USDA Guide to Home Canning
Caution: All home-canned foods should be canned according tothe procedures in this Guide. Low-acid and tomato foods not canned according to the recommendations in this publication or according to other USDA-endorsed recommendations presenta risk of botulism. If it is possible that any deviation from the USDA-endorsed methods occurred, to prevent the risk ofbotulism, low-acid and tomato foods should be boiled in asaucepan before consuming even if you detect no signs ofspoilage. At altitudes below 1,000 ft, boil foods for 10 minutes.Add an additional minute of boiling time for each additional 1,000 ft elevation. However, this is not intended to serve as arecommendation for consuming foods known to be significantly underprocessed according to current standards and recommended methods. It is not a guarantee that all possible defects and hazards with non-recommended methods can be overcome by this boiling process. The recommendation is to only can low-acidand tomato foods according to the procedures in this Guide.
Reference to commercial products and services is made with the understanding that no discrimination is intended and no endorsement by the U.S. Department of Agriculture is implied. Clear Jel® and Splenda® are mentioned because they are the only suitable products presently available to the general public for the stated purposes in given products.
Preface
Home canning has changed greatly in the 180 years since it was introduced as a way to preserve food. Scientists have found ways to produce safer, higher quality products. The first part of this publication explains the scientific principles on which canning techniques are based, discusses canning equipment, and describes the proper use of jars and lids. It describes basic canning ingredients and procedures and how to use them to achieve safe, high-quality canned products. Finally, it helps you decide whether or not and how much to can.
The second part of this publication is a series of canning guides for specific foods. These guides offer detailed directions for making sugar syrups; and for canning fruits and fruit products, tomatoes and tomato products, vegetables, red meats, poultry, seafoods, and pickles and relishes. Handy guidelines for choosing the right quantities and quality of raw foods accompany each set of directions for fruits, tomatoes, and vegetables. Most recipes are designed to yield a full canner load of pints or quarts. Finally, processing adjustments for altitudes above sea level are given for each food.
This publication contains many new research-based recommendations for canning safer and better quality food at home. It is an invaluable resource book for persons who are canning food for the first time. Experienced canners will find updated information to help them improve their canning practices.
Research is continually being conducted in areas that affect food preservation recommendations. Make sure your food preservation information is always current with up-to-date tested guidelines.
For Safety’s Sake
Pressure canning is the only recommended method for canning meat, poultry, seafood, and vegetables. The bacterium Clostridium botulinum is destroyed in low-acid foods when they are processed at the correct time and pressure in pressure canners. Using boiling water canners for these foods poses a real risk of botulism poisoning.
If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal. Boiling food 10 minutes at altitudes below 1,000 ft should destroy this poison when it is present. For altitudes at and above 1,000 ft, add 1 additional minute per 1,000 ft additional elevation.
Caution: To prevent the risk of botulism, low-acid and tomato foods not canned according to the recommendations in this publication or according to other USDA-endorsed recommendations should be boiled as above, in a saucepan before consuming, even if you detect no signs of spoilage. This is not intended to serve as a recommendation for consuming foods known to be significantly underprocessed according to current standards and recommended methods. It is not a guarantee that all possible defects and hazards with other methods can be overcome by this boiling process. All low-acid foods canned according to the approved recommendations may be eaten without boiling them when you are sure of all the following:
- Food was processed in a pressure canner.
- Gauge of the pressure canner was accurate.
- Up-to-date researched process times and pressures were used for the size of jar, style of
- pack, and kind of food being canned.
- The process time and pressure recommended for sterilizing the food at your altitude was
- followed.
- Jar lid is firmly sealed and concave.
- Nothing has leaked from jar.
- No liquid spurts out when jar is opened.
- No unnatural or “off ” odors can be detected.
Do Your Canned Foods Pass This Test?
Overall appearance
- Good proportion of solid to liquid
- Full pack with proper headspace
- Liquid just covering solid
- Free of air bubbles
- Free of imperfections—stems, cores, seeds
- Good seals
- Practical pack that is done quickly and easily
Fruit and vegetables
- Pieces uniform in size and shape
- Characteristic, uniform color
- Shape retained—not broken or mushy
- Proper maturity
Liquid or syrup
- Clear and free from sediment
Determining Your Altitude Above Sea Level
It is important to know your approximate elevation or altitude above sea level in order to determine a safe processing time for canned foods. Since the boiling temperature of liquid is lower at higher elevations, it is critical that additional time be given for the safe processing of foods at altitudes above sea level.
It is not practical to include a list of altitudes in this guide, since there is wide variation within a State and even a county. For example, the State of Kansas has areas with altitudes varying between 75 ft to 4,039 ft above sea level. Kansas is not generally thought to have high altitudes, but there are many areas of the State where adjustments for altitude must be considered. Colorado, on the other hand, has people living in areas between 3,000 and 10,000 ft above sea level. They tend to be more conscious of the need to make altitude adjustments in the various processing schedules. To list altitudes for specific counties may actually be misleading, due to the differences in geographic terrain within a county.
If you are unsure about the altitude where you will be canning foods, consult your county Extension agent. An alternative source of information would be your local district conservationist with the Soil Conservation Service.