Canning Dictionary

Acid Foods
Foods that contain enough acid to result in a pH of 4.6 or lower. Some foods may contain very little natural acid but have a sufficient amount of vinegar, citric acid or lemon juice added to them to be classified as acids in canning.

Antioxidant
Is an affect agent that inhibits the oxidation of cut fruits and vegetables as well as controls discoloration. Lemon juice, ascorbic acid or a blend of ascorbic and citric acid are all antioxidants.

Bacteria
Microorganisms which are found in the soil, water and air around us. In certain low-acid conditions, some bacteria can produce harmful toxins. Proper heat processing of low-acid foods in the steam-pressure canner destroys harmful toxins.

Band
A threaded metal band used in combination with a flat metal vacuum sealing lid to form a two-piece cap.

Blanch
To dip fruits and vegetables in boiling water to loosen their skins. Blanching vegetables in boiling water or steam also slows the action of enzymes.

Boil
To heat to 212°F at sea level.

Boiling-Water Canner
A deep kettle equipped with a jar rack and lid. It must be large enough to completely immerse capped canning jars, allowing 1 to 2 inches of water to cover jars. A boiling-water canner is required for heat processing high-acid foods.

Botulism
An illness caused by ingesting a toxin produced from the spores of Clostridium botulinum bacteria under conditions favorable for its growth. Proper selection, preparation, packing and heat processing destroys this bacterium in canned foods.

Cap
Two-piece metal closure used to form a vacuum seal on home canning jars. See Two-Piece Vacuum Cap.

Citric Acid
An acid derived from certain citrus fruits used to increase the acidity of tomatoes. It also controls discoloration of cut fruits.

Cool Place
A location with a temperature ideal for storing jars of home canned foods – usually between 50°F and 70°F.

Enzyme
A protein in foods that affects changes in flavor, color, texture, and nutritional value. The preservation methods for canning and freezing destroy the action of enzymes.

Headspace
The unfilled space in a home canning jar between the top of the food or liquid and the underside of the lid. Headspace is necessary for food expansion as jars are heated, and for forming a vacuum as jars cool.

Hot Pack
Filling hot jars with precooked, hot food prior to processing.

Jar
A glass container specially designed and heat-treated for use in home canning.

Lid
The flat metal disc with flanged edges, having a rubber-like sealing compound on its underside. Used as part of the two-piece vacuum cap for sealing home canning jars.

Low-Acid Food
Foods having a pH of 4.6 or higher. To destroy harmful bacteria, their spores and the toxins they produce, low-acid foods must be processed in a steam-pressure canner at 240°F. Adjustments are necessary at elevations higher than 1,000 ft. above sea level.

Microorganism
A microscopic living plant or animal which, if not destroyed by heat, can cause spoilage in canned and frozen food.

Mold
Microscopic fungi that appear as fuzz on food. Molds may grow on acid foods like jams, jellies and canned fruits. Proper heat processing inhibits mold growth.

Pectin
A natural substance, found in varying amounts in fruits, that acts to form a complex gelatinous structure. It is used to make jams, jellies and other soft spreads gel. Commercial powdered and liquid pectins are not interchangeable.

pH
A measure of acidity or alkalinity. On a scale 0 to 14, a value of 7 is neutral, values lower than 7 are increasingly acidic, and values higher than 7 are increasingly alkaline. In canning, a food’s pH determines the appropriate processing method.

Pickling
Preserving using a brine or vinegar solution to decrease pH levels to 4.6 or lower. All pickled foods must be processed in a boiling-water canner.

Processing
Sterilizing jars and the food they contain in a steam-pressure or boiling-water canner to destroy harmful microorganisms.

Raw Pack
Filling jars with raw, unheated food prior to processing. This term is preferred over “Cold Pack.”

Simmer
To cook just below the boiling point in the range between 180°F and 200°F.

Spice Bag
A muslin bag or cheesecloth square used to hold whole spices and/or herbs that is added to a mixture to extract flavorings during cooking. For Reusable Spice bags, see Order Online.

Steam-Pressure Canner
A heavy kettle fitted with a jar rack and a lid that can be locked in place and that has a safety valve, a vent and a pressure gauge. A steam-pressure canner is required for heat processing low-acid foods.

Syrup
A water/sugar or juice/sugar mixture used to add liquid to canned or frozen products.

Two-Piece Vacuum Cap
A metal closure for sealing home canning jars. It consists of a screw band and a flanged lid, the underside of which is coated with a rubber-like sealing compound.

Vacuum Seal
The absence of normal air pressure in jars that are airtight. After heat processing and upon cooling, air is forced from the jar causing a vacuum seal. The sealing compound on the lid prevents air from reentering.

Venting
Forcing air to escape from a jar by applying heat. Or, permitting air to escape from a steam-pressure canner.

Yeast
Microscopic fungi that cause fermentation in foods. They are easily destroyed at a temperature of 212°F.