Canning has been used for centuries to preserve different foods for later use. This can be a cost-effective way to enjoy fresh fruits and vegetables throughout the year, even when they are out of season. Canning can preserve homemade jams, jellies, pickles, fruits, vegetables, meats, soups and more. Canned food can last for several years, making it a convenient and cost-effective option for home food storage.
Canned food is also convenient for meal planning and emergency preparedness. Having a supply of canned food on hand can help ensure that you always have nutritious food available, even during emergencies or power outages.
Types of Canning
Pressure canning
This method uses a specialized pressure canner to process sealed jars of food at temperatures significantly higher than boiling water. This technique is essential for safely preserving low-acid foods.
The process relies on generating steam under pressure within a sealed canner, which raises the boiling point of water. For Gilbert, Arizona (~2000 ft elevation), operating a pressure canner at 6 lbs per square inch (psi) achieves internal temperatures of approximately 227°F (108°C). This elevated temperature is necessary to destroy heat-resistant bacterial spores, particularly those of Clostridium botulinum, which can produce the deadly toxin responsible for botulism in low-acid environments.
Boiling water / Water bath canning
This method involves submerging sealed jars of food in a large pot of boiling water to process them at 212°F (100°C) at sea level and is a safe method for high-acid foods.
The process relies on the combination of heat from boiling water and the natural or added acidity of the food to destroy spoilage organisms, such as molds, yeasts, and most bacteria. High-acid foods have a pH of 4.6 or below, which inhibits the growth of Clostridium botulinum spores—the bacterium responsible for botulism. These spores survive boiling temperatures but cannot produce toxin in sufficiently acidic environments. In contrast, low-acid foods (pH above 4.6) require pressure canning to achieve higher temperatures (240–250°F) that destroy these spores.
Dry canning
This method is excellent for extending the freshness of dry goods and dehydrated foods when using a vacuum sealer to remove oxygen from the jar, however, dry canning using an oven to heat the jars is NOT true canning and is not a solution for Long-Term food storage. Some of the considerations of dry canning include:
- Inadequate heat penetration and sterilization — Without using liquid, heat transfers unevenly. This can fail to kill bacterial spores leading to a high risk of botulism — a potentially fatal illness.
- Botulism risk — Particularly severe for low-acid foods like vegetables processed without liquid. The USDA and NCHFP explicitly warn that omitting required liquid results in under-processing.
- Spoilage potential — Trapped moisture or uneven heating may cause mold, rancidity (especially in nuts/oily foods), or bacterial growth despite a sealed jar.
The BASIC Process
The basics involves heating food to a high temperature and then sealing it in airtight containers, such as glass jars or metal cans. The process of canning involves several steps:
- Prepare the canning equipment and make sure all pieces are clean.
- Prepare the food by washing, peeling, and cutting it into appropriate sizes.
- Heat the food to a high temperature, either by boiling or steam, to kill any bacteria or microorganisms that may be present. This step is essential to ensure that the food is safe to eat and will not spoil.
- NOTE: For some foods, heating in advance is not necessary. Make sure to follow directions for a specific food in order to prevent spoilage.
- Ladled the food into clean jars or cans, leaving some headspace at the top to allow for expansion during processing. T
- Seal the jars or cans with lids that have been sterilized to prevent contamination.
- Process the sealed containers in a pressure canner or boiling water bath for a specific amount of time, depending on the type of food and altitude. This step helps to create a vacuum seal that prevents air and bacteria from entering the container, ensuring that the food remains fresh and safe to eat.
NOTE: Not all foods are suitable for canning. Some foods, such as dairy products and low-acid vegetables like green beans, require special processing methods to ensure their safety. Research the specific requirements for each food you plan to can and follow trusted recipes and procedures.
Where to get bulk produce and meat
Arizona Fruit Lady
azfruitlady@gmail.com
480-234-5407
Superstition Ranch Market
4755 E Main St, Mesa, 85205
(480) 832-3421
Midwestern Meats
4308 E Main St, Mesa, 85205
(480) 924-5855
Books and Resources
The University of Georgia National Center for Home Food Preservation is an excellent source for information about home canning. Visit he link below for basic information about the principles and process of canning.
National Center for Home Food Preservation
The Complete Book of Home Canning 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. This latest Skyhorse Publishing edition features practical full-color illustrations as well has full-color photos showing the ingredients and techniques described.
With a library card, this book can be borrowed for free through the Libby App.
