Can Your Tomatoes Carefully

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Pay heed to the new USDA guidelines for preserving tomatoes, and to the author's heartfelt plea:

I canned my first batch of homegrown produce 58 years ago, when I was just nine years old. Countless quart and pint jars later, the tomato remains my favorite garden product to put up . . . mostly because it's my favorite to eat.

I shudder, however, when I think of how many people in this country are innocently using unsafe tomato-canning techniques. For instance, if you are following a canning guide that's more than two years old, you may not be aware that the raw-pack, boiling-water-bath method—commonly used over the past several decades—is no longer considered safe for tomatoes. And I can't even count the number of times I've heard people say—to my horror—that they still can their tomatoes the old-fashioned open-kettle way because "they never hurt my grandmother or my mother, and they won't hurt me."

Granted, botulism poisoning from canned tomatoes is relatively rare—but when you're talking about a disease that destroys human life, rare isn't enough. I have seen the ravages of the deadly Clostridium botulinum. It is an insidious killer, for it reveals no clues to its presence: no mold, no odor, no color or taste change. It will grow and thrive in a perfectly sealed (but insufficiently heated) canning jar.

And although tomatoes are generally considered a high-acid food—one that supposedly presents a hostile environment for botulinum—the fact is that their pH can vary greatly, not only by variety, but by a whole range of other factors. Too-green tomatoes, overripe tomatoes, tomatoes from pulled vines, bruised tomatoes, low-acid-type tomatoes, tomatoes grown in low-acid soil . . . all have been blamed for producing "killer jars."

Finally, after years of debate (and the controversy continues), the U.S. Department of Agriculture has changed its recommendations for canning tomatoes: The USDA has dropped the cold-pack, boiling-water-bath method from its list of approved techniques . . . recommended that an acidifier be added to tomato products (particularly low-acid and very ripe produce) . . . and lengthened its processing-time guidelines for the hot-pack, boiling-water-bath method (see the sidebar below).