Killer Canning, or How to Avoid Poisoning Anyone

Home canning is all the rage. Eating locally is in, and doing so year-round pretty much requires some kind of food preservation. No one's freezer space is unlimited, and home canning is a great way to preserve the harvest. It seems every food blogger is canning and offering recipes for the foods she's canned.



Unfortunately I'm seeing a large number of unsafe canning recipes posted on various food, recipe, and local eating blogs, and we aren't talking about just the kind of unsafe canning that gives you a few days of gastrointestinal misery. We're talking serious neurotoxins, botulism, paralysis, and death.



Here are a few key bits of knowledge, useful whether you're canning yourself or are the recipient of a home-canned gift.



Canning Fruits. In general, canned fruits are safe. Almost all fruits (exceptions include bananas, figs, and tomatoes) are high-acid, which means both that spoilage is less likely and that any spoilage is likely to be evident -- you'll see mold, or the jar when opened will have an off smell, or the seal will be broken. This is why so much home canning is about jams, jellies, marmalades, and other fruit spreads. HIgh-acid fruits are all safe to can in a boiling-water bath using a wide variety of recipes.



Canning Vegetables. This is where the serious food-safety issue comes in. All vegetables are low-acid foods and are unsafe to can in a boiling water bath unless sufficient high-acid ingredients, generally in the form of vinegar, bottled lemon juice, or citric acid, are added. The proportion of high-acid to low-acid ingredients must not be altered from that specified in the recipe. The problem is that often an experienced-cook-but-inexperienced-canner picks up a canning recipe and assumes her cooking experience can be used to adapt and improve the canning recipe. It can't.



Tested Recipes for Canning Vegetables. Unlike cooking recipes, which the cook can adapt to her own tastes -- increasing the proportion of one ingredient, omitting another entirely, using an unspecified technique such as sauteeing the veggies -- the canning of vegetables should be done using a tested recipe (that is, a recipe that has been tested by the USDA -- or the equivalent, in other countries -- and found to be safe for home canning) with no changes in the proportion of high-acid to low-acid foods. To be sure the recipe you are using is a tested recipe, use a trusted resource such as the Ball Blue Book (use a new edition, as canning recommendations have changed over the years), the Ball Complete Book of Home Preserving , the Complete Book of Small-Batch Preserving, or the National Center for Home Food Preservation.



When you discover a delicious-sounding boiling-water bath canning recipe online and think you'd like to try it, ask the person providing the recipe where he got it. (Most foodies are happy to talk about the source of their recipes and won't take this as an insult if you ask in a way that indicates curiosity rather than mistrust.) If he did not get the recipe from a trusted source, or if he adapted it in any way that changes the proportion of vegetables-to-acids, or if he added oils, fats, or animal products, don't use the recipe. Find another similar recipe from a trusted source and use that instead. The same goes for gifts of home canned vegetables, including combination recipes such as salsas, sauces, chutneys, and relishes. I cannot stress this enough. When canned vegetables go bad, one likely culprit is botulinum, which is the neurotoxin that causes botulism: if it doesn't kill you, it can leave you paralyzed. It is a seriously nasty bacteria and nothing to fool around with. Worse yet, unlike mold, you can't see, smell, or taste botulinum. The seal on the jar may not even be broken.



With the sharp increase in canning by inexperienced canners, we are likely also to see an increase in home canning-related food poisonings. Done properly, home canning is very safe and a great way to preserve the harvest so you can eat locally all year around. But do take the necessary steps to make sure you know what you're doing.



The National Center for Home Food Preservation is a great resource for home canners, new and experienced alike. The recipes posted there are all USDA-tested and approved, and they have a ton of information for home canners -- even a complete home-canning course you can download in pdf form.



Your county extension service is an excellent resource for information about canning. Many are offering canning classes geared to new canners.



Another great resource for canners is the Harvest Forum on GardenWeb. You can search the forum archives to find answers to many questions.



Originally posted at Eat.Drink.Better.