Why Can't I Can My Own Recipe at Home?
Anyone who publishes home canning recipes gets asked this qestion almost every day. Usually, people don't realize that all of the recipes I publish are closely follow USDA lab-tested recipes and lab-tested standards. I make the recipes easier to follow, add photos, explanatory text, but underlying them all is a set of ingredients, proportions, equipment, process and conditions that were lab tested, specifically for each and every recipe.
So, here's the answer:
Before canning your own recipe, first, ask yourself:
- How would you know your recipe is safe? Do you have a lab tto culture the product for pathogens, or are you planning to test it on yourself, friends and family?
- How long should you process it?
- Is the acidity sufficient to retard growth of pathogens?
- How effective was the heat penetration in the canner throughout the product?
- What type of canner, water bath or pressure canner?
- How could you be sure the botulism spores were destroyed (you can't see them with the naked eye)?
In addition to the acidity of the food and the heat resistance of the microorganism, the time required for sufficient heat to penetrate all parts of the food in the jar must be considered. Heat is transferred from the outside of the jar through the food and thus is affected by:
- The size and shape of the container. Smaller jars heat faster than wider or taller jars. The USDA no longer recommends jars larger than a half gallon, and typically jars must be 1 quart or smaller.
- Amount of liquid. Food containing a large amount of free liquid heats much more quickly than a more solid product.
- Piece size. Smaller pieces of food (corn, peas) heat much more quickly than large chunks.
- Amount of fat. Fat insulates the food and slows heat transfer. Most canning recipes require little or no added fats or oils.
- The type of heating medium being used. Wet steam heats faster than dry air.
The many factors involved make it impossible to estimate the correct processing conditions for any food product. This is especially true for items which are mixtures of food with differing water content, piece size, fat content, or acidity as well as types and numbers of microorganisms present. The establishment of a correct, safe process requires laboratory research by trained scientists.
This is why you should follow only lab-tested recipes from reputable sources, and only make minor variations to ingredients and their proportions.
This is NOT to say you cannot get your recipe tested! You can, but NO ONE, no prerson, no company, no government organization, no non-profit, no university, etc, does it for free!
If you are interested in having your fanmily recipe manufactured and sold commercially, there are companies you can hire to do this testing. See this page for details.
- National Center for Disease Control, Center for Disease Control and Prevention (CDC)
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Foodborne Pathogenic Microorganisms and Natural Toxins Handbook, The Bad Bug Book.
- Clemson University Extension.
- Ohio State university Extension
- Oil Infusions and the Risk of Botulism, Colorado State University Cooperative Extension, Safefood new - Summer 1998 - Vol 2 / No. 4
- "Botulism Linked to Baked Potatoes".
- " Safe Home Canning of Fruits, Vegetables and Meats" - University of Minnesota
For more information on food borne illness, contact your local county Extension Agent (click here to find your county ext agent).
Examples in the news:
Botulism blamed on improper home-canning
February 27, 2009 - The Spokesman-Review, John
Stucke - "A serious case of botulism in Spokane has prompted warnings
from food preservation experts and health officials to follow strict
safety rules when canning vegetables at home. A nurse in her 30s,
along with two children younger than 10, were stricken with the nerve
toxin after eating improperly canned green beans from a backyard
garden. All three were given an antitoxin that was flown to Spokane
from a special storage facility in Seattle. Special precautions must
be taken when canning low-acid foods such as green beans and
asparagus. Since most vegetables don't have enough natural acidity to
kill the bacteria, they must be canned using a pressure canner that
can reach high temperatures. Or, vegetables may be pickled with
enough vinegar to inhibit growth of the bacteria. As a safety
precaution, canned vegetables should be boiled for 11 minutes at
Spokane's elevation before eating. Foods that were not canned
following U.S. Department of Agriculture standards should be thrown
away before opening."
Click here for the full story.
Botulism in garlic with oil / refrigerated without heat processing first
Three people were hospitalized with botulism after eating a chopped garlic-in-oil mix that had been used in a spread for garlic bread in Kingston, New York. The bottled chopped garlic spread relied solely on refrigeration to ensure safety. The FDA has ordered companies to stop making the product. Most of the 10 to 30 outbreaks reported annually in the United States are associated with home canned foods. Occasionally, commercially produced foods have been involved in outbreaks. Source: The Bad Bug Book (US Government publication)