Glossary


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L (liter).

A metric unit of volume. One liter is similar in volume to 1 U.S. quart.

lactic acid.

The acid produced during fermentation. The fermentation process converts the natural sugars in food to lactic acid, which, in turn, controls the growth of undesirable microorganisms by lowering the pH (increasing the acidity) of the food product and its environment. Lactic acid also adds a distinctive tart flavor and transforms low-acid foods into high-acid foods that can be safely processed in a boiling water canner.

lemon juice.

Juice extracted from lemons that is added to food products to increase the acidity. Lemon juice can also be purchased commercially. In fresh preserving, lemon juice is added to certain foods to increase acidity and ensure proper processing. In some soft spread recipes, especially those prepared with added pectin, the acid in the lemon juice also aids with gelling. The acidity of freshly squeezed lemon juice is variable, depending on the lemon variety and harvest conditions, whereas bottled lemon juice is produced to consistent acidity standards. In recipes that specify bottled lemon juice, it is crucial for the success of the final product not to use freshly squeezed lemon juice. Where bottled is not specified, either freshly squeezed or bottled lemon juice may be used.

lid.

A flat metal disc with a flanged edge lined with sealing compound used in combination with a metal screw band for vacuum-sealing fresh preserving jars.

lime.

See pickling lime.

long-boil soft spread.

A sugar and fruit mixture boiled to concentrate fruit’s natural pectin and evaporate moisture until a thick or gelled texture is achieved. Long boiling works best with fruits containing naturally high pectin levels. It yields smaller quantities per amount of fruit used and creates a caramelized fruit flavor. It may require a smaller measure of sugar as an ingredient, but the final cooked-down product isn’t necessarily lower in sugar than other products.

low-acid food.

A food that contains little natural acid and has a pH higher than 4.6. Vegetables, meat, poultry and seafood are all low-acid foods. Bacteria thrive in low-acid foods. The only recommended and practical means of destroying bacteria naturally found in low-acid foods is to heat the food to 240ºF (116ºC) (at sea level) for a specified time in a pressure canner.

low-methoxyl pectin.

A type of pectin that does not require the presence of sugar to produce a gel when making jams and jellies. No sugar needed fruit pectins are usually low-methoxyl.

marmalade.

A soft spread that contains pieces of citrus fruit and peel evenly suspended in transparent jelly. Marmalade is cooked in small batches and brought rapidly to, or almost to, the gelling point. Marmalades are similar in structure to jam.

mason jar.

A glass jar that is suitable for heat processing food and/or liquids using a boiling water canner or a pressure canner. Mason jars are designed to seal with two-piece metal closures and to withstand the temperatures and reuse associated with fresh preserving. True mason jars also conform to specific shapes and capacities compatible with established safe heat processing methods and times. The jars are available in regular mouth (70 mm) and wide mouth (86 mm) styles and in capacities ranging from 4 ounces (125 mL) to 1 quart (1 L). Most mason jars have rounded shoulders, but some have straight walls. Straight-walled mason jars can be used for freezing as well as fresh preserving. See also straight walls.

measures or measuring cups.

Standard kitchen utensils used to accurately measure liquid or dry ingredients. Liquid measures are commonly glass or plastic and have a handle and a pour spout. Dry measures can be either stainless steel or plastic. Both types are available in imperial (cups) and metric (mL) sizes.

metal band.

See screw band.

microorganism.

A living plant or animal of microscopic size, such as molds, yeasts or bacteria, that can cause spoilage in preserved or frozen foods.

mL (milliliter).

A metric unit of volume, 1/1000th of a liter. Measures for dry ingredients are available in 1, 2, 5 and 25 mL spoons and 50, 125 and 250 mL dry measures. Metric liquid measures, usually glass or plastic, show levels for quantities divisible by 10.

mold.

Microscopic fungi that grow as silken threads and appear as fuzz on food. Molds thrive on acids and can produce mycotoxins. Mold is easily destroyed at processing temperatures between 140ºF and 190ºF (60ºC and 88ºC).

mycotoxins.

Toxins (poisons) produced by some species of molds that grow on high-acid foods.

open-kettle canning/preserving.

A fresh preserving method in which hot foods are ladled into jars and two-piece closures are applied. Since no heat processing takes place, this method is not recommended.

oven canning/preserving.

A fresh preserving method in which jars are placed in the oven and heated. This method is not recommended.

overnight.

A period of time from 8 to 12 hours.

oxidation.

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.

paraffin wax.

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.

pectin.

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.

pH (potential of hydrogen).

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.

Pickle Crisp® powder.

A crisping agent that uses calcium chloride, a naturally occurring salt found in some mineral deposits, to enhance the texture of pickles. Pickle Crisp® powder may be added to jars of quick-process or fresh-pack pickles before processing. Look for it where fresh preserving supplies are sold.

pickling.

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.

pickling lime (calcium hydroxide).

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.

pickling or preserving salt.

See salt, pickling or preserving.

preserves.

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.

preserve.

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.

pressure canner.

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 240°F (116°C), the temperature needed to destroy harmful bacteria that thrive in low-acid foods.

pressure canning/preserving method.

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 240°F (116ºC). Because the steam inside the canner is pressurized, its temperature can exceed the boiling point of water (212°F/100°C). In a weighted-gauge canner at sea level, the temperature will reach 240°F (116ºC) at 10 lbs (68 kPa) of pressure.

pretreatment.

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

processing or heat processing.

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.

processing time.

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.

produce protector.

A commercially available antioxidant that prevents cut fresh produce from browning when exposed to the oxygen in the air, a reaction known as oxidation.