Introduction to Canning
Growing your own fruits and vegetables is one of the most rewarding parts of gardening. However, the “fruits” of your labor can be short-lived if you do not properly preserve your harvest. When the proper methods are used, at-home canning will help preserve your fruits and vegetables for up to one year, allowing you to feed your family nutritious, home-grown fruits and vegetables year-round. Canning also allows you to save a significant amount of money on your yearly groceries. Even if you buy your produce from a farmers market or grocery store rather than growing it yourself, in-season fresh produce will be better quality and less expensive than purchasing the same produce in the off-season.
While methods vary, the basic canning process includes preparing the produce, packing it into cans, closing the cans with a canning lid and ring, and heating the cans for a predetermined amount of time. Canning is an effective method of food preservation because it uses high heat to remove destructive microorganisms and create a vacuum seal. Microorganisms include mold, yeast, and bacteria. The vacuum, once sealed, prevents any of these materials from re-entering the can until it is opened (at which point, microorganisms are re-introduced and the food should be prepared and eaten within a few days). There are three basic principles that must be followed when you preserve fruits and vegetables using home canning.
Basic Principles of Canning
- Start with high quality produce.
- Always follow canning recipes exactly.
- Timing is everything.
Start with high quality produce.
The quality of the food you can will determine its quality when you open the can. Fruits and vegetables should be canned within a day of being harvested. When you are unable to can your produce right away, store it somewhere cool, dry and shaded. Never use fruit or vegetables that have been damaged by bugs, disease, bruising or over-ripening. These factors allow bacteria, mold and yeast that start on the surface to penetrate into the center and multiply, at which point they may not be killed by normal canning methods.
Always follow canning recipes exactly.
The number one concern when canning should be safety. Unlike conventional cooking, canning recipes must be followed exactly to ensure the safety of the food. Canning incorrectly can provide the perfect conditions to produce botulism, a deadly form of food poisoning. For this reason, it is extremely important that you follow canning recipes exactly and do not deviate from them. This means using produce that is in peak condition, slicing, dicing, or peeling the produce according to the recipe, and using the correct canning method (pressure vs. boiling), jar size, and processing time for your altitude.
There are two types of canners: pressure canners and boiling water canners. Boiling water canners can only be used with highly acidic foods. At up to 1,000 feet above sea level, water boils at 212 degrees Fahrenheit, which provides sufficient heat for foods or mixtures that have a pH below 4.6 (acidic foods). For low-acid foods or combinations at or above a pH of 4.6, 212 degrees is not sufficient to kill the bacteria, mold and yeast present. A pressure canner must be used, which will reach a temperature of 240 degrees at a pressure of 10 pounds. Each canning recipe will specify pounds of pressure and time needed.
Since there is less barometric pressure at higher altitudes, water boils at lower temperatures. This is why cooking times are often adjusted for high altitude locations, and why you must incorporate altitude into your canning time calculations. If you live 1,000 feet or less above sea level, standard recipes using a boiling point of 212 degrees Fahrenheit will be correct. If you live more than 1,000 feet above sea level, processing time will be adjusted. The specific adjustments are laid out for you in canning recipes.
The Ball Blue Book® Guide to Preserving (644-3209) is essential to the success of your canning project. It features hundreds of canning, freezing and dehydrating recipes along with tips and practices to make sure your preserving project comes out right every time.
Timing is everything.
When it comes to canning, timing is everything. From when you harvest, to preparing your produce, to heating your canner, to processing each can, timing must be exact and one step must flow seamlessly into the next. For this reason, it is important that you read each recipe carefully before you begin and have all the necessary supplies ready. Only prepare as much produce as you will be able to can at once, and work through a complete canning cycle from start to finish before you start the next cycle.
Now that you know the basics of canning, pick up a copy of the Ball Blue Book Guide to Preserving and find out more about the processes you can use to create delicious, nutritious canned fruit and vegetables for your family.