For the August canjam, I made what I made almost exactly a year ago today: salsa verde. And because I am creature of habit, I’ll say pretty much what I said in last year’s post: there are shockingly few published instructions available for canning tomatillos. Most of these recipes treat tomatillos like tomatoes, adding acid, and they treat salsa verde like regular tomato salsa, adding onions. But here’s the thing. Being a stubborn goat, I don’t like either of these preparations. I like a salsa verde that’s pretty much tomatillos, water, and a jalapeno or poblano pepper or two.
So what is a goat to do? Turn to Twitter, of course. Last year, zoecancan was kind enough to point me to an incredibly helpful article in the peer-reviewed journal Plant Foods for Human Nutrition. Since it’s behind a paywall, I’ve reproduced the abstract below:
Three studies were conducted to evaluate the safety of tomatillos and products containing tomatillos canned by the water-bath processing method. In the first study, plain tomatillos were processed for 25, 37.5, 50 and 62.5 min. In the second study, five tomatillo/onion combinations were prepared while five tomatillo/green chile combinations were prepared in the third study. pH evaluations were conducted to determine safety in all studies using pH 4.2 as the cut-off value. No differences in the pH of plain tomatillos were detected due to processing time. All jars of plain tomatillos had pH values below 4.1. All combinations of tomatillos/onions and tomatillos/green chile containing more than 50% tomatillo had pH values below the 4.2 cut-off value. Results of the three studies indicate (1) acidification of plain tomatillos is probably unnecessary for canning by the water-bath processing method and (2) combinations of acidic tomatillos and low-acid onions or green chile must contain more than 50% tomatillos to have a pH low enough for safe water-bath processing.
So, based on this, I feel pretty comfortable saying that it’s safe to water-bath can this version of salsa verde, or in fact any version of salsa verde where the quantity of tomatillos (by weight) exceeds the combined weight of onions and/or peppers and herbs. The acid safety cut-off is a pH of 4.6, so at 4.1, this is plenty acidic (remember that a lower pH means higher acidity).
For the recipe, along with instructions for water-bath canning (for the scientific), pressure canning (for the conservative), or freezing (for the squeamish), click here. This time, 2 pounds made 4 half-pints. It scales up, so, if you’ve got a bushel full of tomatillos, knock yourself out!