By Chef D | Published 8/19/2011
So you’ve considered home canning. There are lots of good reasons for home canning – from avoiding chemical preservatives, to creating homemade gifts, to making it a part of your survival plan.
Before embarking on this endeavor, it is important to know how to do it safely. Our concern with food is that we’re not the only ones that need it. There is a multitude of bacteria and fungi living on our kitchen surfaces, in the air that we breathe, and yes, in our food. In small amounts, most of these bacteria and fungi are not harmful but when we’re putting our food into glass jars and setting them on the shelf, we’re giving these little guys one of their primary needs: time. Time to breed. Time to digest and pass their waste back into our food. So our fundamental task, when canning, is to make sure these little creatures are good and dead before we put that lid on.
Perhaps your grandmother canned. Or your great-grandmother. They probably never hear the words “food microbiology”. This is the study of microorganisms that share our food and how they can result in various food-borne illnesses. If our great canning ancestors had had access to the information we have today we would not be educating people now about the dangerous canning methods of yesteryear such as simply ladling hot food in the jar and then turning the jars upside down to create a seal. Or putting filled jars in the dishwasher to heat them. Yes, the cooling will create a seal but just sealing something doesn’t make it germ-free. Botulism is a rare but deadly disease that is primarily contracted through home-canned goods but fortunately is avoidable.
In part, to understand how to can food safely, we need to understand the life of the microorganism. These guys aren’t very smart, and they’re not very demanding. Besides food and water (moisture), they only really need 3 things to get their party started. First, an environment with low acidity. You’re not going to want to hang out in a jacuzzi tub full of acid, and neither are they. Second and and third, time and temperature. Warm cozy temperatures and plenty of time for them to breed, eat, digest, and pass their waste back into our food. Luckily, we can control these last three things. Food-borne illnesses are largely preventable with a little knowledge and following the directions.
There are two types of canners: water bath canners and pressure canners. Water bath canners are safe to use only if the items being canned are high in acidity. Botulism can survive well in low-acidity environments and is only killed in temperatures exceeding 250F. Water bath canners only heat a jar’s contents to about 210F. Therefore water bath canners have limited uses, primarily for canning fruit, pie fillings and jams which are highly acidic as it will kill of other bacteria, molds and yeasts (as well as halt the enzyme action of fruit which contributes to spoilage). Please note that many old recipes did not take food safety into account the way it is now and are no longer considered safe. Many new recipes add acids such as lemon juice or vinegar to increase acidity.
Canning: Step 2, The Equipment
By Chef D | Published 8/19/2011
Now that we’ve gotten the not so fun task of talking bacteria out of the way, it’s time to roll up our sleeves and start our investigation into the different types of canners out there, and which one we should plunk our money down on.
As discussed above, there are two types of canners: water bath and pressure canners. Actually, there are three if we include the steam canner. However at this time the USDA does not recommend this method as they have not conducted enough research as to its safety. Until the steam method is judged safe, I prefer not to spend time looking into them.
Water bath canners have limited uses as the food item must be acidic enough to stop the growth of the Botulism bacteria as it will not be killed from the lower temperature of approximately 210F that we can hope to reach. But if our goal is to stick to fruits, pie fillings, and jams, then a water bath canner can work just fine and might be a good way to start to determine if it’s something you’re going to find worthwhile.
Examples of high-acid foods (pH less than 4.6) that we can safely processing the water-bath method include fruits such as Apples, Applesauce, Apricots, Berries, Cherries, Cranberries, Peaches, Pears, Pickles, Pickled Beets, Plums, Rhubarb, and acidified Tomatoes as well as Fruit Juices and Tomato Juice. (Just remember, many older recipes were made before we became more knowledgeable about microorganisms and food-borne illnesses and therefore may not be appropriate for safe canning.)
Low-acidic foods would include vegetables and meats. These are NOT safe for the water-canning method.
So let’s take a look at water–bath canners. First, what is the benefit to water-bath canning as opposed to pressure canning? Speed. Jars can be processed in about half the time in a water-bath compared to a pressure canner. To a certain extent, any large metal container can potentially be a water-bath canner. But there are limits. First, it needs to have room for a rack in the bottom that keeps the jars at least ½ inch above the bottom of the pot (you want the water to be able to circulate underneath the jars. It also needs to be deep enough that the jars are covered with 1-2 inches of briskly boiling water. I
Take a look at the stove you will using to boil your jars. If it is an electric range, you’re going to want a flat-bottomed pot. If you have gas, a ridged bottom will be OK but the flat-bottomed will definitely be more versatile. You also don’t want your pot to be a lot larger than the burner as it will not heat the water well if there is a large discrepancy. Also, many canner brands include a disclaimer that they are not meant for flat-top ranges due to the size and weight. This is something to take into account too… for those of you with flat top ranges, you may want to pick something of a smaller size though it means you can do fewer cans at a time.
Choosing a stainless steel brand has the benefit of being used as a stock pot or tamale steamer or the like when canning season is over.
Next, we’ll be looking into pressure canners.