Acetic acid: The main acid in vinegar characterized by a pungent odor. White distilled or cider vinegar used in home food preservation should be 5% acetic acid. (Vinegars of unknown acidity should NOT be used in home food preservation due to their unkown preservation properties.)

Acid: Acids in solution have a sour taste and a pH of less than 7. Common food acids include acetic acid, ascorbic acid, citric acid, and lactic acid.

Acidification: Some fruits and vegetables have pH values that fall close to 4.6, so precautions like adding an acid ingredient to home canned foods are necessary to assure safe canning--regardless of whether foods will be processed in a boiling water bath or a pressure canner. To acidify, add 1 Tbsp. of bottled lemon juice or 1/4 tsp citric acid per pint of fruit/vegetable. The acid can be added directly to each jar before filling it with the product. 

Acid Foods:  Foods that contain enough natural acid to result in a pH of 4.6 or lower. Also includes foods that have had vinegar added to them, or those produced by controlled microbial fermentation (e.g. fermented & pickled vegetables). Because microorganisms do not thrive in acid, these foods can be safely processed in a boiling water bath, with increased time adjustments made for higher elevations.

Altitude: In food preparation, the phrase 'high altitude' is commonly used in reference to the adjustments needed to compensate for changes in atmospheric pressure relative to a specific location's elevation above sea level. These conditions can cause cooking to take longer, liquids to evaporate faster and boil at lower temperatures, and leavening gases in breads and cakes to expand more quickly.

Anti-Darkening Treatment: Preventing the darkening of fruits after they are cut, peeled, stemmed, or pitted while being prepared for preservation. Commonly done using (1) a solution made with 1 tsp (or 3,000 mg) ascorbic acid with 1 gallon of water, or (2) a solution made with 1/2 cup bottled lemon juice with 2 quarts water, or (3) a solution made using a commercial ascorbic acid product.

Antimicrobial: Substances that destroy or inhibit the growth of microorganisms.

Antioxidant: An ingredient, such as lemon juice, ascorbic acid or a blend of ascorbic and citric acids, that inhibits oxidation and controls discoloration of light colored fruits and vegetables. 

Ascorbic acid: The chemical name for vitamin C. Used in food preservation to inhibit oxidation and control enzymatic browning of cut produce. Commercially available in a concentrated form as white, odorless crystals or powder. 



Bacteria: A group of microorganisms, some of which are harmful, found in the soil, water and air around us. Some bacteria (Clostridium botulinum) survive and produce toxins in conditions common in low-acid canned foods, and their spores can only be destroyed by heating to 240° F for a specified time. For this reason, low-acid foods must always be processed in a pressure canner.  

Bacteria, Yeasts and Molds: These microscopic organisms exist as single-cells or colonies. They abound in nature in the vegetative (viable) and spore (resistant, usually inactive) forms. They are always present in air, water and soil and on food crops, insects, rodents and humans. If not inactivated by the application of heat, they can cause spoilage or unsafe products.

Blancher: A 6- to 8-quart lidded pot designed with a fitted perforated basket to hold food in boiling water, or with a fitted rack to steam foods. Useful for loosening skins on fruits to be peeled, or for heating foods to be hot packed.

Blanching: The heat treatment of raw plant foods in boiling water or steam for a set period of time in order to inactivate enzymes, thus preventing the deterioration of color, texture, flavor, or nutrient content of foods.

Boiling: The heating of a liquid to 212° F (100° C) at sea level, so that it rolls/bubbles from top to bottom and changes to a vapor. The boiling point decreases as altitude increases, making it necessary for the home canner to increase processing times and/or use a pressure canner in order to destroy harmful bacteria.

Boiling Water Canner: A standard-sized, lidded kettle with a jar rack, large enough to completely immerse and fully surround canning jars and two-piece caps with water. Designed for heat-processing 7 quarts or 8 to 9 pints of high-acid foods in boiling water. 

Boiling Water Canning Method: The procedure for producing shelf-stable canned food or foods that are classified as acids (pH of 4.6 or lower). In this method,  jars of food are heated completely covered with boiling water. Safe for fruits, tomatoes and pickles as well as jams, jellies and other fruit preserves. Always use a tested recipe to make sure the product you are canning is safe for this method of preservation, and adjust for your elevation.

Botulism: A potentially fatal illness caused by consuming toxin produced by growth of the bacterium Clostridium botulinum. The spores can be present in soil or debris present on raw foods. Using the correct processing temperature and time to preserve low-acid foods will destroy toxin-producing spores. Present in soil or debris on raw foods, the spores can survive and grow in any tightly sealed jar of low-acid food that has not been processed correctly. Using a tested recipe and the correct processing temperature and time for processing low-acid foods is the only way to assure the toxin- producing spores are destroyed. As an added safety precaution, boil all home-canned, low-acid foods for 10 minutes before tasting to destroy any toxin that could be present.

Brining: The process of soaking food in a salt solution. Commonly used in making fermented pickles or preparing meat or fish for smoking. 

Buckling: Canning lids  can become bent or deformed as air forces its way out of a jar during the canning process. This usually results from tightening the screw band [ring] too tightly, preventing air from venting from a jar during processing. Buckled lids may not be sealed properly.

Butcher Wrap: A type of coarse, sturdy paper that is used to wrap meats and fish. It is common to find butcher paper that has been waxed or oiled to resist leaks. Butcher wrap is a popular method of wrapping irregular cuts of meat, fish and poultry prior to freezing. 



Canning: A method of preserving food in air-tight vacuum sealed containers and heat processing sufficiently to enable storing the food at normal home temperatures. 

Canning/Pickling Salt: Salt that does not contain additives for anti-caking or iodine that are found in regular table salt.

Cap: The two-piece vacuum closure for sealing home canning jars. The set consists of a metal band (ring) and a flat metal lid. The lid has a flanged edge and sealing compound.

Case Harden: When dehydrating food, the formation of a hard shell on the outer portion of produce pieces that traps moisture inside, reducing quality and causing deterioration.  

Citric Acid: An acid derived from citrus fruits (i.e. lemons, limes) that can also be purchased commercially. It increases the acidity of foods and prevents fruit and vegetable discoloration, but not as effectively as ascorbic acid.

Cold Pack: A canning procedure in which jars are filled with raw (uncooked) food and covered with boiling brine, water, syrup or juice prior to being sealed and processed.

Conditioning: After drying fruits and vegetables, some pieces may be more moist than others due to their size and placement during drying. Conditioning evenly distributes moisture among all the pieces and reduces the chance of spoilage, especially from mold.

Conserves: Products with a consistency like jam, that are easily spreadable and not stiff.  Made by combining fruits, and may contain citrus fruits, nuts, raisins, or coconut. 

Cool Place: Term used when referring to a storage place for home canned food. The ideal temperature is 50-70º F. 



Dehydrator: A small electrical appliance used for drying foods indoors. A food dehydrator has an electrical element for heat and a fan and vents for air circulation. Dehydrators are efficiently designed to dry foods quickly at 140-165º F.  

Dehydration/Drying: The process of removing moisture (i.e. water) from food so that microorganisms cannot grow and enzyme action is slowed down. 

Depressurize: The release of pressure from within a pressure canner by allowing it to cool down naturally. 

Disinfect/Disinfectant: To destroy disease-causing bacteria or inactivate viruses under specific conditions. Disinfecting solutions are stronger than sanitizing solutions and should NOT be used on food preparation equipment, surfaces or utensils. Disinfectants are most suited for use on hard, high-touch surfaces such as railings and door knobs.   

Doneness for Jelly Products: There are 3 methods of testing the doneness in jellies made without added pectin. These include a temperature test (most dependable), a spoon or sheet test, and a refrigerator/freezer test. 

Dry Pack: Packaging frozen foods without the use of added liquids or sugar. 


Elevation: The vertical distance of a land location above sea level. Used to describe the height of the ground, or feature fixed to the ground in relation to sea level. At higher elevations, atmospheric pressure is lower and may impact cooking, baking, and preserving foods. Adjustments in cooking time, temperature, ingredients, and equipment may be necessary to ensure safety and quality. 

Enzyme: A naturally occurring protein in food that accelerates a specific flavor, color, texture, or nutritional change, especially when food is cut, sliced, crushed, bruised, or exposed to air.  Enzyme action slows down in frozen food, increases quickly at temperatures between 85º-120º F and stops at temperatures above 140º F. Proper blanching or hot-packing practices destroy enzymes and improve quality. 

Ethylene: A colorless gas that is produced by higher plants (plants with relatively complex characteristics, i.e. vascular systems and/or flowers). It is a plant hormone that stimulates the ripening and color change in fruit. 

Exhaust: Forcing air to escape from a jar of food or a pressure canner by applying heat. Exhausting or venting of pressure canners is necessary to prevent the risk of botulism in low-acid foods. 



Fermentation: Changes in food caused by intentional growth of bacteria, yeast, or mold to produce desirable products. Native bacteria ferment natural sugars to lactic acid, a major flavoring and preservative in sauerkraut and in naturally fermented dill pickles. Alcohol, vinegar, and some dairy products are also foods produced by microbial fermentation. 

Fingertip Tight: The amount of tightness needed to safely secure the lid and metal band onto a canning jar. The band should be screwed down evenly and firmly over the lid, just until resistance is met. This allows air to escape while heating but keeps the lid close enough to the jar to allow the sealing compound to seal after the jar comes out of the canner. Because air needs to be forced out of the jar during processing, a band that is too tightly attached can cause the lid to buckle or become deformed, and the jar to not properly seal.

Flash Freezing: Accelerated method of freezing foods often done at home by placing individual items on a baking sheet for quicker freezing before storing food in freezer bags, plastic freezer boxes, can-or-freeze jars or vacuum packages. 

Flat Sour Spoilage: A type of spoilage in canned vegetables caused by bacteria that give food an unpleasant flavor. It can be prevented by following correct methods of preparing, packing, processing and cooling foods.

Freezer Burn: Undesirable dehydration (moisture loss) of improperly packed frozen foods that results in loss of flavor, texture, and color.

Freezing: Reducing the temperature of foods so that microorganisms cannot grow; however, many can still survive.  Enzyme activity is also slowed down, but not stopped. 

Fruit Butter: Sweet spread made by cooking fruit pulp with sugar to a thick, spreadable consistency. It is thick enough to mound on a spoon. Spices are often added. 


Gasket: A rubber or rubber-like liner that helps seal the edges of a pressure canner and its lid to prevent steam from escaping. May be removable for cleaning or replacement. Not all pressure canners have gaskets, some have a metal-to-metal seal. 

Gauge: Stovetop pressure canners have either a dial gauge for indicating the pressure, or a weighted gauge for indicating and regulating the pressure.  

Weighted gauges are designed to "jiggle" several times a minute or to keep rocking gently when they are maintaining the correct pressure.

Dial gauges usually have a counterweight or pressure regulator for sealing off the open vent pipe to pressurize the canner. This weight should not be confused with a weighted gauge and will not jiggle or rock as described for a weighted gauge canner. Pressure readings on a dial gauge canner are registered on the dial, and only the dial should be used as an indication of the pressure in the canner. 

Gastroenteritis: An irritation or infection of the gastrointestinal tract, usually the stomach or small intestines. Symptoms are frequently nausea, vomiting, diarrhea, and cramps. The cause is often microbial toxin or infection. 



Headspace: An area left unfilled above food or liquids in home canning jars or freezer containers. In canning, headspace allows for the expansion of foods and liquids when jars are heated and for the forming of a vacuum as the jars cool. Headspace also provides space for expansion in containers as foods or liquids freeze.  

Heat Processing: Treatment of jars with sufficient heat to enable storing food at normal home temperatures. 

Hermetic Seal: An absolutely airtight container seal which prevents reentry of air or microorganisms into packaged foods. 

Hemorrhagic Colitis: Abdominal cramps and bloody diarrhea, without fever, associated with infection with Escherichia coli O157 (E. coli). 

High-Acid Food: Foods which contain enough natural acid to result in a pH of 4.6 or lower, and/or foods which may contain very little natural acid but have a sufficient amount of added vinegar or lemon juice added to them to be treated as high-acid foods. May be safely processed in a boiling-water canner and, if necessary, with additional processing time adjustment made for high elevation locations.

Home Canning: Preserving fresh or prepared foods in glass home canning jars that seal with two-piece vacuum caps and using a heat process to destroy microorganisms that cause spoilage. 

Honeys: Sweet syrups made by cooking fruit juice or pulp with sugar until thickened, but not thick enough to mound or hold its shape. Should be pourable. 

Hot-Pack: Filling canning jars with precooked, hot foods (heated in an open vessel in water, juice, syrup or steamed) prior to processing. Preferred method when using firm food. This method permits a tighter pack, reduces floating and requires fewer jars.  

Humidity: The amount of water vapor in the air. Relative humidity (RH) is a frequently used measurement of humidity, expressing the moisture content of the air as a percentage of the maximum moisture content at a given temperature.



Infection: Disease caused when a bacteria, parasite, or virus multiplies within the body. Salmonella, norovirus, and Cyclospora are examples of foodborne microogranisms capable of causing infections. 

Intoxication: Ingestion of toxins at levels to cause illness. When referring to foodborne illness, the food contains toxins formed by bacteria as they grew in the food item. 



Jams: Made by cooking crushed or chopped fruits with sugar. They are thick, sweet spreads that tend to hold their shape but are less firm than jelly. The shape of fruit pieces are not retained when making jam. Jam has a uniform consistency and is thick enough to spread. 

Jar: A home canning jar, sometimes called a Mason jar, designed to withstand repeated use and heat processing in boiling-water and steam-pressure canners. 

Jellies: Usually made by cooking fruit juice with sugar. A good jelly will be clear or translucent (depending on the type of juice), free from sediment, pulp or crystals. It should be firm enough to hold its shape when turned out of the container but should quiver when the container is moved. When cut, it should be tender yet retain the angle of the cut. Jelly should have a flavorful fresh fruit taste that is not too tart and not too sweet.   

Jerky: Lightweight, dried meat product that is a handy food for backpackers, campers, and outdoor sports enthusiasts. It requires no refrigeration. Can be made from almost any lean meat, including beef, pork, venison or smoked turkey breast. 



Lactic Acid: Acid produced by lactic acid bacteria. It acidifies and flavors fermented pickles, sauerkraut, and also cheese, breads, and many other foods. 

Lactic Acid Bacteria: A large group of bacteria that produce lactic acid as a by-product of sugar fermentations. They are primarily of the genera Lactobacillus and Streptococcus, and are generally more tolerant of low pH environments than many other bacteria. They are common in nature and are often associated with plant materials. 

Leather: Homemade fruit or vegetable product made by pouring a thin layer of pureéd fruit/vegetable onto a flat surface for drying. When dried, the tasty, chewy fruit/vegetable product is pulled from the surface and rolled and/or cut into strips.  

Lid: The flat metal disc with a flanged edge and a sealing compound on its underside used in combination with metal screw band for vacuum sealing glass jars.

Lime: Food-grade pickling lime (calcium hydroxide) may be used as a firming agent during the pickling process. The calcium combines with natural pectin in cucumbers to form calcium pectate, giving pickles a firmer texture. Fresh cucumbers can be soaked in a lime-water solution for 12-24 hours, but excess lime absorbed by the cucumbers must be removed to make safe pickles (drain solution, rinse, and re-soak in fresh water for 1 hour- repeat 2x). 

Low-acid Foods: Foods which naturally contain very little acid and have a pH above 4.6. The acidity in these foods is insufficient to prevent growth of the bacterium Clostridium botulinum. Vegetables, some tomatoes, figs, all meats, fish, seafoods, and some dairy foods are low acid. To control all risks of botulism, jars of these foods must be (1) heat processed in a pressure canner at 240º F (116º C) or (2) acidified to a pH of 4.6 or lower before processing in boiling water to assure the destruction of spoilage microorganisms.



Marmalades: Soft fruit jellies containing small pieces or slices of fruit or fruit peel (often citrus) evenly suspended in the transparent jelly. 

Metal Band: A threaded screw band used in combination with a flat metal disc to form a two-piece closure for vacuum sealing glass jars.

Microorganisms: Microscopic-size organisms including bacteria, yeast and molds. They grow rapidly in suitable conditions (i.e., moisture, nutrients, temperature and acidity) and reach very high populations quickly. Microorganisms can cause food spoilage and some harmful microbes cause foodborne illness which can result in death.

Mold: Microscopic fungi whose growth on food is usually visible and colorful (may appear as fuzz).  Molds thrive on many food products, even acids, and can produce mycotoxins. Recommended deyhdration methods, heat processing (temperatures between 140º and 190º F) and sealing of canned goods prevent their growth on these foods. 

Mycotoxins: Toxins (poisons) produced by the growth of some species of molds on food, including high-acid foods.  



Natural Pectin: The pectin level found naturally in fruits and vegetables. Natural pectin content varies by product, and declines with ripening, leading to softening of fruits and vegetables.

Non-pathogenic: Microorganisms in food or water that do not cause human illness. These include most species of bacteria, yeasts, and molds. 



Outbreak: A foodborne illness outbreak is defined as two or more people experiencing the same illness after eating a common food or meal. 

Open Kettle Canning: An old-style method of canning that is no longer considered to be safe. The food is cooked in an open kettle and then quickly put into jars and sealed without further processing. As foods are being transferred from the kettle to jars, there is an opportunity for airborne mold spores and bacteria to contaminate the food, increasing the risk of spoilage and foodborne illness. Foods canned this way frequently have weak seals due to low vacuum pressure or too much air, which permits rapid loss of quality in foods and can be unsafe. 

Overnight: In cooking terms, a time period typically between 8 to 12 hours. 



Pasteurize: Heating of a specific food enough to destroy the most heat-resistant pathogenic microorganism known to be associated with that food. 

Pathogens: Microorganism capable of causing human illness. Foodborne pathogens include certain species of bacteria, viruses, molds, and parasites. 

Pectin: A naturally occurring carbohydrate found in the cell walls of fruits (i.e. apples, peaches, citrus) and vegetables (i.e. carrots, green beans).  Extracted pectin, commercially available in powdered or liquid form, is used widely as a gelling or thickening agent and a food stabilizer. 

Pectin Substitute: A substance used in place of pectin to form a gel-like structure by binding liquid. Pectin substitutes have traditionally been used to make reduced- and no-sugar fruit spreads.

Perishable Food: A potentially-hazardous food or foods that require controlled temperature storage to prevent the growth of pathogenic organisms. Examples include meat, poultry, fish, milk, and eggs.  

Petcock Vent: A short hollow pipe that sticks up above the canner lid. When open, it allows air and steam to escape from the canner. When closed, it holds the steam inside. On newer canners the vent is closed or opened using a separate pressure regulator weight. On older canners, the vent may be closed using a valve or screw that you can turn. 

pH (Potential of Hydrogen): A measure of acidity or alkalinity using a scale ranging from 0 to 14. A food is neutral when its pH is 7.0. Values less than 7 are acidic while values greater than 7 are alkaline (basic). pH is determined by measuring the available hydrogen ions in a food or other solution. 

Pickling/Acidifying: The practice of adding enough vinegar, lemon juice, or brining solution to a low-acid food to lower its pH to 4.6 or below for preservation purposes. Properly acidified or pickled foods can be safely heat-processed in boiling water.

Preserves: Small, whole fruits or uniformly-sized pieces in a thick, slightly-gelled sugar syrup. The fruit should be tender and plump and there should be no mushy or broken-up fruit tissue. The color should be characteristic of the fruit, and fruit pieces should be translucent to clear. 

Pressure Canner: A specially-designed metal kettle with a lockable lid used for heat processing low-acid foods. These canners have jar racks, one or more safety devices, systems for exhausting air, and a way to measure or control pressure. Canners with 16- to 23-quart capacity are common. The minimum volume of canner that can be used is one that will contain 4 quart jars. Use of pressure saucepans with smaller capacities is not recommended for home food preservation. 

Pressure Canning: The only safe method of canning vegetables, meats, poultry and seafood. Jars of food are placed in 2 to 3 inches of water in a pressure canner which is heated to a temperature of at least 240º F. This temperature can only be reached in a pressure canner. 

Pressure Gauge: The instrument on a pressure canner lid that registers the pressure inside the canner.

Pressurize: To increase the pressure inside a sealed pressure canner to a level higher than the outside, by applying heat to the canning vessel. 

Pre-treatment: Blanching or treating produce with an antioxidant to set color, slow enzyme action or destroy bacteria. 

Processing: Sterilizing jars and the food they contain in a steam-pressure or boiling-water canner to destroy  molds, yeasts, bacteria and enzymes that can cause illness or product spoilage.

Processing Time: The amount of time filled canning jars are heated in a boiling water canner or a pressure canner to inactivate enzymes and sufficiently destroy microorganisms in order to achieve a shelf-stable product. Processing times are determined scientifically for a specific type of food mixture and are based upon the time and temperature required to obtain lethality in the coldest part of the jar.

Produce Protector: An ascorbic acid and dextrose blend used to inhibit oxidation and control discoloration of light color fruits and vegetables. 

PSI (Pounds per Square Inch): The primary unit of measure for pressure. Pressure gauges on canners display pressure as a PSI measurement. 



Rancidity: Changes that can occur when fat, such as that found in meat or plant oils, is exposed to oxygen over a period of time resulting in an unpleasant taste and aroma. Rancidity can be controlled by using a wrapping material or packaging which does not permit air to reach the product. It is also advisable to remove as much air as possible from storage bags or containers to reduce the amount of air in contact with the product.

Raw Pack: Filling canning jars tightly with raw, unheated food. Some foods, especially fruits, will float in the jars using this method. Additionally, the air trapped in and around some foods may cause discoloration within 2 to 3 months of storage.  

Rehydration (Reconsitution): Restoring water (liquid) to a dried food. 

Reprocessing: Foods from jars that did not seal can be re-processed, but this must be done within 24 hours! 

Other safe storage options for jars that do not seal:

Reservoir: The long-term animal host of an infectious disease pathogen that can directly or indirectly transmit pathogens to humans. Most often, the hosts are immune to effects of the pathogen. Poultry can be Salmonella reservoirs.  

Respiration: The process that allows plants to convert the stored energy of carbohydrates, made by photosynthesis, into energy for metabolic processes. Respiration occurs in the presence of oxygen, both before and after harvest, meaning fruits and vegetables continue to generate energy in the form of heat after harvest. Reducing the respiration rate by cool temperatures will slow down enzymatic processes that cause produce to degrade.

Ring: A threaded screw band used in combination with a flat metal disc to form a two-piece closure for glass jars. Also called a metal band.


Salt: In addition to being used for flavoring, salt is a component in a variety of preservation practices to prevent spoilage, to reduce the risk of pathogen growth, for tenderizing meat before drying (in marinade form), and aiding in fermentation and pickling processing. For home food preservation, canning salt is recommended because it does not contain additives for anti-caking or iodine, which are often included in regular table salt.

Sanitize/Sanitizer: To reduce the number of disease-causing microorganisms to a safe level. Sanitizing solutions are usually used for food contact surfaces. Common sanitizers  used in kitchens and food-processing plants include solutions containing chlorine, iodine, and quaternary ammonium. 

Shelf-Stable: Non-perishable foods which do not spoil unless handled carelessly are considered shelf-stable. Examples include sugar, flour, dry beans, pasta, dry mixes, and properly canned food. Shelf-life of shelf-stable food is determined by the length of time a food remains palatable-- that is, the food has not developed undesirable flavors or aromas due to rancidity and has not decreased in quality because of textural changes. 

Simmer: To cook food gently just below the boiling point (between 180º and 200º F). Bubbles will rise gently from the bottom of the pot and slightly disturb the surface of the food. 

Siphoning: The seepage of liquid out of canning jars during processing or upon cooling due to pressure fluctuations. 

Sodium Bisulfite: Combined with water and used as a sulfite dip to achieve a quick and easy long-term anti-darkening effect for prepared fruits. Ratio for dip is 3/4-1 1/2 teaspoons sodium bisulfite for each quart of water. 

Spice Bag: A closable fabric bag used to extract spice flavors in pickling solutions. Also called a 'bouquet garni'. 

Spoilage: Process by which food become unfit for ingestion. Caused by:

Spoilage Organisms: Bacteria, molds, and yeasts that degrade the taste or other quality of food. Signs of spoilage include broken seals, mold, gassiness, cloudiness, spurting or seepage of liquid, yeast growth, fermentation, slime, and disagreeable odors. Spoilage organisms do not cause the typical types of foodborne illness but ingesting spoiled foods may cause intestinal distress.   

Spore: A small, usually one-celled structure that is capable of quickly developing new cells. Bacterial spores form under adverse environmental conditions, allowing bacteria to survive. Once conditions become favorable, the spores will germinate. Fungal spores are microscopic units capable of reproduction and forming mold on foods.

Steam Canner (Atmoshpheric): Atmospheric steam canners are used for processing naturally acidic or properly acidified foods with natural or equilibrated pH values of 4.6 or below. They are not pressurized vessels used for processing for low-acid foods. Some of the key controls in addition to the acidity of the food product are:


Style of Pack: Form of canned food, such as whole, sliced, piece, juice, or sauce. The term may also be used to reveal whether food is filled raw or hot into jars. 

Sugar: Aids in gel formation, provides flavor, and acts as a preserving agent. Either beet or cane sugar can both be used and yield similar results. Sugar can be replaced by light corn syrup or honey in some recipes.

Sugar Pack: To sprinkle sugar over fruit and mix gently until the juice is drawn out and the sugar is dissolved. Soft sliced fruits (peaches, strawberries, figs, de-seeded grapes, plums, cherries, etc.) will yield enough syrup for covering if the fruit is layered with sugar and allowed to stand for 15 minutes. Some small whole fruits may be coated with sugar and frozen. 

Sulfite Dip: Process used to achieve the same long-term anti-darkening effect as sulfuring, but more quickly and easily. Either sodium bisulfite, sodium sulfite or sodium meta-bisulfite that are USP (food grade) or Reagent grade (pure) can be used. 

Sulfuring: An old method of pre-treating fruits. Sublimed sulfur is ignited and burned in an enclosed box with the fruit. The sulfur fumes penetrate the fruit and act as a pretreatment by retarding spoilage and darkening the fruit. The sulfur fumes also reduce the loss of vitamins A & C. Fruits must be sulfured outdoors where there is adequate air circulation. 

Sweet Spreads: Made by cooking fruit pulp with sugar to a thick, spreadable consistency. Spreads are thick enough to mound on a spoon. Spices are often added. 

Syrup: Made by cooking fruit juice or pulp with sugar until thickened, but not thick enough to mound or hold its shape. Should be pourable. Used to add liquid to canned or frozen food. 

Syrup Pack: Made by mixing water or juice extracted from some of the fruit with sugar. The mixture is heated to dissolve the sugar and is kept hot until ready for use. Syrups vary from very light to very heavy, which can be chosen to suit the sweetness of  the fruit and personal taste. 


Tested Recipe: One that has been tested scientifically to ensure that particular food mixture will be heated sufficiently in all parts within the jar to destroy both vegetative and spore forms of bacteria.

Testing Jelly for Doneness--Refrigerator/Freezer Test: Pour a small amount of boiling jelly on a plate, and put it in the freezing compartment of a refrigerator for a few minutes. If the mixtures gels, it should be done. During this test, the rest of the jelly mixture should be removed from the heat to prevent overcooking.

Testing Jelly for Doneness--Spoon or Sheet Test: Dip a cool metal spoon into the boiling jelly mixture and lift the spoon out of the steam so the syrup runs off the side. When the mixture first starts to boil, the drops will be light and syrupy. As the syrup continues to boil, the drops will become heavier and will drop off the spoon two at a time. When the two drops form together and "sheet" off the spoon, the jellying point has been reached. 

Tray Pack: An alternative to dry pack that can make fruits and blanched vegetables easier to remove from the container. Simply spread a single layer of prepared fruit or blanched vegetable on shallow trays and freeze. When frozen, promptly package and return to the freezer. The pieces remain loose and can be poured from the container and the package re-closed. Package tray packed fruits and vegetables as soon as they are frozen to prevent freezer burn. 

Two-piece Cap: The two-piece vacuum closure set recommended for home canning, consisting of a metal band and a flat metal lid. The lid has a flanged edge and sealing compound. 


Vacuum: The state of negative pressure that reflects how much air has been removed from within an air-tight container that has been processed. The higher the vacuum, the less air left inside the container.

Vacuum Packaging: A method to remove air from a container and seal the container to prevent air from re-entering without heat processing. Perishable foods must be refrigerated or frozen. This is not a substitute for home canning. 

Vacuum Seal: The state of negative pressure in a heat-processed jar of home-canned food. When the jar is heated, the air and food inside expand, forcing air out and decreasing the inside pressure. As the jar cools and the contents shrink, a partial vacuum forms preventing re-entry of air or microorganisms.  

Venting: Forcing air to escape from a jar by applying heat or permitting air to escape from a steam-pressure canner. Allows time for the formation of  an airtight vacuum seal. 

Vinegar: Cider or white vinegars with 5% acidity or higher can safely be used for home canning and pickling. This is the level of acidity in most commercially bottled vinegars. Do not use vinegar that is homemade or has unknown acidity. Do not dilute vinegar unless specified by recipe or it will lose its preservative effect. For a less sour product, add sugar rather than decrease vinegar. Vinegar can also be used to acidify tomatoes & tomato products (4 Tbsp. vinegar per quart or 2 Tbsp. vinegar per pint), but may cause undesirable flavors. 



Water Bath Canner: A large metal kettle/pot with a lid and rack or basket to keep glass jars from resting on the bottom of the kettle or from bumping together. The kettle must be deep enough for the water to be well over the top of the jars (by 1-2") and still have room to boil briskly. The water bath canner is recommended for foods that can be adequately processed at 212º F (100º C) such as fruit, tomatoes, fermented foods and food with vinegar added, jellies, jams and preserves.

Water Bath: Used to process foods at a boiling temperature (212º F at sea level). Recommended for processing acids foods such as fruits, tomatoes, pickles, and relishes. Heat from the boiling water is sufficient to destroy microorganisms which cause spoilage in acid foods. Jams, jellies, preserves, conserves, marmalades, butters, honeys and syrups are also processed in a boiling water bath canner. 



Yeast: Single celled fungal microorganisms that cause fermentation in foods and leavening in breads. Yeasts are inactive in foods that are frozen and are easily destroyed by processing at a temperature of 212º F.