It’s August and that means that for those of you participating in the Mastery Challenge (and remember, you can opt in or out each month), it’s time to try out a new skill. This time around, we’ve got two skill options to choose from. You can either try Low Temperature Pasteurization or Steam Canning (or both). Let’s split them apart and dig into each technique individually.
What is Low Temperature Pasteurization?
Low Temperature Pasteurization (LTP) is a process in which you simmer jars of pickles in water that’s between 180 and 185 degrees F rather than process them in a boiling water bath. You do this for a longer period of time (typically 25-30 minutes). The longer, lower temperature allows you to kill off bacteria while retaining a firmer finished texture.
This technique is used primarily for pickles, as a way to retain a crunchier, firmer texture (though don’t get too excited. They still soften a little. But it’s better than pickles from a boiling water bath canner). The pickles are prepared just as you would for a boiling water bath process and are fully submerged in water for best heat penetration.
The trickiest bit of LTP is maintaining the proper temperature. I like to use an immersion circulator (as described in this post from last fall), but a reliable stovetop or portable induction burner will also do the trick. Just make sure to have a good digital candy thermometer that can clip onto the pot on hand to keep tabs on the temperature.
Currently, this process has only been tested on cucumber pickles, but adventurous canners might also try it on hot peppers (similar pH to cucumbers) or green tomatoes (lower pH) to create more textural finished pickles.
For more on this process, I recommend reading this piece on Healthy Canning and this one on The Babbling Botanist.
What is Steam Canning?
Before we dig in, let’s address the elephant in the room. Some of you might be thinking, “hey, isn’t steam canning a prohibited technique?” Well, for the longest time, steam canning wasn’t a process that was recommended by canning experts. This wasn’t because it was necessarily unsafe, but instead because there wasn’t funding available to do the research necessary to determine its safety. However, thanks to research done at the University of Wisconsin, it has been determined that it is now safe to use under certain circumstances.
Steam canning (also sometimes known as atmospheric steam canning so as to differentiate it from pressure canning, which also uses steam), is a process in which jars are enclosed in a large pot that contains a few inches of water and is in possession of a tight-fitting lid. The water is brought to a boil, which produces steam. The steam reaches 212 degrees F (same as the water would), and the jars are duly processed.
You typically see two different kinds of steam canners. There are those that look like old-fashioned cake tins, with a shallow base and a large domed lid. The second type looks like a traditional boiling water bath, but has a rack designed to elevate the jars and a thermometer in the handle, allowing you to see when the interior of the pot has achieved the proper temperature.
The benefits of steam canning are that you don’t need to use as much water (great for drought-stricken areas), you don’t need to keep your burner at full blast (once you’ve built up a head of steam, you don’t need as much heat to maintain it), and because you’re working with less water, it takes less time and energy to reach the proper temperature.
Steam canning can be used for any high acid preserve, provided it is processed for 45 minutes or less. Any longer and you run the risk of boiling the water reservoir dry, which isn’t good for your preserve or your cookware.
For more on steam canning, read this piece from the University of Wisconsin Extension, this article from Healthy Canning, and this one from canning doyenne Linda Ziedrich.
I’m not going to recommend recipes this month, because the field is pretty wide open. You can do a small assortment of pickles with LTP and an almost endless array of recipes with steam canning. Try applying one of these techniques to an old favorite, or test drive them with something new and delicious. The choice is yours!
To be included in the monthly stats and round-up, please submit your finished project by Wednesday, August 30 using this form.
Would LTP be safe to use on okra?
Hooray! I’m fermenting pickles as I type and will be trying the low-temp pasteurization method. I’ve been curious how that works and am glad that it may be a better option.
Great post and articles. I have been following low temperature pasteurization ever since I started with sous vide. I have done lots of pickles with excellent results and a garlic confit that will be on my counter from now on. I have a wonderful crop of tomatoes about 3 weeks from harvest. I have seen articles that say 3 hours at 190 is the functional equivalent of 10 minutes of pressure canning. If anyone has insights to share I would love hearing them.
It might be 3 hours at 190 is the functional equivalent of 10 minutes of pressure cooking, but it is mostly certainly not an equivalent for pressure canning. Botulism spores do not die until you expose them to at least 240F. No amount of time simply exposing the food to a lower temperature will do the same.
Marisa, does low-temp pasteurization produce shelf-stable pickles? Or should these be put in the refrigerator? I’ve read a bunch about this, but I’ve never seen the explicitly pointed out. Kind seems like an important point to make.
I just started steam canning this past month and it has changed my life ? I recently attended a Penn State extension event and they are now also on board with steam canning. It has made the whole canning process so much quicker plus I don’t have a heavy pot of water on my flat top stove.
I am assuming that you would still correct for altitude? Would you use the standard addition- example of 10 minutes at 5,500 feet? Would this further soften the pickles?
You don’t have to adjust LTP for altitude. You just have to meet the right temperature for the right duration.