Home Preservation Safety
[Editor's Note: Today, BlogHer kicks off a series on The Practice of Preserving, a monthly examination of how to can and preserve your locally-grown or -bought food at home. Today, Diana Prichard addresses some of the important safety considerations required for healthy preservation, and in future months, she'll talk about everything from what to do with all those tomatoes that ripen at once to how to can meat when you have a surplus. --Genie]
Usually, when I have to start a sentence with, “I didn’t grow up with...”, it’s a pretty good bet it’ll end with me lamenting some perceived short coming in my life at the hands of my mother. As I’ve come to understand however, it works in an entirely different manner with canning. I didn’t grow up with canning in my life and, as it turns out, I’ve been so much better off for it.
It seems everyone else has stories about their mother’s pressure canner exploding in the kitchen, sending tomato sauce across the ceiling, scaring them and making them a Chef Boy-ar-dee devotee for life. Unlike other interesting antidotes from days gone by, fear paralyzes home-canners to be. I know a woman with an entire pantry full of pickles she refuses to eat because they’re the first thing she ever canned and she’s scared. I know women who won’t even touch a pressure canner lest it spontaneously burst with no provocation whatsoever.
Because I didn’t grow up knowing the canning days gone by, however, I don’t have these stories or their accompanying fears to slow me down. My first canner purchase was a pressure canner, and it wasn’t until I was knee-deep in that first harvest season that I realized there were such things as kitchen explosions to worry about at all. And because I was already armed with updated information and guidelines when I did find out about the mishaps that plagued the generations that had come before me, I wasn’t paralyzed in the slightest. When it comes to this shortcoming, I got lucky!
And as 2012’s growing season gets underway and I talk to more and more people about canning this year’s bounty, I’m reminded of just how lucky I am. Whether you’ve dipped your toes into the canning pond before or are planning on trying your hand at it the first time, here are some safety tips to get started.
Tools & Equipment—Though home canners have traditionally reused store-bought mayonaise and spaghetti sauce jars and while thirft stores can be an affordable source of canning equipment, the reuse of commercial jars for canning isn’t recommended, and older canning equipment may be in need of updating. Instead, it’s a good idea to use tools that have been made for home canning and to always double-check all equipment to make sure it’s in good repair.
For jars, this means looking them over for hairline cracks and running your finger around the rim of the jar to feel for bumps, chips and imperfections that might otherwise compromise your seal. When in doubt, it’s better to set aside a jar for uses other than canning, than to end up with siphoning out a canner full of food due to a busted jar.
For equipment, such as used canners, this means having the guages calibrated at your local extension office, and replacing old seals and gaskets when they show signs of wear such as becoming brittle.
Low v. High Acid Foods—The acid content of foods help determine the safest way to process them. The pH in high-acid foods helps hinder growth of pathogens that could cause illness, so they often require less intensive processing times and temperatures. The pH of low acid foods however, create an environment where dangerous nasties such as botulism may thrive. These foods usually need to be pressure canned, rather than just water-bath canned. When recipes call for a mix of high- and low-acid foods, the general rule of thumb is to process under the guidelines for the ingredient requiring the highest temperature (or pressure) and longest amount of time.
Density & Recipes—Acid isn't the only deciding factor for how to best preserve food, howeverdensity also plays an important role. Some foods, like pureed pumpkin, are so dense even the highest pressure achieved with home canning equipment cannot penetrate to the center of the jars. These foods are not recommended for home canning at all. Usually, alternate recipes are available though. For pumpkin, for instance, simply cubing it, rather than pureeing, makes all the difference.
Know Your Altitude—Most canning recipes are written for preserving at low altitudes (up to 1,000 feet above sea level). Because the boiling point of water changes at higher altitudes, adjustments must be made when home canning at heights above 1,000 feet. Most reputable canning guide books, such as the Ball Guide to Home Preserving, contain charts to help determine the temperatures and times at which to preserve foods at high altitudes.
Want to know more? The National Center for Home Food Preservation has a very handy beginners guide.
Until next time, here’s to not hiding under the kitchen table as the pressure rises on the first batch of green beans this season!