Water-Bath Canning

Many of the recipes in this book call for processing jars of pickles or preserves in a large pot of boiling water, called a water bath. This accomplishes two important things: It sterilizes the jar and its contents, killing bacteria, enzymes, molds, and other elements that could cause the food to spoil; and it forces oxygen out of the jars, creating a seal that prevents microorganisms from getting in. In short, it makes the food in the jar shelf stable for long-term storage.

Water-bath canning is safe for preserving high-acid foods, including most fruits, as well as fruits and vegetables to which vinegar or another form of acid has been added—think pickles. High-acid foods contain a pH level of 4.5 or less (the lower the number, the higher the acid level). Heating these foods to the boiling point (212°F) for a prescribed amount of time is enough to destroy or block the growth of deadly microorganisms, including C. botulinum, the bacterium that causes botulism. Low-acid foods such as meat, fish, and vegetables with no added acid need to be processed at a higher temperature—240°F—and must be pressure canned to be made shelf stable (see page 18).

We think of tomatoes as acidic, but in fact their pH levels vary, especially with golden or low-acid varieties. For this reason, you must add acid to tomatoes—either lemon juice or citric acid—in order to safely can them in a water bath. If you have a pressure canner, you can process tomatoes without adding acid.

Water-bath canning is not difficult, but it is important—extremely important—that you follow the specific directions in each recipe, especially as they pertain to processing times. Different foods require different processing times depending on how dense they are, how much acid they contain, and the size of the jar you are using. Be diligent about timing and about following every step.

This method of canning does require some special equipment, but it’s not expensive and is a worthy investment; I bought my canner more than two decades ago and it is still in tip-top shape. You can find basic canning kits at hardware stores, kitchen supply stores, and many supermarkets, where they tend to be stocked seasonally. Here’s what you need:

Canning kettle or large, deep pot with a lid. I bought a speckled black graniteware canning kettle back in the early 1990s and it has held up beautifully. A 12- to 16-quart aluminum or stainless stockpot or other pot of similar size will also work.

Rack. Most canning sets come with a metal one with folding handles. The rack is placed in the bottom of the pot as a platform on which to set the jars. Its job is to hold the jars in place and prevent them from rattling around and chipping. Two excellent alternatives: My friend (and canning maven) Cathy Barrow uses a round stainless steel baking rack, which she says is sturdier; another friend, Marisa McClellan (author of Food in Jars) uses a flexible silicone trivet.

Jars. I use standard Ball glass jars in a variety of sizes for most of my preserves and pickles that require water-bath canning. The jars range in size from 4 ounces (120 ml) to 1 quart (950 ml). I also like to use Bormioli glass jars, which are made in Italy and have an appealing rounded shape. Their sizes don’t quite correspond to American measurements, so they are not quite as practical. Jars can be reused many times, as long as they are not cracked or chipped. Be sure to inspect your jars for nicks or cracks before using.

Lids and rings. Standard Ball jars are capped with a flat metal lid and screw-on band. The lids have a ring of rubber on the underside that sits flush with the rim of the glass jar. The rubber softens while in the boiling-water bath, allowing air to escape, then becomes firm as the processed jar cools, helping to create the seal. Although the screw-on ring (also called a band) that fits over the lid can be reused, the lids themselves can only be used once for canning. After that, the seal is no longer reliable.

Other useful canning tools. Silicone spatulas are great for stirring down bubbling jams and other preserves. I use a ladle to fill jars and a plastic or metal wide-mouth funnel to guide food into the jars without making a mess. A jar lifter, a clamp of sorts, makes easy work of lifting hot jars out of boiling water. The small magnetic wand known as a lid lifter easily fishes lids and rings out of hot water. A bubble remover is a long, flat plastic tool used to dislodge any air bubbles that form in a filled jar. A clean plastic chopstick also does the trick.

Basic instructions for canning with a water-bath canner

1 • Start with clean equipment. Make sure your canner and canning tools have been washed in hot soapy water and thoroughly dried. Spread a clean kitchen towel out on the work surface near the canner; this is where you will set the jars after they have been processed. Fill the canner about halfway with water and bring to a boil. The level of water will rise once you add your filled jars.

2 • Sterilize your jars and rings. Sterilizing is only necessary if your processing time is less than 10 minutes. Jars processed for 10 minutes or longer will become sterilized while boiling. All the recipes in this book call for processing times of at least 10 minutes. However, I have a long-standing habit of sterilizing all my jars before water-bath canning, so I continue to do it. First, wash jars in hot soapy water. Sterilize by immersing them in a covered pot of boiling water for 10 minutes. I use the water in the canning kettle, and then I use the same water (replenished if necessary) to process the jars once filled. (Alternatively, you can place the jars in a 285°F oven for 30 minutes.) Place the rings in a small covered pot of boiling water and boil for 10 minutes, then turn off the heat and leave them in the water. Do not boil the lids, as it could compromise the seal; just add them to the pot of hot water right before filling the jars.

3 • Fill the jars with the hot preserves or pickles. Remove the hot jars from the canner right before filling, dumping any excess water back into the pot. Fit the jars with the funnel and ladle the hot food into them, taking care to leave the amount of headspace—the space between the top of the food and the top of the jar—specified in the recipe. Leaving too much space could prevent the lid from sealing properly; too little might cause food to seep out and also prevent a seal. Gently run the bubble remover or a plastic chopstick around the inside of the jar, moving it up and down, to dislodge any air bubbles.

4 • Carefully wipe the rims of the filled jars with a damp paper towel to remove any drips or spills. Set the lids on top of the jars and screw on the rings, tightening them with your fingers but without too much force—remember that air needs to escape during processing.

5 • Using the jar lifter, set the jars on the rack in the pot of boiling water, making sure they are submerged by 1 to 2 inches. Return the water to a boil and boil the jars for the amount of time specified in the recipe, allowing adjustments for altitude (see step 8).

6 • When time is up, turn off the heat under the canner and let the jars sit until the bubbling stops. Remove the jars with the jar lifter and set them on a clean kitchen towel to cool. Within a few minutes, you should start to hear that satisfying “ping” indicating that the seal has taken, though not all jars will make noise. Let the jars cool for 12 to 24 hours; do not retighten the lids.

7 • When the jars are cool, remove the rings around the lids and test the seal: Press your finger into the center of the lid; it should remain concave and not flex back up. Lift the jar by the edge of the lid. If the lid stays on, you have a good seal. If, however, your jar has not sealed, transfer the contents to a clean or sterilized jar with a new lid and reprocess within 24 hours. Or, if it is a matter of a single unsealed jar, store it in the refrigerator and consume the food within a week.

8 • Inspect your canning equipment regularly for chips, cracks, rust, and general wear. Replace tools as necessary. The National Center for Home Food Preservation (www.nchfp.uga.edu) and Ball Corporation (www.freshpreserving.com) have more information on water-bath canning, including recommended processing times, altitude adjustments, and troubleshooting information.