After spending the summer eating the harvest of your backyard vegetable garden, it may be hard to go back to buying your veggies from the grocery store. Store-bought produce tends to be less flavorful—and more pricey. Just like with your fruit harvest, thanks to canning, you can continue enjoying the fruits—er, vegetables—of your labor and even save money!
However, unlike fruit, vegetables have a low acidic makeup and cannot be safely canned using a water bath canner—unless you’re pickling them instead (See section on pickling below). When canning fruit, the natural acids in fruit and the temperature of the boiling water helps kill any bacteria that may have gotten into the jars, making them free from contamination (See more on Step By Step Canning of High Acid Foods from our friends at Ball Corp.) . But, without those natural acids boiling water does not get hot enough to kill the bacteria Clostridium botulinum. So, the safest way to preserve your homegrown veggies is to use a pressure canner. The pressure canner can get much hotter than the water bath.
“I grow my own vegetables and herbs. I like being able to tell people that
the lunch I’m serving started out as a seed in my yard.”
Curtis Stone, Australian chef and author
A pressure canner does not fully submerge the jars like a water bath canner would, but instead uses heat to press the air out. The rising heat of the water raises the temperature in the jars until all the air has escaped and any bacteria have been killed. At this point, the jars will have sealed themselves shut. A pressure canner typically takes 10 to 15 minutes to seal jars. Depending on its size, the canner will need to cool for 30 to 60 minutes before you slowly open it. (See more on Step By Step Canning of Low Acid Foods from Ball Corp.) Speeding up the cooling process or opening the lid too soon can be dangerous if the pressure hasn’t had a chance to dissipate. Follow your manufacturer’s instructions.
Speaking of safety concerns, it is a good practice to check your pressure canner’s gauge once a year for accuracy. The best place to get this done is through you county extension office. (To find your local office check http://www.csrees.usda.gov/Extension/.) There may be a small fee to check your gauge.
In addition, always read the guidelines that come with your canner so you’re aware of the cooking time variations that occur depending on the altitude where you live. After the jars have been processed and cooled, check to see if they are sealed properly by pressing on the center of the lid with your finger. If it moves, the jar did not seal properly and is at risk for contamination.
What is pickling? According to Wikipedia, pickling (also known as “brining” or “corning”) is the process of preserving food by marinating and storing it in an acid solution, usually vinegar. The resulting food is called a pickle. This procedure gives the food a salty or sour taste. Another distinguishing characteristic is a pH of less than 4.6, which is sufficient to kill most bacteria. Pickling can preserve perishable foods for months.
Pickling is often used for fruits, eggs, or vegetables. Because vegetables are preserved in an acidic liquid, it is okay to use a water bath canner. The acidity of the vinegar is high enough to kill any bacteria the temperature of the boiling water cannot kill.
Water bath canners need to be large enough for your jars and have a tight-fitting lid. You will also need a wire rack to sit inside the canner to hold the jars in place so you can remove them without scalding your hands. If you’re using pint-sized jars, you will want a container that is 10 inches deep; for quart sized-jars, look for one that is 12 inches deep. Fill the canner so that the water is 4 to 5 inches deeper than the height of the jars. The temperature of the water and the length of time the jars are in the canner will depend on the recipe and whether you are raw- or hot-packing the jars.
Select fresh, young, tender vegetables from your garden. For best results, can them within three hours of harvesting. Vegetables can be prepared for canning two ways:
Aside from pickling, many people like to can their vegetables for sauces, soups, or chilis. Using extra care is recommended, since the ingredients in soups all have varying levels of acidity and are heat-processed at different rates. To be safe, when canning these items, always use a pressure canner and the hot-pack method.
The U.S. Department of Agriculture also advises to never include noodles, rice, flour, dairy products, or thickeners before canning. These ingredients can all be added later when you heat up the recipe.