Go to: Pressure Canning Index
Invisible microorganisms are present all around us. Fruits, vegetables, meat, poultry and seafood contain these microorganisms naturally. 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 processing is sufficient to destroy those agents.
Bacteria, however, are not as easily destroyed. The bacteria, Clostridium botulinum produces a spore that makes a poisonous toxin which causes botulism. This spore is not destroyed at 212° F. In addition, bacteria thrive on low acids in the absence of air. Therefore, for a safe food product, low-acid foods need to be processed at 240° F. This temperature can only be achieved with a pressure canner.
Before you begin...
Always use current published instruction and recipe manuals. 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 pressures and times that are vital to a successful and safe canning project. Extensive research has been conducted on canning in recent years. Canning information published prior to 1994 may be incorrect and could pose a serious health risk.
Before you begin, assemble all ingredients and supplies 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.
Do not use jars from commercially prepared foods such as mayonnaise and peanut butter because they were made for single-use only. 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.
Always use the jar size and exact processing time and pressure indicated in the recipe. Research has been conducted using half-pint, pint, and quart jars. Half-gallon jars are not recommended for pressure canning. Glass home canning jars should be thoroughly washed in hot, sudsy water. Do not use wire brushes or abrasive materials 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 canning. 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.
Using bands and lids
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.
Removing Air Bubbles
Storing Canned 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: Pressure Canning Index
site map |
parts & service |
special offers |
instruction manuals | pressure cooking | canning | recipes | company history | proxy/10-K/10-Q |
financial info | inventor info | dealer resources | school program | your account | ordering info |
|WEB ORDERS SHIPPED TO THE CONTINENTAL UNITED STATES ONLY
©2012 National Presto Industries, Inc. All rights reserved. · This site hosted by WEBTEAM.