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Canning 202: Low-Acid Vegetables

The acidity of a vegetable determines whether is should be processed in a water bath canner or a pressure canner. Low-acid vegetables (in fact, any low-acid food) do not contain sufficient acidity to destroy Clostridium botulinum bacteria, the bacteria responsible for botulism. This illness is a rare, but serious, paralytic condition caused by the toxins the botulinum bacteria produce under anaerobic conditions, or where air is not present, so even if your jars are sealed as tight as Fort Knox, if you haven’t raised the temperature of the contents sufficiently to kill the botulism spores present, you’re still gambling with the health and lives of yourself and your family. (Botulism is found in the soil all around you. The spores are akin to seeds, dormant, just waiting for the right conditions to grow. No matter how sanitary you are, botulism is present on most fresh food surfaces. Because they only grow in the absence of oxygen, they’re harmless on the surface of such foods.)

The spores are destroyed when food is cooked to temperatures of 250ºF for three minutes. However, home canners only raise the temperatures to around 240ºF. It’s possible to kill the spores at this lower temperature, but the food must be exposed to that lower temperature for a longer period of time to destroy the spores. It is impossible for water bath canners to reach these temperatures at all.

So Where Do We Start?

We start with the basics that you learned in the first article on pressure canning techniques—Canning 201. First, a word of caution, however. If you have a flat top ceramic stove, please contact the manufacturer to see if your stove surface can handle the canning process. Because canners are so big, they naturally extend beyond the burner surface itself. The glass outside the burner area is usually not tempered enough to withstand the heat that is generated during the canning process. You risk damage to your stove surface. Instead, use a sturdy electric portable single burner countertop model, or use a propane burner such as you may have with a catfish cooker or other exterior appliance. A Crisis Cooker is also an excellent choice as it adapts to different fuels—wood, charcoal, or propane. For canning purposes however, you’ll want to stick with the propane option.

Compared to water bath canning, you’ll need sufficiently more headroom in your jars—approximately 1 to 1¼ inches. This allows for expansion as the food processes, and allows for the formation of a vacuum as the jar cools. How much your food will expand depends on how much air is present. Raw-packing introduces more air into the jar, and your food may discolor somewhat after two or three months (this is cosmetic only). Hot packing helps remove the air from food and improves the shelf-life of your canned goods. However, hot-packing is a little more time consuming. Because my time is limited, I usually choose to raw-pack when I can, and I’ve had no problem with the shelf-life of my goods. The color of my veggies may not be magazine perfect, but they eat just as well!

Venting your pressure canner before sealing it with your weighted gauge or the counter-weight (if using a dial gauge) is vitally important. Raw-packed foods are especially notorious for introducing the highest amount of trapped air in canners. This trapped air lowers the temperature obtained when the canner is pressurized, resulting in under-processed foods that can spoil. All canners MUST be vented (and by vented we mean a heavy, almost whistling, steady flow of steam, not a wispy little vapor every once in a while) before being pressurized.

The Green Bean

Perhaps the easiest of the low-acid foods to can, green beans can be canned either raw- or hot-packed. Hot-packed will introduce less air into the canning process, so the following is the recipe for that process.

1)  Assemble your jars, lids, screw bands, and utensils. Wash your jars in hot soapy water and rinse well. Keep them in hot water so that there’s not a temperature shock when placing them in the canner. You don’t have to sterilize jars used in a pressure canner. Place your lids and screw bands in a pot of simmering hot water (about 180ºF), but don’t allow them to boil. Boiling will break down the rubber seal.

2)  Get your canner ready. Put two to three inches of water and maintain a simmering water temperature (again, about 180ºF) until all the jars are filled and placed in the canner.

3)  Choose beans that are fresh, young, free of blemishes, and crisp. Wash them thoroughly in water, and then trim them to remove the strings. Cut or break them into similar-sized pieces.

4)  Take your prepared green beans, cover them with water, and boil them for 5 minutes. Remove them from the heat.

5)  With a slotted ladle, spoon your hot beans into the jars, adding 1 tsp. of salt per quart of ½ tsp per pint if desired. Once filled, pour your hot cooking water over the beans, leaving 1 inch of headspace.

6)  Using your jar spatula, run it around the inside edges of the jar several times, manipulating the beans to remove trapped air bubbles.

7)  Check the rim for any nicks or cracks that would cause a seal failure, wipe clean with a warm, wet rag, and place the lid on the jar. Tighten the screw band finger tight. Place the jar in your canner. Repeat with each jar.

8)  Cover the pressure canner, adjust the heat, and vent for 10 minutes. Place the weighted gauge or pressure regulator over the vent pipe and bring the pressure up to 10 lbs. Adjust poundage for those altitudes higher than 1,000 feet above sea level if using a weighted gauge canner (2,000 feet if using a dial gauge) according to the chart below. Processing times are still the same.

ALTITUDE CHART FOR CANNING VEGETABLES

ALTITUDE DIAL GAUGE CANNER
Pints and Quarts

WEIGHTED GAUGE CANNER
Pints and Quarts

1,001 – 2,000 ft. 11 lbs. 15 lbs.
2,001 – 4,000 ft. 12 lbs. 15 lbs.
4,001 – 6,000 ft. 13 lbs. 15 lbs.
6,001 – 8,000 ft. 14 lbs. 15 lbs.

9)       Process pints for 20 minutes and quarts for 25 minutes. If using mature beans that were almost at the “shell-out” stage, add an additional 15 minutes to pints and 20 minutes for quarts.

10)   Turn off the heat to the canner and allow it to cool and depressurize naturally. Do not force the canner to depressurize. After the canner has reached zero pressure, open the vent and move the lid. Allow the jars to sit in the canner another 5 or 10 minutes to adjust to the lower temperatures.

11)   Using your jar tongs, remove the jars from the canner, keeping them in an upright position so as not to disturb the lid. Place on several layers of towels so as to avoid temperature shock from a cool countertop. All the jars to cool for 12 to 24 hours. Check the seal by gently tugging on the lip of the lid and pressing down in the center of the lid. If the center of the lid is countersunk and you can’t move the lid with gentle tugs on the edge, your jar is sealed. Remove the bands, wipe the jars down, label, and store in a cool, dry place. Any jars that did not seal can either be reprocessed for the full amount of time or put into the refrigerator and eaten immediately.

One thing to remember, when canning multiple vegetables together, is to use the processing time for the longest cooking food. So if you’re processing five quart jars of beans (25 minutes) and 2 quart jars of black-eyed peas (40 minutes) you would process the canner load for 40 minutes. Use this formula when mixing vegetables in the same jar as well. For example, if you like to have potatoes in your green beans, then you would process a quart jar of the two mixed for 40 minutes, the length of time it takes to process potatoes.

Once you become familiar with your canner and the canning process, and begin to feel more comfortable with what you’re doing, you’ll want to begin to experiment with many different combinations and foods. Just remember, avoid recipes with dairy, flour, or rice in them. This includes noodles. These ingredients are too dense for home canners to thoroughly heat through, and again, without sustained temperatures of 240ºF, you risk illness and possibly death from botulism.

Coming up next week—Canning 203: Meats

© 2008-2014 Off The Grid News

35 comments

  1. If I do not have a presure cooker can I still can veggies with a water bath. I already do tomatoe and fruits.

    • MississippiGirl

      Silvermoon, no you can’t. This previous article clearly explains why low-acid vegetables have to be canned in a pressure canner. http://www.offthegridnews.com/2011/04/25/canning-201-the-pressure-canner/ A water bath canner cannot reach the temperatures needed to kill botulism spores, and it’s those tasteless, odorless spores that can kill you with improperly processed foods. You can get one that will can 7 quarts or 19 pints for around $90 at Walmart.com. Even if you have to save your pennies or sell something to get the money for one, do it. It’s one of the best investments you can make.

      • I like your website, but don’t tell me you can’t do green beans in a water bath! When we have done them that way all our lives.
        What will you do if you don’t have a pressure canner and need to can beans or meat? Let it spoil when there is a way to can it other wise.
        How did they can before pressure canners?
        Would you like to come to our home and see how it is done?
        Not to be smart but I am tired of hearing this from the Extention Offices, books and now your website.

        • If you do not have a pressure canner & don’t want to go to the expense, I highly recommend blanching & freezing your green beans. They retain all the green color, and remain alot crisper. My husband & I purchased a vacuum sealer a couple years ago, and I have found that I prefer the frozen beans over the canned. If you’re concerned about them lumping into a frozen mass, try flash freezing in a single layer on cookie sheet lined with parchment paper for an hour after blanching & draining, then vacuum seal. Good Luck.

        • If you do not can properly then you are playing Russian roulette with the lives of your family. If you get prompt treatment then their lives can be saved by being put on a ventilator for months. This will cost far more than you can possibly save by canning in a lifetime! Canning is only safe if it is done correctly. BTW I got Clostridium perfengens food poisoning that I believe was from home canned green beans. I was very sick with severe diarrhea for a week. I was very lucky. If you cannot pressure can then you can freeze of dehydrate food or just throw it out. Do not be penny wise and pound foolish!

    • Gotta use a pressure cooker. In the early 1900s non-acids were canned in water baths but it was cooked for hours and still not safe.. Pressure cookers are available pretty cheap now-a-days. Check online auction sites and don’t forget to replace the pressure gauge and not rely on the one you get, or even better yet get a cooker with a rocker relelief and then the gauge isn’t that important and another advantage of the rocker relief is not having to eyeball the pressure gauge all the time to regulate the heat source and can get other things done.

      Good luck.

  2. I was wondering when you pressure can your vegetables, how much of the vitamins, minerals etc. are destroyed by bringing up the temperature so high. I want to be prepared but I don’t want to destroy the nutritional value of the vegetable or fruit either.

    • There is some degredation of vitamin content in heating (or even storage for a few hours in the refrigerator). Minerals cannot be destroyed by cooking at normal temperatures (unless you ash your food ). The alternative to storage is to use garden fresh and to rush it from harvest to the table! Delicious and nutritious, but often impractical.

  3. Let me open my big mouth and say, Yes, you can do your green beans without a pressure canner.
    Yes, with a pressure canner you will probably have a less chance of something going wrong.
    BUT! we have canned Green Beans for years, My parents did and my grandparents did in a water bath canner. And Meat too!
    Sterilize your jars and lids, open kettle the green beans first, put them in the jars with a teaspoon of salt and process for two hours, bring to a boil and cook for 2 hrs.
    I don’t like to contradict anyone but it is done now and has been done for years without anyone dying.
    I am 64 years old and my wife and I have done this all our lives, so don’t let anyone tell you, you can’t!
    We never had a pressure canner until later years to can fish, so the bones cook up, until then you picked the bones out.

    • MississippiGirl

      Well Concerned, I’m proud you’re still with the living after all these years of simply water bath canning vegetables and meats, especially fish. You’ve been incredibly lucky. My friend thought the same way you do… until she lost her entire crop of green beans that she spent hours upon hours putting up by water bath canning. You may live under a lucky star, but for the rest of us mortals, we don’t hit lucky sevens every time we roll the dice. I will not put the lives of my family in jeopardy, and if pressure canning insures they don’t get sick from the food I store, then so be it. I’d rather be safe than sorry.

      • I don’t think it has anything to do with the stars, just good common sense. I’m not saying that pressure canners don’t have an advantage.
        I just tell you that it can be done in a water bath, 3 generations of our family is proof enough for me and who knows how many before that.
        When your pressure canner breaks and you can’t get parts, Remember the Kook who told you it can be another way.

    • Chickenscratching

      I don’t think that this article was about whether you “can or can’t” as much as it was about whether you “should or shouldn’t”. I know I “can” drive to town without wearing a seatbelt and I “can” cross the street without looking both ways, but I “should” use better judgement and choose the safest option. . . after all, my life may depend on it!

  4. M.L. Abramowitz

    Thank you…good infomation for us newbees.

  5. Boiling water is 212 degrees F at sea level. It does not matter if the water is simmering (heat very low) or rapidly boiling (heat source maximum). At 15 PSI steam pressure in the presser cooker the temperature is 256 degrees at sea level.
    I have canned for over 40 years the most in one day was 77 Quarts of new potatoes and over the most in one year 500 quarts of green beans. I have eaten potatoes that were canned over 20 years and they were still “eatable”.

  6. to newbee’s please be safe then sorry. Yes our grandparents did things different out of neccesity but then only the hardy lived. Many people today do not have the resistance to bugs that our grandparents did. If you don’t have a pressure cooker then you can pickle them where the vinigar gives you the acid to be safe.

  7. I see packages of citric acid in the canning departments. Does anyone know how much citric acid one would have to add to say a pint of green beans, to bring the acidity up to a level that would allow for water bath? I just bought a pressure canner, but my beans are not putting on yet. Or am I just asking for trouble?

    • I agree with socalgal. It’s so better to be safe than sorry. Maybe some of our ancestors di hot water bath veggies and meat but veggies and meat just aren’t what they used to be. Variety’s are less acid, animals aren’t fed with the nutrient rich ground there once was and neither is it so when planting a garden. Things just aren’t the same! Just because something’s been done doesn’t mean it’s the best and safest way. Pressure cook your meats and veggies and have peace of mind. I’ve been canning for 50 years and it’s the safest way.

    • No need to add acid. Salt them, like cabbage for kraut, let’em ferment and can in water bath.

  8. The correct word for “eatable” ….is edible!!

  9. If any of you “newbies” are concerned with the cost of a pressure canner just imagine what the expense will be for a stay at your local hospital recovering,if you are lucky, from a dose of botulism.I recently purchased a 22 pint or seven quart Mirro pressure canner for less than $95 from Sears and it is worth every penny.I had in the past water bath canned my vegetables but the risk involved was too great not to start pressue canning.I always give away some of my excess canned produce to my friends and neighbors and the thought of poisioning them was too great a risk to contemplate.Be careful,do it according to instructions,and above all enjoy the bounty of the good earth.

  10. This may be a stupid question, but if temperature is the determining factor in the types of canning, couldn’t you get water to a higher temperature if you placed the canner in the oven? Maybe the jars would break? I don’t know, but I thought I’d ask. Maybe someone out there has an answer.

    • I haven’t canned in years but I remember that you can only get water to 212 deg F unless you put it under pressure. That is the reason that your car’s cooling system must have a pressure cap, I’m a mechanic. That is why when camping in the mountains that you have to put a cover on a pot to help bring up the temp and why you must increase the canning time if you live in the higher elevations. We use different items to make the water react as if it were at or below sea level. Water is wonderful stuff but dumber than a rock so we can fool it easily.

      God Bless
      R D

    • Chickenscratching

      “Water” can only be heated to at certain temperature and then it is no longer water, but steam. The pressure cooker is a closed system that allows the water fo become steam and therefore reach higher temps. Water in the oven would simply heat up, turn to steam and escape.

  11. boband shannan

    I’m looking for information on canning at high altitude. Specifically 8500-9550 ft in elevation. All charts I can find stop at 8000 ft and with food, I’m concerned that might not get the job done and don’t want to risk illness.

  12. If you have low acid foods and want to can them in a water bath, you can do so by increasing the acidity of the food by adding vinegar to each jar. Doesn’t really change the taste, adds nutrients if you are using organic apple cider vinegar, and tenderizes meats.

  13. Good article! Question: How long should you pressure corn to can it? Consider: Whole kernel and cream-style corn. Thanks.

    • Off The Grid Editor

      Corn is pressured canned at 10 pounds of pressure (adjust for altitude if it applies to you) at the following rates:
      Creamed – 95 minutes in pints – not recommended in quarts (density issues and inability of home canners to adequately penetrate the contents to properly heat the food to needed temps)
      Whole kernel – 55 minutes in pints – 85 minutes in quarts

  14. For those new to canning, I would like to suggest obtaining an invaluable tool called the “Ball Blue Book for Canning.” This book has been around for over 65 years, as my mother remembers her grandmother having a copy of it when she watched her grandmother canning her garden vegies. It has specific instructions, charts and graphs in it for canning all kinds of fruits and vegies, including how much salt, citric acid, how much pressure, how long to cook, etcetera. My 74-years young mother told me the other day that she finally went and bought the new edition because her heirloom copy fell apart from age! ;-D

  15. Suzanne Chastain

    Having been canning and helping my mother (a home economics major in the 1930′s) to can for 40-50 years, I am enjoying reading these comments. The folks that insist on using water bath canning for everything will not change their minds now. If they get sick, then they will know why. If they don’t, then they were “lucky.” I don’t know how my grandmother canned, but my mom ALWAYS “went by the book,” and explained why–as you have here. Those that choose to listen and heed, will be successful and safe. Those that choose to take another route or rebel, because “they’ve always done it that way,” may face sad consequences. I would rather be safe than sorry, as several have stated. There are always a few that insist on doing things “their way.” Sadly, ‘their way’ may get them killed.

  16. I have had people tell me they put their oven on and then shut it off when it reaches a certain temperature, so that they can put their canning jars in there to seal the lids, and they said they can hear the lids pop. Don’t know how that is, but I only use a canner. Ive been canning tomatoes, green beans, potatoes, tomato sauce, etc, and i either use citric acid for the acid stuff, or i use Morton’s canning salt for the rest. And sometimes i even use vinegar, just depends on what your canning. I have canned blackberry jelly, blackberry jam, etc. In the past when they didnt have canners, or water baths, they used something entirely different, probably a wood stove and put their jars in old pots to sanitize and after the jars were sanitized and food was cooked they jarred their foods, and put the jars in the same pot with lid on the wood stove. My grandparents did it this way, and they lived a great life. As long as you are leaving good headroom space, nothing should spoil, or get bad as long as its going to a rolling boil for 2 mins, If thats what you have to work with, keep checking your canned vegetables on your shelfs time to time, so it avoids, botulism. Great opinions ….goodluck everyone.

  17. I bought a pressure canner 2 years ago, and really love it, but it is the new kind, with the pressure gauge instead of the old “jiggler” type, and through the process of pressure canning, I am a total stressed mess!! After it gets to the right pressure, I have to stand right there to keep turning down the stove (electric) to make sure that it stays at that pressure, and then keep checking every few minutes to make sure it is at the correct pressure. Anybody have any tips to make this more enjoyable, and not stress oriented? Makes it kind of tough when I have to do this for 90 minutes or so………(For the last 30 years or so I canned with the old Jiggler type pressure cooker, but finally it died on me, and the only new ones I could find were the gauge kind.)

  18. I have just started to can greenbeans, in a open canner now i’m afraid of my greenbeans. Can i reprocess them now after they have set for a few days? I have purchased a pressure canner?

  19. I’d like to continue this thread from a different perspective – the profit motive – either pot manufacturers wanting to sell you a more expensive pressure system or bloggers with hidden links to food processors who would like to discourage people from being independent of their (too often adulterated) food. Both have reason to scare you.

    Many folks have obviously water bathed their jars for generations without a problem. It is also obvious that botulism is serious and real. The problem probably occurs when newbies do wrong things, especially being sloppy with their prep/ washing/ cutting boards/ utensils, time, dust blowing in from garden, etc. Old timers didn’t make mistakes (or they got terminated as a Darwinian benefit to humanity!) Modernity broke the family and self reliance so the experience factor got trashed.

    Spending a hundred bucks on a safer alternative is no big deal, even poor people often waste more than that in dumb ways like smoking, bingo and lottery tickets. Locally, the cost is C$120 and$140 at Canadian Tire. But should we buy the whole danger based argument?

    Well, we’re newbies at this, we’re not broke and life is short so the answer is an easy ‘yes’. But if you’re in a different situation and don’t mind being paranoid about procedure and/ or undertaking the extra effort of controlling acidity or salt levels, then perhaps you can ignore the doomsters. To put this another way, if you drive a VW Jetta diesel, you could probably use the water bath, but if you drive a domestic station wagon and do your canning after the kids fall asleep, you better get a pressure canner!! Regardless, err on the side of caution. Good luck to all.

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