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Abundant fresh fruits, vegetables, meats, poultry, and seafood are savored during the peak of the season and safely preserved to enjoy all year. What was once done out of necessity, today has become an opportunity to take control of the food you and your family consume. These beautiful jars of home-canned goodness will give you the satisfaction of knowing the quality and freshness of the food in your pantry. They will also ease your meal planning and take a bite out of your garbage and recycling needs. Reusable jars and bands can be used for many years. The flat lid is the only piece to be discarded. Home canning is well worth the effort when you take that first delightful bite of food canned in your own kitchen!

Canning Introduction
If you're a novice to pressure canning, this outline will give you basic knowledge of the terminology and instruction of canning. The key to successful canning is to understand the acidity and spoilage factor of the food you wish to can, as well as the acceptable canning methods to process those foods. Invisible microorganisms exist naturally on fruits, vegetables, meat, poultry, and seafood. Yet they are not a problem unless food is left to sit for extended periods of time, causing food spoilage. This is nature's way of telling us when food is no longer fit to eat.

There are four basic agents of food spoilage — enzymes, mold, yeast, and bacteria. Canning will interrupt the natural spoilage cycle so food can be preserved safely.



Molds, yeast, and enzymes are destroyed at temperatures below 212°F, the temperature at which water boils (except in mountainous regions). Therefore, boiling water canning is sufficient to destroy those agents.

Bacteria, however, are not as easily destroyed. The bacterium Clostridium botulinum produces a spore that makes a poisonous toxin which causes botulism. This spore is not destroyed at 212°F. In addition, this bacterium thrives on low acid foods in the absence of air. Therefore, for a safe food product, low-acid foods need to be processed at 240°F, a temperature only achieved with pressure canning.

Determining the Method
The level of acidity in the food being canned determines which method of canning is required, either boiling water canning or pressure canning. For the purpose of home canning, foods are categorized as low acid and high acid.


Low acid:
Foods that are low acid have a pH value higher than 4.6 and include vegetables, meats, poultry, and seafood. Low acid foods must only be processed using the pressure canning method.

High acid: Foods that are high acid have a pH value of 4.6 or less and include fruits, jams and jellies, properly pickled vegetables and properly acidified tomatoes. Most fruits are naturally high acid. Pickles and tomatoes, which are not high acid, are made high acid with the addition of lemon juice or vinegar. High acid foods can be safely processed using the boiling water method.

Although fruits and tomatoes can be safely processed using the boiling water method, both can be acceptably canned using the pressure canning method. Always follow the processing method stated in the recipe.

Current Presto® Pressure Canners function as both a pressure canner and a boiling water canner providing complete versatility and easy storage.


Preplanning
Prior to the canning season thoroughly examine your pressure canner. Whether you have a new canner or a trusted old canner, it’s important to do a trial run with water to ensure it is functioning acceptably. As a general rule, replace the sealing ring and over-pressure plug every two to three years. If your canner has a dial gauge, we recommend having it tested at your county extension office or with the manufacturer to ensure its proper operation. Finding a problem when there is a load of vegetables in the canner can be disheartening and wasteful.


Always use reliable sources that offer current, research-tested procedures, recipes, and timetables. Such information is available on this Presto website. The National Center for Home Food Preservation and your local Cooperative Extension Service are also reliable sources of home canning information and established processing procedures. Though recipes that have been handed down through the years may hold sentimental value, they are oftentimes unreliable and usually do not include scientifically tested processing procedures that are vital to a successful and safe canning project. Canning information published prior to 1994 may be incorrect and could pose a serious health risk.


Before you begin

Assemble all ingredients, supplies, and equipment needed for your canning project. Carefully read, understand, and follow the recipe and canning instructions as directed. Do not substitute or omit ingredients. Always follow specific manufacturer’s instructions.
Selecting Jars
Glass home cannng jars, sometimes referred to as Mason jars, are made of heat-tempered glass for durability and reuse. These are the only jars recommended for safe home canning. They are available in standard sizes (half-pint, pint and quart jars) and will withstand the heat of a pressure canner, time after time. Note: Half gallon jars are recommended only for canning clear juices, such as grape and apple.

Glass home canning jars offer a deep neck and wide sealing surface to assure a tight seal. Always visually examine canning jars for nicks or cracks. Recycle or discard any damaged jars. Do not use jars from commercially prepared foods because they were made for single-use only. Always use the jar size and exact processing procedures indicated in the research-tested processing recipe.

Preparing Jars for Canning
Jars should be thoroughly washed in hot, sudsy water. Do not use wire brushes, abrasive materials, or cleansers because they may damage the glass. Rinse jars completely with hot water. To help prevent jar breakage, allow jars to stand in very hot water prior to filling with food. A dishwasher may also be used. Wash and dry jars using a regular cycle. When cycle is complete, remove one jar at a time, keeping the rest of the jars heated until needed.

Foods that will be processed less than 10 minutes using the boiling water method, such as with jams and jellies, will need to be placed in jars that have been sterilized. To sterilize the jars, boil them for 10 minutes. If you live at an altitude of 1,000 feet or more, boil an additional minute for each 1,000-foot increase in altitude. However, if you wish, rather than sterilizing jars, the processing time can be increased to 10 minutes for those jams and jellies that have a processing time of 5 minutes. The additional processing time is not harmful to most gels. Keep in mind that if your altitude is above 1,000 feet the processing time needs adjustment. Foods processed 10 minutes or more using the boiling water method or in a pressure canner do not need to be placed in sterilized jars.

Canning Lids and Bands

The two-piece vacuum cap (lid and band) is the recommended closure for home canning. It consists of a flat metal lid with a rubber-like seal on the underside and a threaded metal screw band that secures the lid during processing. The bands can be used repeatedly if they remain in good condition; however, new lids must be used each time. Always prepare lids and bands according to manufacturer's instructions.

Avoid closures such as zinc caps and glass lids that require a jar rubber. These closures do not provide a proper method to determine if the seal is safe. Also, avoid commercial one-piece caps even if they have a rubber-like gasket because they are intended for one-time use only.

Selecting and Preparing Food
Select only produce that is at its peak quality. Produce that is over-ripe or damaged will not be a good canned product. Always follow exact preparation instructions such as peeling, slicing, chopping, puréeing. Altering the recipe may affect the heat penetration of the food which when canned may result in underprocessing.

There are two methods of packing food into jars: raw pack and hot pack. Recipes will indicate a packing method that is best for the food being canned. In some cases, both raw and hot pack are acceptable methods and both will be listed.


Raw Pack: Unheated food is put directly into the jars and then covered with boiling water, juice or syrup. When using the raw pack method most food should be packed tightly in the jars because it will shrink during processing. However, corn, lima beans, peas, and potatoes expand during processing and should be packed loosely. The raw pack method is generally used on foods that become delicate or difficult to handle when cooked.
Hot Pack: Food is cooked or heated to boiling before packing into jars. The food is then covered with the boiling liquid. Foods that are hot packed should be put into the jars loosely because shrinkage will not occur during processing. The hot pack method is generally used on firm, easy-to-handle foods. In many cases, precooking the food may allow it to conform to the jar better for a tighter, more efficient fit. The hot pack method is preferred for most vegetables and fruits, as well as meat, poultry and seafood.

Measuring Headspace
All recipes will indicate the amount of headspace necessary for the food being canned. Headspace is the air space between the top of the food or its liquid and the lid. Leaving too much headspace can result in under processing because it may take too long to release the air from the jar. Leaving too little headspace will trap food between the jar and the lid and may result in an inadequate seal. As a general rule, allow 1/2-inch headspace for fruits and tomatoes and 1-inch for vegetables, meats, poultry, and seafood.

Removing Air Bubbles
After food has been packed in jars, work quickly to remove air bubbles that have become trapped between pieces of food by moving a clean, nonmetallic spatula around the jar between the food and side of the jar. The use of metal utensils can damage canning jars and should be avoided.

Preparing Jar Rims and Adjusting Lids
Immediately wipe jar rims with a clean, damp cloth to remove any residue. Apply hot, flat lid on rim of jar making sure sealing compound is touching glass. Place a band over the lid and screw onto the jar just until resistance is met. Not too tight, as air must release from the jars during processing and cooling. When all the air is released, a vacuum is formed and the lid seals.

The Canning Process
Without delay, process prepared jars of food according to the exact canner manufacturer’s instructions and recipe directions. When processing time is complete, and if using the pressure canning method all pressure in the canner has been released and canner has cooled for 10 minutes, carefully open cover and remove jars from canner with a jar lifter. Place jars on a dry towel on countertop away from drafts leaving 1 to 2 inches of space between jars to allow for even cooling. Do not invert jars or cover with a cloth. Allow jars to cool naturally to room temperature. Allow the jars to completely cool for 12 to 24 hours before checking the seals. It is important to test the seals to be sure a vacuum has been formed. Press down on the center of the lid. If it is concave, or stays down when pressed, the jar is properly vacuum sealed. See frequently asked questions if a jar fails to seal or if you have any other canning questions.


Storing Canned Food
Remove bands. Wipe off any food residue from lids and jars. Do not replace bands as they may rust and become difficult to remove. Store canned food in a cool, dark, and dry place, between 50° and 70°F. Home canned food can be kept for many years. However, after one year the quality will begin to deteriorate. For this reason, always date and label jars before storing.

Detecting Spoilage
If up-to-date instructions and processing times and pressures are followed carefully, spoilage is uncommon. However, it is still recommended to check for signs of spoilage before tasting any canned food. Check for a broken seal, gassiness when opening, mold, sliminess, cloudiness, or unpleasant odors. If any of these signs are present, discard the food. As a safeguard against using canned low-acid and tomato products which may be affected with spoilage that is not readily detected, boil food 10 minutes for altitudes up to 1,000 feet above sea level. Extend the boiling time by 1 minute for each 1,000 foot increase in altitude. Many times odors that cannot be detected in the cold product will become evident by this method. If, after boiling, food does not smell or look right, discard it without tasting.

Go to: Canning Recipe Index
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