water bath canning, racks are placed in stockpots or water bath canners filled with water and the pot is brought to a boil on the stove top. The filled canning jars are placed on these racks and processed (i.e., boiled) for a specific amount of time according to the food being canned. Then the jars are cooled, which is when the lids seal shut. Once the jars have cooled and the seals are tight, rings are added to the jars and the food can be stored away.
The Pressure Canning Method
Pressure canning is done, as the name implies, in either a stove-top or electric pressure canner. These canners come in many sizes, and the one you choose depends primarily on how many jars you want to process at one time. As in water bath canning, metal racks are placed in the pressure canner, the canner is filled with water, and the jars are placed inside. The jars are processed under pressure (dictated by the foods you’re canning) for a certain period of time (also dictated by the food you’re canning) and then removed to cool and seal.
Pressure canning may seem intimidating to beginners, but it’s easy to learn and incredibly rewarding because it allows you to safely can almost any food, including meats, stews, soups, chilies, and other meals.
You can decide which method you would like to start with. Your decision might be based on the equipment you have available, a friend or family member who can lead you through a particular method, or the types of foods that you’re interested in canning. Whichever method you choose to learn first, you may want to borrow the equipment and purchase only a few jars. This way, you can limit your investment until you know for certain that canning is for you. Start out with very simple foods and recipes, such as dill pickles, tomato sauce, or canned peaches, and gradually work your way toward more complex recipes and even trying your own variations. When you’re completely comfortable with both the science and the process of your first method of canning, then you can confidently start learning the other.
Since many people typically choose to start with the water bath method, this book begins with the water bath canning method and water bath recipes.
Note: You can actually process high-acid foods in a pressure canner, but water bath canning is quicker, so the choice is up to you.
Food Acidity and How It Affects Your Processing Method
Whether food should be processed in a water bath canner or a pressure canner depends on the acidity of the food you’re canning. Acidity can be natural, as with many fruits, or it can be added. The term pH is a measure of the acidity in a food; the lower the pH value, the more acid in the food. You can increase the acidity level in foods by adding lemon juice, citric acid, or vinegar.
High-acid foods contain enough acid to block the growth of Clostridium botulinum. High-acid foods have a pH of 4.6 or lower. These include fruits; pickles; jams, jellies and marmalades; fruit butters; and sauerkraut.
Low-acid foods don’t have enough acid to prevent the growth of the Clostridium botulinum bacteria, which is what causes botulism. Low-acid foods need to be heated to protect them. Low-acid foods have natural pH values higher than 4.6. These include meats, seafood, poultry, milk, and fresh vegetables, except for most varieties of tomatoes. When you create a mixture of low-acid and high-acid foods, that mixture also has a pH value above 4.6, unless the recipe also includes enough lemon juice, citric acid, or vinegar to make it a high-acid food. The chart below gives approximate pH levels for popular canning foods. Note that levels may vary with different varieties of the fruits and vegetables listed.
Note: Although tomatoes are generally considered a high-acid food, some of them have pH values slightly above 4.6. You should either add lemon juice or citric acid to these varieties, or use a pressure canner to process them.
Botulinum bacteria are almost impossible to eliminate simply by bringing them to a boiling temperature (212 degrees F). This is why low-acid foods need to be processed at temperatures between 240 and 280 degrees F.
In a pressure canner, this means processing the food at 10 to 15 psi. The abbreviation psi means “pounds per square inch of pressure,” which you measure by using the pressure gauge located on or near the lid of the canner. At temperatures of 240 to 280 degrees F, the bacteria in low-acid canned food can be destroyed in 20 to 100 minutes. The exact time it will take depends on the kind of food you’re canning, the way it is packed, and the size of the jars you’re using. The time needed to safely process low-acid foods in a water bath canner would range between 7 and 11 hours, but the time needed to process high-acid foods using a water bath canner only runs between 5 and 85 minutes.
Processing time using either pressure canning or the water bath method depends on:
• the type of food
• the altitude of your geographic location
• the recipe’s acidity
• the size of the jars
Each of the recipes in this book includes processing times.
Fresh produce from your garden or a farmers’ market is the best choice for canning.
Selecting Produce for Canning
Canning does not make mediocre foods taste more palatable, nor will it rescue food that’s about to spoil. It’s important to be choosy when selecting the foods you’ll be canning; that way, your canned foods will be delicious and safe to eat.
Choose the Best Quality You Can Find
Fresh is best and fresh in season is even better. Canning began as a way to preserve the best flavors of a given season, in addition to putting food up for the non-growing season.
Pick fruits and vegetables that are at their very peak of flavor. This means buying in season as much as possible and locally, if available in your area. Foods picked before they’re ripe and shipped thousands of miles will lack the flavor of locally sourced foods. This means you should be looking for strawberries in June and in the fall, fresh peas in the spring, and so on. Many types of produce have long growing seasons, especially if you live in a more temperate climate, so it’s fairly easy to buy them fresh and flavorful for much of the year. Cucumbers, beans, and tomatoes are good examples.
If you’re not able to grow your own produce, try to purchase foods for canning at a farmers’ market or from a local farmer. Organic produce is always a good choice for canning, and farmers may be willing to give you a price break on the larger quantities for a day of canning.
Inspect Your Produce Carefully Before Processing
If you’re buying your produce by the case, bushel, or bucket, be sure to carefully inspect each piece as you wash it. Discard anything that appears to have mold on it (either green or a thin, white coating near the stem). Also be sure to toss anything that has holes, cuts, or other openings that could be portals for bugs, insect eggs, or bacteria.
Tips to Avoid Spoilage
The last thing you want after carefully growing, choosing, and canning your wonderful foods is to lose some of them to spoilage. More important, you don’t want anyone to become ill from eating spoiled food.
Canning
