When it comes to canning tomatoes and tomato-based products, it gets a little trickier. Modern rules set forth by the NCHFP use acid in most tomato-based recipes … with the exception of their age-old recipe for tomato paste. That turn toward acidification has been a major change in the last few decades … a change that a lot of people haven’t caught up with yet. Therefore, when reviewing a recipe you find online–be it for canned tomato sauce, ketchup, salsa, or whatever–you should always refer to the NCHFP’s collection of recipes for specific recommendations for the various types of tomato products … especially if it’s a BWB product. That’s the best place to start. See how close it compares to something you know is safe … but–as always–we tend to find ourselves with recipes that don’t quite fit into their specific guidelines. When you do, the question is always … how do I judge what I have against what they have? And, of course, how do I adjust it for my elevation?
In a lot of ways, tomatoes are canned just like fruit. That’s because they are a type of fruit. They contain some sugar and some acid–just like fruits–with the actual levels determined by variety, ripeness, and several other factors. Like most agricultural products, the acid and sugar levels vary according to variety, field, moisture content, and a whole lot more. Some of them vary so widely that it could be very confusing trying to can them safely, especially given the changes in the food system in the last 30-40 years.
That’s why the NCHFP developed an acidification process that ensures your tomato products are canned safely, no matter how much they vary individually in chemical composition. According to their recommendation, if you’re canning quarts of tomatoes–whole, halves, diced, crushed, etc.–that are prepared simply, and without much in the way of other produce added to them … then they require additional acid in the form of:
- two tablespoons of bottled lemon juice … or
- four tablespoons of 5% vinegar … or
- 1/2 teaspoon of citric acid per quart
- one tablespoon bottled lemon juice … or
- two tablespoons of 5% vinegar … or
- 1/4 teaspoon citric acid per pint
Once you start straying away from plain tomato products, you can add or subtract dry herbs and spices freely … as always … without it affecting the processing time your product needs. You can also add certain amounts of other–usually savory–vegetables (in salsas, etc.) as long as you acidify the final product enough to cover them. Generally speaking, 1/4 cup of bottled lemon juice added per pint of tomatoes and vegetables is adequate to cover the addition of onions, peppers, and celery … regardless of their proportions to the tomatoes/whole.
However, if you want to add meat or any other vegetable to your tomatoes–such as squash, mushrooms, etc.–that puts them in a whole ‘nother category … one we’ll discuss more coming up.
Just like with fruits, when presented with what looks to be a can-able tomato-based recipe, first check the NCHFP website to see if you can locate a comparable recipe … one that uses the same ingredients in similar amounts. Remember, you can’t compare a tomato onion sauce that calls for one cup of tomatoes and two tablespoons of onions … equally … with a tomato-onion sauce that calls for one cup of tomatoes and three cups of onions. They’re not the same–not at all–especially not when you’re talking about a BWB recipe, where precise combinations, acid-levels, etc. are important to the overall safety of the dish. Adding more of something that’s NOT an acid ingredient (like adding more onions in my two sauce examples above) but still trying to process it in a BWB for the same amount of time as the original recipe is just asking for trouble. All those onions would be throwing off the acid level of your final product … enough that it may make a difference in the safety and longevity of your canned tomato products.
Basically, when it comes to tomato-based products … you either need to find a recipe on the NCHFP site that more closely mirrors the proportions of your recipe … then use its processing information for your recipe … or you need to use the recipes provided by the NCHFP (like their spaghetti sauce with meat recipe) and then add/change the spices and/or cooking method to make it taste more like the recipe you found/the taste you’re trying to achieve. Those are your two best options.
The problem is, though … not all tomato recipes can be wedged into one of those two best options. That’s where it really gets tricky … but a few rules of thumb can help you navigate though it. First and foremost:
1) remember, there are NO safe BWB recipes for tomato-based products that contain meats, period! Dishes that contain meat must ALWAYS be pressure canned.
In addition, there are a LOT of tomato-based dishes out there which feature a wide variety of additional vegetables, over and above the normal sorts of onions, peppers, and celery. The question is, can those vegetables be added to your tomato-based product safely … or not?
The solution is usually pretty simple:
2) when adding other vegetables (in addition to onions, peppers and celery) to your tomato-based foods, first check the NCHFP charts for that vegetable. The rule of thumb is … use the longest processing time among your ingredients. That means that the combination of tomatoes, potatoes, whole-kernel corn, and lima beans should be processed based on the recommendation for the whole kernel corn: 55 minutes for pints, and 85 minutes for quarts.
Also–when in doubt–remember recommended canning times are minimums. You can’t use extra time to make up for everything–especially not for adding banned ingredients into your jar, or for changing the proportions of things drastically … especially if you increase things on the non-acid side of the house–but if you feel like the extra two tablespoons of onions that you added–in addition to the quarter cup the recipe called for–is enough proportionally for it to *maybe* need some extra processing … there’s no rule that says you can’t process it a few more minutes … just to feel like you’re being extra sure. At most, you’re going to lose a little more texture and maybe a bit more of the nutrients … but if it keeps you from a bad case of canning cooties … so be it, right?
The types of tomatoes and tomato-based products that you can can in a boiling water bath include tomato juice, whole/half/quartered/chopped in water/juice/raw-packed, crushed, sauce, ketchup, hot sauce, BBQ sauce, and various acidified salsas. Some of these products can also be safely canned in a pressure canner, and in a much shorter time-frame. Check the various recipes on the NCHFP website to see which ones have both sets of instructions. Usually, they’re the ones where texture isn’t as big an issue.
The types of tomatoes and tomato-based products that you can not can in a boiling water bath include tomatoes mixed with okra, zucchini, and any vegetables other than onions, peppers, and celery; spaghetti sauce (with meat or without) that contains any other vegetables; and any non-acidified tomato-based sauce such as Mexican tomato sauce, etc. These types of products should ALWAYS be pressure canned.
Here’s where tomatoes get kinda tricky. The sorts of tomato recipes that you’re allowed to process in a BWB are very basic for the most part. With the exception of things like ketchup, hot sauce, BBQ sauce and salsas … most of the whole, half, quartered, diced, chopped, crushed, etc.–i.e. the plain tomato recipes–can be processed without a pressure canner … but they should be processed exactly like the NCHFP recommends. There’s very little difference in those sorts of recipes (I mean, how many different ways can you can plain old whole tomatoes … and still call them plain old whole tomatoes?) so I recommend you stick with the classics in those cases, with the actual recipes and processes outlined for each tomato product on the UGA-based site. Those recipes were designed by scientists–and double-checked using laboratory equipment you don’t have in your kitchen–to be repeatable. That means that–when you use that recipe exactly as it’s written–you should get the same results in your kitchen that they got in their lab. They also give specific instructions for adjusting their recipes for your elevation … so why guess when it’s already been done for you?
Beyond that–when you start talking about ketchup, hot sauce, BBQ sauce, and various other acidified tomato-based sauces–you get into the world where recipes vary widely … and wildly. Just like with fruits, if you find a recipe–online or otherwise–where they don’t give you specific canning times/methods … then check it against the tomato recipes offered by the NCHFP. If you find a very similar recipe–one with similar approved BWB ingredients and a similar level of acidification–then you should process and time yours based on theirs, maybe giving it a couple of extra minutes for good measure. Just be sure to maintain good acidification at all times.
If you decide you want to try someone’s so-called tried and true tomato recipe online–a recipe where they give you one BWB processing time, where all of the ingredients are BWB-approved–then you can use the following chart to determine your elevation adjustment.
When it comes to strictly pressure-canned tomato products, the picture is a little different. If you’ll notice on the recipes that require a PC–stewed tomatoes with un-approved vegetables, spaghetti sauce that also contains large amounts of other vegetables and/or meat, and other non-acidified tomato-based sauces–there’s no added acid in any of them … and that’s the big difference here! Without that added acid–and with vegetables and/or meat on board that you cannot safely acidify, regardless–you cannot safely can tomato products in a BWB. You MUST use a pressure canner to assure the long-term safety of your food.
Pressure canning times break out a little different than the BWB times … because–in pressure canning–the times don’t change based on elevation … the pressures do … and a dial-gauge canner’s pressures change differently–and at different levels–than a weight-gauge canner.
Confused yet? I thought so
Don’t be. Chances are … when you’re first learning all of this, you’ll only be using one form of canner. You’ll either have a dial-gauge pressure canner or a weight-gauge pressure canner, based on your personal preferences. If you’re still deciding, you can read my discussion on the operation of pressure canners and pros and cons of each style and brand. Once you have your first canner in hand, then you’ll learn how to operate that particular model … and ignore the instructions for the other form of canner. By the time you’re hooked enough to own both styles–like I do–you’ll be ready to know and easily differentiate between the two.
Weight-gauge canners–my personal favorite–are a lot easier to deal with when it comes to adjusting for your elevation. The tomato-based sauces category is a prime example. There are only two zones, and the cut-off is right at 1,000 feet. If you’re below 1,000 feet in elevation … you use 10psi. If you’re over 1,000 feet in elevation … you use 15 psi. It’s as simple as that.
As you can see from the chart below, dial gauge canners are a bit more involved. Your precise pressure depends on your precise elevation … so this is one of the places where you really do need to know exactly how high you are above sea level. If you don’t know, you can find a great website here called Earth Tools … where you can put a pin in the map on your house, and it will give you latitude, longitude, elevation, and more. It’s how I know I live at 383.9 feet of elevation … so I’m one of the people who isn’t in the dominant third of the population … but I’m still close enough to can in Zone 1 full-time. Technically, I probably can at 384.5 feet once you take the height of my floor into consideration.
Pretty cool, huh?
As the chart below shows, there are–again–four zones to deal with when you’re using a dial gauge canner:
The different zones allow you to better fine-tune the pressure in your dial-gauge canner, so that you only have to use exactly what you need to kill all the canning cooties inside the jar … without unnecessarily hammering the texture of the food by using a single foot-pound of pressure more than you really need. On some foods, it doesn’t make that much difference in the texture if you can them at 12psi with a dial-gauge canner … or at 15 psi on a weight-gauge canner. On other foods–especially the more delicate ones–it DOES make a difference … which is why some people insist on extremely-accurate dial gauges on their canners. However, that multiple zone system does make dial-gauge canners much more tedious to work with … especially since canners have this annoying habit of changing temperature and pressure without you touching either the pot or the burner controls.
As far as the length of time required at these various pressures goes, that’s where pressure-canned tomato products REALLY get difficult to figure out without using an actual NCHFP-approved recipe. The examples they give you are:
- Spaghetti Sauce without Meat, unacidified and contains onions, peppers/celery and mushrooms; cans for 20 or 25 minutes, depending on if you use pints or quarts,
- Spaghetti Sauce with Meat, unacidified and contains meat, onions, peppers/celery and mushrooms; cans for 60 or 70 minutes, depending on if you use pints or quarts,
- Mexican Tomato Sauce, acidified and only contains peppers and onions: cans like Spaghetti Sauce without Meat, 20 0r 25 minutes,
- or Tomatoes with Okra or Zucchini, unacidified, with nothing other than onions added: cans for 30 or 35 minutes, based on pints or quarts.
Looking over that, a couple of things jump out at me:
- as always, the recipes featured on the NCHFP website are the result of scientific experiments performed by different scientists who worked on different recipes: either individually or in groups. They each took different, scientifically-sound routes to reach the same objective: a repeatable recipe that creates a canning cootie-free jar full of a specific desirable food or combination of foods, one with an extended shelf-life at room temperature. These different, scientifically-sound routes include–but are not limited to–acidification, heat/pressure, and duration. This explains why–in some cases–the different recipes seem to be … well … very different
- as expressed in one of the papers published on the NCHFP site–where they were studying salsa, peppers and onions seem to work very well with tomatoes. The paper specifically states: using the correct amount of bottled lemon juice (1/4 cup per pint) full pint volumes of either onions or bell peppers are safely acidified. This lends further strength to the impression you get above that peppers and onions can be safely added to any tomato-based product in any volume, and–as long as you use valid processing times/methods for the tomato product–your peppers and onions are covered, too.
- even though I don’t have a separate published paper to back this up, it also appears–looking at the approved recipes–that celery and mushrooms can be added to tomato products, too … and that the normal processing times for tomatoes will cover them adequately as well, without any additional adjustment.
- zucchini, okra, or other vegetables–when added to tomatoes–DO require additional processing beyond the normal time/temp/pressure needed for the tomatoes themselves. How much time is the problem. In the case of okra and tomatoes, the processing time (30 minutes for pints, 35 minutes for quarts) is longer than the time required by okra: 25 minutes for pints/40 for quarts. The difference between pints and quarts–as you can see–is also not consistent from recipe to recipe. And then–if you look across the various veggies that the NCHFP says you’re allowed to can–you’ll notice that zucchini is missing. In fact, the NCHFP withdrew their recommendations for canning zucchini–and all squashes–in general … but then there are recipes like this one where you can combine it with tomatoes–which are heavily acidic themselves)–and another one where you can make what they call “Pineapple Zucchini“–with almost equally-acidic pineapple, that has lemon juice added on top of that further acidifying the mix in the canning jar. One might suspect with that obvious acid pairing that you could potentially add acid foods to any no-no foods and make them suddenly and miraculously “can-able” … but, again, these are individual recipes … that were approved for canning based on a specific recipe … that survived lots of laboratory testing. That may NOT translate into any sort of rule concerning the no-no foods in general.
- adding meat of any kind to your tomatoes DEFINITELY requires a MUCH HIGHER amount of processing time … and I’ll delve into this more in a minute.
Together, these five observations paint a picture that–despite the joker in the bunch … the zucchini–begins to show somewhat of a pattern here. However, we need to look at all of the food groups before we can see the true, total picture.