a water bath canner.

Citric acid: Is a form of acid that can be added to canned foods to increase the acidity of low-acid foods. Many factors now affect the acidity levels of tomatoes. It is recommended by the United States Department of Agriculture to add acid to all home canned tomatoes. To acidify, add ¼ teaspoon citric acid per pint or ½ teaspoon per quart to tomatoes and tomato juice. You can also acidify tomatoes using 1 tablespoon of bottled lemon juice per pint or 2 tablespoons per quart.

Head space: That space in a jar between the top of the food, or liquid, and the inside of the lid is called headspace. Always follow directions for the correct headspace for different foods.

Low-acid foods: Low-acid foods include vegetables, meats, poultry, seafood and soups. All low-acid foods must be processed in a pressure canner to be safe.

Open kettle: Open kettle processing is where food is heated to boiling, then put into canning jars with a two-piece lid and allow the heat of the jar to cause the lid to seal. This method of canning is no longer recommended due to the food not being heated adequately to destroy the spoilage organisms, molds, yeasts and does not produce a strong seal.

Pickling or canning salt: This salt does not contain iodine or anti-caking additives that are found in table salt. It helps to make a clear brine or liquid when canning. Table salt can make a canned liquid appear cloudy.

There are many more terms that are related to canning foods other than these. You can find them in research based food preservation books such as updated Ball Blue Books, So Easy to Preserve, the USDA Complete Guide to Home Canning and Preserving and Extension bulletins.

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