A pungent, colorless liquid acid that is the primary acid in vinegar (vinegar is 5% acetic acid). Acetic acid is what makes vinegar sour.

Any substance in a class of sour compounds.

The vertical elevation (distance in feet or meters) of a location above sea level.

An ingredient used in older pickling recipes to add crispness and firmness to pickles. Alum, if consumed in large doses, may cause nausea and/or gastrointestinal problems and is no longer recommended for use in pickling recipes. If used, it must be thoroughly rinsed away. The chemical name is potassium aluminum sulfate.

A substance, such as citric acid (lemon or lime juice), ascorbic acid (vitamin C) or a blend of citric and ascorbic acids, that inhibits oxidation and controls browning of light-colored fruits and vegetables. Antioxidants are believed to neutralize free radicals, harmful particles in your body that can cause long-term damage to cells and lead to disease.

Any one of many synthetically produced non-nutritive sweet substances. Artificial sweeteners vary in sweetness but are usually many times sweeter than granulated sugar.

The chemical name for vitamin C, a natural, water-soluble vitamin that is commercially available in a concentrated form as white, odorless crystals or powder. It is used as an antioxidant to inhibit oxidation and control browning of light-colored fruits and vegetables.

Microorganisms, some of which are harmful, found in the soil, water and air around us. Some bacteria thrive in conditions common in low-acid preserved food and produce toxins that must be destroyed by heating to 240F (116C) for a specified length of time. For this reason, low-acid foods must be processed in a pressure canner.

See screw band.

To submerge a food in boiling water or steam for a short period of time, done to loosen the skin or peel or to inactivate enzymes. Blanching is immediately followed by rapidly cooling the food in ice water.

To heat a liquid until bubbles break the surface. At sea level, this happens at 212F (100C). At elevations above 1,000 feet (305 m), the boiling point is reached at a lower temperature. A boil is achieved only when the liquid is continuously rolling or actively bubbling. See also boil gently or simmer or boil, full rolling.

To cook food gently just below the boiling point (180F to 200F/82C to 93C). Bubbles rise from the pot bottom, only slightly disturbing the surface of the food.

A rapid boil, usually foaming or spurting, that cannot be stirred down, achieved at a temperature of 220F (104C). This stage is essential for attaining a gel when making cooked jams or jellies.

The temperature at which liquid reaches a boil (212F/100C at sea level).

A large, deep saucepan equipped with a lid and a rack to lift jars off direct heat. The pot must be deep enough to fully surround and immerse jars in water by 1 to 2 inches and allow for the water to boil rapidly with the lid on. If you don't have a rack designed for preserving, use a cake cooling rack or extra bands tied together to cover the bottom of the pot.