What do I mean when I say that you should adjust your recipe for elevation?
Most canning recipes are formulated by/written for people living at/near sea level … because–quite simply–a large percentage of the people on this planet live below 1,000 feet in elevation. In fact, census data indicates that a solid third of the population of this planet lives below 100 meters … a mere 328 feet above sea level. And–when they write a recipe–they assume everyone else does, too.
However, if you live in a place that sits more than about 1,000 feet above sea level … then you will need to make an adjustment in your canning–both in boiling water bath canning and/or pressure canning–in order to compensate for the fact that you live on higher ground.
Why do you have to adjust your canning?
Water boils at 212.15 degrees at sea level. However, the higher you go elevation-wise … the lower the boiling point of water goes. For example, on the top of Mt. Rainer–a dormant volcano in Washington State and, at a stately 14,410 feet, the highest point in the lower 48-states–water boils at somewhere around 188 degrees. That 24-degree difference is significant when you’re talking about killing canning cooties … even though–let’s be honest–most of us don’t do our canning on top of a mountain. However, even a difference of as little as two or even three degrees can have an undesirable affect on your ability to kill bacteria, yeast spores, molds and more in a canning environment. Some canning cooties can easily withstand temperatures below 212.15 degrees. It takes a hard 212+ degree boil–held for a certain duration … which is also important–in order kill those cooties properly. In fact, 188 degrees–or, in some cases, even 211.5 degrees–is just a nice warm soak in a hot tub for some of the worst canning cooties of the lot. All it does is get them all relaxed and warmed up to go multiply later.
That means … if your water boils at a lower temperature–and boiling is the highest level of water temperature you can achieve at that elevation without something (like a pressure canner) involved to increase the pressure and the temperature–then when you’re using a BWB at higher elevations, it takes a lot more duration during the BWB canning cycle to accomplish the same level of sterilization. You can’t make the water boil hotter in a BWB… so you have to make sure it boils longer in order to make it work properly.
NOTE: This ONLY works when you’re canning properly-acidified, BWB-approved foods at higher elevations. No matter what your elevation is, you should NEVER try to can low-acid foods like meat and vegetable in a BWB, thinking “I know they -say- to use a pressure canner, but I’ll just boil it longer. That should work.”
As I said above, adding to the duration won’t work with foods that are supposed to be pressure-canned. You could attempt to BWB steak chunks or chicken breasts for three full days straight, 24-hours a day without interruption … and STILL not get them completely sterile inside the jar. Duration is not a cure for all of your canning woes. Adding that extra time only works on recipes that are already approved for BWB canning at sea-level–i.e.: high-acid recipes–and it only works to adjust for elevation.
Technically, though … it’s not the elevation. It’s actually the barometric pressure that makes the real difference in all this. However, the two coincide … as you can see from the chart below. The higher the elevation (expressed in the chart below in feet) goes … the lower the barometric pressure (expressed in inches Hg.) goes … and the lower the barometric pressure goes … the lower the temperature where water boils (expressed in degrees Fahrenheit) goes. Inversely, the lower the elevation goes, the higher the barometric pressure goes, and the higher the temperature where water boils.
You get the picture
So how does all that science stuff translate–specifically–into canning?
There are quite a few different answers to that question, and they each depend on what we’re canning right that moment. It can be somewhat confusing at times … especially when you’re trying to can something that doesn’t have an official NCHFP-APPROVED recipe. Granted, it’s not quite rocket science, but it does involve being able to think about several different factors when you’re working between or outside of the various “official” sources.
What I’m going to try to do in the following (extremely long-winded) sections is give you an idea–by category–of how to adjust a recipe for elevation. In addition, I’m going to try to give you some ideas about what to look for/consider when you’re trying to shape and mold a recipe that you either created yourself, or got from somewhere–online/from a book/passed down from a friend or relative–other than on the NCHFP website itself … into something that might actually work in a canning jar … without getting you and half your family sick in the process. Some canning-specific cookbooks and how-tos (like the Ball Complete Book of Home Preserving and others) provide you with altitude charts for their recipes as well … but, sometimes … you’re all on your own. There are a lot of other factors you need to think about along the way, too … but it’s not as confused and difficult as it can seem at first glance.
These are good skills to possess, too. Why? Because we have access to a wealth of recipes online, plus there are thousands and hundreds of thousands of cookbooks in print these days, but–in comparison–only a tiny percentage of them include canning instructions. Sometimes it’s just an oversight. Take me, for example. I’m an avid canner, so–on my own blog–I always try to remember to give you a direct link–where applicable–to the page on the NCHFP website that covers the food I’m talking about canning … but I know I forget at times. Other people don’t even bother. And then–last, but certainly not least … the most dangerous category–some people promote canning methods and timing that are just WRONG! Knowledge is powerful in those cases. It’s important for you to know how to judge a recipe.
If I don’t give you a link to the NCHFP here in a canning post (just a number of minutes, maybe a pressure, and a reminder to adjust for your elevation) or if you’re looking at one of the other eight-million recipes available online, many that give you less than that … but even the ones that seem to give you good canning times and/or pressures–always check the NCHFP first, regardless! It only takes a second to be sure. Double check ME and MY recommendations, too … each and every time … right along with everyone else … just to be sure. PLEASE DO! I try to be accurate, but–just like everyone else–I’m not perfect. I can make mistakes, too. And you won’t offend me at all by double checking to be sure I didn’t transpose digits … or just have a total brain spasm the day I wrote the post. And–if I did–let me know, and I’ll fix it here … with a note of gratitude to you on the post as well
When it comes to other people’s recipes, I know my experience isn’t unique. I’ve seen plenty of so-called ‘safe canning’ recipes online that–when you compare their processing recommendations with the NFHCP’s recommendations for that same type of food/combination of food–they are WAY OFF!! Sure, you can find some good ones on the web, but a large percentage of them are wrong … and 100% of the ones that are wrong suggest that you process your food for less time/heat than the NCHFP recommends. I’ve rarely found a recipe online that suggested more canning time than the NCHFP recommends. For some strange reason (or perhaps not so strange … people are–as a group–impatient) they are ALWAYS trying to cut the time recommended the canning authorities! And the way they go about it–in some cases–is pretty scary. I’ve done a lot of recipe surfing myself, and I’d say that at least 20% of the recipes I find online that include canning instructions are WRONG when compared to the NCHFP’s recommendations for that type of food.
Sure, the NCHFP doesn’t have instructions for everything you could ever want to can on their site/in their booklets. Their budget has always been lacking, and their recipes haven’t had a face-lift since the big salsa craze of the 80s. Regardless, though, they should always be your first stop. They cover canning a lot of solo foods, so–if it’s something as simple as berries in syrup or green beans or chunks of beef stew meat–there’s no need to look further: the NCHFP has you covered … with specific processing methods/times, expressed at a wide variety of elevations.
If you don’t find that specific item listed, or if someone’s giving you information on a recipe they’ve created themselves, based on something you can’t find at the NCHFP … especially not in their list of banned foods … then you’ll need to do a little calculation on your own.
How do I calculate that sort of thing? I don’t even know where to start!
The first thing you need to do is know your elevation. That’s much easier these days than it once was … thanks to websites like Earthtools.org. There, you can use their maps to drill down on your exact house–heck, if you live in one of their heavy coverage zones, you can drill down to your exact KITCHEN–so that you can know the exact elevation at your location.
Once you have your elevation in hand, you’ll notice that there’s a lot of variety in the NCHFP recommendations when it comes to that aspect of canning. For example, many BWB recipes break their processing times down into four zones ….
- Zone 1 is under 1,000 feet.
- Zone 2 is 1,001 ft-to-3,000 ft.
- Zone 3 is 3,001 ft-to-6,ooo ft.
- Zone 4 is over 6,000 ft.
… but not all of them follow that same format … and then pressure canner recommendations can be different as well … so–again–you really need to check the NCHFP website before you start. Never assume that one size fits all, since–just like in women’s clothes–there is no such thing when it comes to canning.
From there, let’s look at the individual categories of foods we seek to preserve, and their individual characteristics when it comes to canning them safely:
And … last, but certainly not least …
Let’s start with the first one, shall we?