Water Bath Canning 101

Sharon July 17th, 2008

Ok, today’s subject will be canning and lactofermentation.  I’ll start with the canning.  Today’s subject is Water Bath Canning, which is different than Pressure Canning – we’ll talk about the latter next week.  I’m going to start from the very beginning here – I know lots of people who read this blog already have a lot of experience on this front, but just in case you don’t, it is worth going over the basics.  The first thing I’m going to say is that I don’t want you to be scared, and I don’t want you not to try this, but I do want you to swear up and down before you do any canning that you will pay attention, read instructions carefully and follow the rules.  Because, even though your Mom always did it this, you really can die from not being careful with canning.  It probably won’t happen – but why mess with it?  Properly done, canning is easy and safe – just do it properly.

Water Bath Canning is the appropriate method for canning *only* high acid foods.  Such foods include pickles, jams, jellies, fruit juices, rhubarb (which is technically a vegetable but so acidic it can be water bath canned) and all-tomato products.  Everything else must be pressure canned.  The reason for this is that the bacteria, clostridium botulinum, that causes botulism, is endemic the soil – it is all over your vegetables and fruits in most cases.  That’s not a problem in an aerobic (there’s plenty of air) environment – your body can handle it just fine (although babies under 1 year sometimes have trouble with it).  But in a warm, anaerobic environment like a canning jar, it goes crazy.  And botulism will kill you and your family – it is not something to mess with.

Now any food with a ph lower than 4.4 (acidic) provides an environment inhospitable to botulism – which is why high acid foods can be safely pressure canned.  But, the thing is, most of us don’t have the chemist’s equipment to confirm acidity – for example, tomatoes can have an acidity level as low as 4.0, or as high as 4.7, if they are overripe or a low acid hybrid. And there are a couple of cases of botulism found in tomato products.  This is why following the instructions of a *RECENT* canning book is essential – any cookbook written before 1994 is not safe to use – that is, you can use the recipe, but you must follow current guidelines for canning – generally speaking, if you aren’t using just fruit and sugar, or pickles, but mixing ingredients, say, in tomato sauce or salsa, you must follow the instructions for the ingredient in the food that requires the longest and most intense processing – that is, if you are making salsa with tomatoes and hot peppers, unless you know the recipe is safe (that is, you have gotten it from a USDA approved, recent book or website that specifically says that it is a combination food that is safe to water bath can, *AND* you have followed instructions exactly, not adding any more ingredients or changing proportions at all).  For tomato products with nothing else in them, add 2 tsp of lemon juice per pint, or 4 per quart, or the same amount of vinegar, to ensure their acidity stays below minimum levels.  This might also be wise if you are canning very overripe fruit. 

Ok, for canning you need a few things.  You need a large pot with a lid – canning kettles with racks are great, but you can use any big pot with a lid, and something to keep the jars off the bottom of the pot so they won’t break – a steamer, a baker’s rack – anything that will lift the jars off the bottom and allow water to circulate.  Ideally, you will also have a canning kit – it comes with a jar lifter (big tongs designed to lift full canning jars), a magnet (for pulling the lids out of boiling water), and a funnel the right size for pouring hot things into canning jars.  You don’t actually need these things – they are merely convenient – but they are really convenient, and nice and cheap, so I recommend them.  You can take the jars out with regular tongs – I have done this.  I’ve also had one splash back and send boiling water at me – your choice.  You can fill the jars without the funnel, but why struggle?  The stuff is also available used at your friendly neighborhood yard sale.

I have never bought a new canning jar – I get them constantly for a buck a box or sometimes $3 for 5 boxes – they are one of those things most people seem to have in their garage.  Put out requests on freecycle or Craigslist, and see what you can find before you buy them.

The only ones that are really considered safe to use are the newer kind, that have two piece, screw on lids.  The old ones with the jar rubbers can technically be used for high acid foods, but they aren’t recommended, can only be used with new rubbers, and I’m not going to explain how to do it here, because there’s a lot of controversy about whether it is safe.  If you have the old zinc lid or wire and rubber canning jars, use them to display stored food, or store dehydrated stuff – don’t can with them.

You also don’t need to buy new rings – as long as the rings aren’t rusted through, and as long as they fit on the jar (often canning jars come with the rings), you can reuse them.  These I occasionally do buy new, as not all jars come with them. 

You need a new lid every time – and jars come in two sizes – regular and wide mouthed.  So you not only need a new lid, but an appropriately sized one.  I buy my canning lids buy the case, because I do a lot of canning – they store for quite some years as long as they are kept cool and dry, and are much cheaper if you can afford to buy them in bulk. 

Now in a real crisis, it is technically possible, although NOT RECOMMENDED to reuse lids that have been carefully pried up and checked to ensure there are no dents or damage to the rubber inside – BUT ONLY ON VERY HIGH ACID FOODS.  I am telling you this because in a real crisis, it might be useful knowledge.  I do not advise it – you do it at your own risk.  At a minimum I would never, ever, ever use it on any low-acid or even borderline food  – pickles and acid fruit jams only.  The best use for used canning lids is for jars of food that you are dehydrating and storing, or for mason jars you fill with beans and grains that aren’t canned.

So what do you do?  Let’s say you want to make raspberry jam.  You would take fresh (you really don’t want to leave your stuff sitting around too long before you can it – off flavors can permeate a whole batch of something) raspberries, add sugar to taste or to meet the requirements of the brand of pectin you are using (we use low sugar pectins only because we find regular ones make a jam that is simply too sweet for us), and follow the instructions for the pectin. 

In the meantime, wash your canning jars and lids carefully, and check the jars for tiny nicks on the top, because that can ruin your seal.  Then submerge the jars in a pot of boiling water that comes up at least 2 inches above the top of the jars.  Bring the water to a boil, and boil the jars.  Meanwhile, boil the lids and rings as well.  When your jam is hot and ready to be ladled in, use the jar lifter to take out the jars, and put them upside down on  a clean dishtowel to drain.  Then flip them, and use a ladle or spoon and the funnel to fill the jars to the recommended headspace.

Headspace is the amount of space between the food and the lid that you need to create a good seal.  Often it is 1 inch, but check the recipe every time, because it may be more.  When the jar is filled to the appropriate level, wipe the rim of the jar with a clean dishcloth to remove any food that might prevent a good seal, put the lid on, put the ring on (not super tightly – enough to hold the lid in place firmly), and use the jar lifter to pu the food in the canning kettle.  Process for the appropriate amount of time listed for the ingredient – jams are usually 15 minutes.  Processing time begins when the water returns to a rolling boil – start timing then. 

When you are done, use the lifter to take the jars out of the boiling water bath, and put them carefully (don’t bang them around) on a clean, dry dishtowel.  You will hear a seal being formed within a few minutes – the sound is “thwuck”.  Some will seal right out of the kettle, others a few minutes later – this is normal.  Allow the food to cool without being disturbed.  When the jars are cool enough to touch, press down on the lid.  If it is suctioned down and has no give, it is sealed.  If you can push down on it and it pops up again, it isn’t.  If it isn’t sealed, you can either reprocess with a new lid for the same amount of time, or you can stick it in the fridge and use that one first.

 You may have been taught to can by someone who did oven canning (jars are baked), inverted the jars to create a seal, or did open kettle canning (poured hot food into jars and put on lids and let them seal themselves) these are not safe – DON’T DO IT!!!!  Neither are weird things like putting an asprin (ugh!) in the jar.  There have been cases of botulism with some of these methods, others could potentially cause botulism.

None of this means, however, that you can’t use Mom’s wonderful pickled beet recipe – you just have to use current techniques to can that old recipe. 

That’s really all there is to water bath canning.  It is very easy, and very convenient, as long as you do it wisely. 


19 Responses to “Water Bath Canning 101”

  1. [...] Casaubon’s Book » Blog Archive » Water Bath Canning 101 Ok, today’s subject will be canning and lactofermentation. I’ll start with the canning. Today’s subject is Water Bath Canning, which is different than Pressure Canning – we’ll talk about the latter next week. [...]

  2. Rosa says:

    Yay! Canning!

    I have a pressure-canning question you might have the answer to. Usually I freeze shredded zucchini for zucchini bread (and adding to random food, since it pretty much disintegrates).

    Have you ever cooked with canned zucchini? Does it lose its structure too much to use in quick bread?

  3. Paula Hewitt says:

    thanks – this is very useful. I have a canning bath and some jars, but none of the accessories or instruction manual – i think you have saved us all from an untimely death by badly pickled something. On another note, and I have to tell you because no one I know in real life (except my husband) cares – I have started stockpiling food – several kgs each of lentils, beans etc, approx 10 kgs of brown and white rice, wm pasta, tinned tomatoes, jars of passata etc. i have cleaned out a cupboard in the laundry for stocks of TP, soap, medical supplies. Each time I go shopping now I will add to it until i have a sufficent stockpile and then i will start to cycle through it. Even having a few months of ‘rice and beans’ meals make me feel better – so thankyou for the push. (I have also bought a heap of heritage, open pollinated seed for the veggie garden, so we arent relying on seedlings from produce store anymore). ps I have been reading all your old posts from the beginning – the more I read the more I like you!

  4. Sharon says:

    Good for you, Paula – that’s excellent!

    Rosa, I’ve never tried canning grated zucchini – it is worth a shot, but as you say, it might get mushy. I’d think you could still use it in bread, though.


  5. Meadowlark says:

    OK, lentil soup. I find split pea soup recipes, but is there something weird about canning lentil soup that makes me unable to find any?

    And thanks for this. I am slowly working up my courage to can something – I’ve had my canner for over a month now. This is one more push in the right direction.

  6. Rosa says:

    Paula, Meadowlark- you can get the whole USDA canning guide at http://foodsafety.psu.edu/canningguide.html.
    It’s mostly for pressure canners because so few things are water bath safe.

    I have gone through most of my canning recipes & marked them up with processing times from that guide, writing down the date I updated them, since many of them were not safe by the post-1994 standards.

  7. anita says:

    Also, if you pour the almost-boiling water (left after removing the jars) down a drain it will help keep it clear. Especially if you live in a house with elderly drains (we just keep a spare plunger in the kitchen) and a septic tank . . .

  8. Jill says:

    Hi, just found your blog through a post from Crunchy Chicken. Perfect timing too, as I’m about to make pickles for the first time ever…and I don’t even eat pickles! But ever since Nalley’s and Steinfeld’s decided to use cucumbers from India instead of the Northwest, I’ve told my pickle loving boyfriend we won’t be buying them anymore…happy to see your post on canning- now to get the tools and the cukes! Thanks!

  9. Lisa Z says:

    I’ve read somewhere (prob. online) that canned zucchini is awful and mushy. You could still try a little bit though!

  10. katherine says:

    Here is a useful resource on Canning, etc. along with pick-your-own listings:


  11. Nita says:

    Rosa, I can some summer squash in pints for adding to sauces or soups that will be cooked to avoid the botulism problem. If you use young squash, before the seed cavity develops, and cube it in uniform pieces it will hold up nicely. Look under pressure canner recipes for summer squash for correct processing times.
    I think shredded squash would disintegrate because of the small size.
    I can’t say that it adds anything but color and texture to my lasagna, but I always have an abundance of squash and this is a good way to use it.

  12. eden says:

    “I have never bought a new canning jar – I get them constantly for a buck a box or sometimes $3 for 5 boxes – they are one of those things most people seem to have in their garage. Put out requests on freecycle or Craigslist, and see what you can find before you buy them.”

    Everyone always seems to say this – but if you don’t live in a rural area, or at the very least an area with a lot of elderly people who used to live in a rural area it’s not true. In the past three years I’ve only seen one person offer canning jars on freecycle or craigslist – and they were taken within hours. I’ve seen hundreds of requests. I’ve also never seen them at yard sales.

    I recommend looking through your local freecycle archives – if you don’t see many/any offerings of canning jars, I recommend buying new ones – otherwise you’ll be looking for a long time.

  13. Sarah says:

    Eden — yeah, same here. I managed to score a box of rather elderly quarts at the thrift store last winter, but that’s the only time I’ve seen them. At least buying new ones for me involves supporting a nice independent hardware store :-)

  14. Nancy says:

    I have canned in the past but mostly things like tomatoes, salsa & figs.
    I never tried to can conveniance foods like soups or pasta sauces I was always afraid to try. But with the high prices I think it’s time to give it a try. I have a pressure canner and yesterday after a serch for many recipies and canning information on the web, I thought I would try to make split pea soup. It came out great but now I’m not so sure of myself the soup has gotten so thick in the jar i’m afraid that it didn’t heat through like it supose to. I made 10 pint size jars and process them for 75 minutes on 11 psi. Should I add more liquid and process them again are was it supose to thicken up like tomatoe paste. I need help.

  15. [...] stays good for two years or more (it usually gets eaten first!). But feel free to consult with canning enthusiasts from [...]

  16. Lee Johnson says:

    We haven’t tried it yet, but I’ve read that drying zucchini works quite well. I wonder if it might have a better consistency for use in zucchini bread as well. I hope to build a solar food dehydrator this summer, but not sure if we’ll get to it with all the other projects in progress.

  17. Dehydrated zucchini is THE BEST!! (and pumpkin and other squashes) Simply throw it into your soups, stews, pasta sauces and no one knows the difference!! Best of all… it shrinks down quite small, but reconstitutes almost as a thickener. (So now you have something to do with ALL those zucch’s, without having your friends hide when you say, “do you need any….!!”)

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