The reaction that takes place when cut fruits and vegetables are exposed to the oxygen in the air. Oxidation causes the cut surface of the produce to brown and can also lead to texture changes.

A pure, refined wax used in an older fresh preserving method. The wax was melted and poured over soft spreads in the jar. It is not a reliable method of preventing contamination by microorganisms, and in many instances mold growth will occur. Since no heat processing takes place, paraffin wax has not been recommended as a safe closure for soft spreads for many years.

A naturally occurring carbohydrate found in fruits and vegetables that is responsible for cell structure. The natural pectin content decreases as fruits and vegetables ripen. Thus, they become soft and lose their structure. Pectin is available commercially in powdered and liquid forms. Commercial pectin is used to make jams, jellies and other soft spreads.

A measuring system in chemistry for determining the acidity or alkalinity of a solution. In preserving, foods are separated into high-acid and low-acid. A boiling water canner is used for processing high-acid foods; a pressure canner must be used for processing low-acid foods.

A crisping agent that uses calcium chloride, a naturally occurring salt found in some mineral deposits, to enhance the texture of pickles."Pickle Crisp" Granules may be added to jars of quick-process or fresh-pack pickles before processing. 

Preserving food, especially cucumbers and vegetables, in a high-acid (vinegar) solution, often with spices added for flavor. Pickled foods must be processed in a boiling water canner.

A white, almost insoluble powder, also known as slaked lime, used in some older pickling recipes to add crispness to pickles. Due to its caustic nature, pickling lime is no longer recommended for making homemade pickles. Failure to remove lime adequately may increase the risk of botulism. Lime can also cause gastrointestinal problems if too much is ingested.

See salt, pickling or preserving.

To prepare foods to prevent spoilage or deterioration for long periods of time. Some methods of preservation are fresh preserving (home canning), freezing, dehydration, pickling, salting, smoking and refrigeration. The method used determines the length of time the food will be preserved.

A soft spread in which the fruit is preserved with sugar so it retains its shape and is transparent, shiny, tender and plump. The syrup varies from the thickness of honey to that of soft jelly. A true preserve does not hold its shape when spooned from the jar.

A tall, usually heavy pot with a lid that is locked in place and a pressure-regulating device. The lid is fitted with a safety valve, a vent and a pressure gauge. Pressure canners are used to process low-acid foods, because steam at 10 lbs (68 kPa) of pressure (at sea level) will reach 240F (116C), the temperature needed to destroy harmful bacteria that thrive in low-acid foods.

The fresh preserving method used to heat-processs low-acid foods. Low-acid foods must be processed in a pressure canner in order to destroy potentially harmful bacteria, their spores and the toxins they produce. In practical terms, this can be done at 240F (116C). Because the steam inside the canner is pressurized, its temperature can exceed the boiling point of water (212F/100C). In a weighted-gauge canner at sea level, the temperature will reach 240F (116C) at 10 lbs (68 kPa) of pressure.

Blanching or treating produce with an antioxidant to prevent browning, slow enzyme action or destroy bacteria.

Heating filled jars of food to a specified temperature for a specified time to inactivate enzymes and destroy harmful molds, yeasts and bacteria. Heat processing is essential for the food safety of all home-preserved foods. Processing destroys microorganisms that are naturally present in food and/or enter the jar upon filling. It also allows gases or air to be vented from the jar to create an airtight vacuum seal as the product cools, thus preventing recontamination of the food.

The time in which filled jars are heated in a boiling water canner or a pressure canner. The processing time must be sufficient to heat the coldest spot in the jar. The processing time is specified for every current, tested fresh preserving recipe and depends on several factors, such as acidity, type of food product and size of jar.