Water Bath Canning Tutorial, by Feral
Last Updated :: 9/30/2007 5:53:22 PM
Water Bath Canning, by Feral

Canning in a water bath canner is a straightforward proposition. If you can follow a recipe, you can use simple, easily available equipment to preserve a variety of foodstuffs. This post is my initial attempt to show the basic steps in water bath canning; the focus here is on the steps involved and not the recipe, though in this case the food being prepared is tomato soup.

Before getting into the technique of water bath canning, let's look at some important things to know about home canning. (If you just want to see the pretty pictures----scroll down.

Why do foods spoil and how does water bath canning prevent spoilage?

Foods spoil for two principal reasons: presence of microorganisms and enzymes naturally present in the food. Proper canning technique kills or inhibits the microorganisms and de-activates the enzymes that lead to spoilage. To accomplish this, home canning relies on airtight containers, heat and acidity.

Using proper containers isn't difficult. You simply have to lay in a supply of modern jars that accept two-piece closures. (More on that later.) Jars that have bale closures or one-piece lids are not acceptable for modern home canning. Some of these jars are very pretty--you can use them to store dry goods, but don't put them in your canner. Also, don't reuse store-bought jars that held mayonnaise, pickles or whatever: these jars were designed for one-time use and are not safe home canning enclosures. In short, if it doesn't take a two-piece closure, don't use it.

Completely immersing the jars in boiling water long enough to heat the contents of the jars thoroughly provides the principal means for preserving the jars' contents. Modern recipes, such as those found in the Ball Blue Book, have been specifically tested to match appropriate processing times with any given recipe.

It's helpful, at least for me, to have a basic understanding of the microbiology of spoilage microorganisms. At 40 to 139 degrees F molds, yeasts and bacteria thrive. Raising the temperature into the 140-179 degrees F range inhibits the growth of these bugs, but doesn't destroy them. Raising the temperature into the 180 - 212 deg F range destroys most of them. But note that the toxin produced by Staph. aureus and the spores of Clostridium botulinum are not destroyed at this temperature, only inhibited when processed at 212 deg F. To destroy these poisons, food must be heated and held at 240 deg F.......and this is temperature achievable only in a pressure canner.

So, why then are foods processed in a water bath safe and durable? The reason is that properly prepared water bath recipes are acidic. It's the acidic environment that prevents these potentially deadly poisons from multiplying. And that's why only "high acid" foodstuffs are safe to can in a water bath canner. Foods with a pH (a measure of acidity; lower number means more acidic) less than 4 are safe in a water bath canner. Examples include pickles, apples, peaches and pears. Foods that sit in the middle zone (pH 4-5), such as tomatoes, are also safe but require acidification before processing. This is accomplished with the addition of bottled lemon juice or citric acid. Low acid foods (pH >4.6), such as all meats, carrots, green beans and corn, absolutely cannot be processed in a water bath.

In summary, modern canning jars, sufficient periods of heating and acidity all combine together to make water bath canning a safe enterprise.

The Process

(1) Assemble your equipment: jars, canner with rack, canning utensils.
(2) Prepare your recipe.
(3) Clean the jars and closures.
(4) Pre-heat the jars.
(5) Put your lids in a sauce pan and heat to 180 degrees. Do NOT boil the lids, but DO keep them hot until used.
(6) Fill the jars one at a time.
(7) Place each filled jar in your canner as you finish it.
(8) When the canner is full or you've filled as many jars as you need to, lower the jars into the boiling water.
(9) Process the jars for the time specified in the recipe.
(10) Turn off the heat and remove jars using the jar lifter.
(11) Set your processed jars aside for 24 hours.
(12) Gently clean the jars and check the seals.
(13) Label the jars and store them.
(14) Pat yourself on the back.

The Process in Detail

(1) Assemble your equipment: jars, canner with rack, canning utensils.



(2) Prepare your recipe.


(3) Clean the jars and closures.
We hand wash the jars but washing them in a dishwasher is fine. Discard any chipped or otherwise damaged jars. If there is food residue in a jar that you can't remove (unusual), discard the jar.


You can choose between "regular mouth" and wide mouth jars. Here are the two varieties shown with a "wide mouth" lid. In theory, you'll have fewer seal failures with the "regular mouth" jars, but in practice I haven't noticed any difference. We use mostly wide mouths as they're easier to clean and it's easier to get food in and out of them.


Modern two-piece closures are really marvels of engineering....more on that later.



(4) Pre-heat the jars.
The time honored way to do this is to place the jars in a canner full of water and bring them to a simmer. (You don't need to BOIL them.) We cheat by putting them in a 200 degree oven until they're hot.


(5) Put your lids in a sauce pan and heat to 180 degrees. Do NOT boil the lids, but DO keep them hot until used.


(6) Fill the jars one at a time.
Using a canning funnel is optional, but it really does help keep your jars (and your workspace) cleaner.


Pay attention to the headspace (the distance between the top of the contents and the top of the jar) that the recipe calls for. Don't over-fill or under-fill. Using a clean damp cloth or paper towel, wipe the jar rim clean. This step is important and shouldn't be overlooked; food particles stuck on the rim of the jar cause seal failures.


Use a non-metallic utensil such as a Ball Bubble Freer or a thin spatula to wipe around the inside of the jar. This frees up any bubbles that may be contained in the food and ensures consistent processing.


Pick up a lid with your lid lifter....


....and place on the jar with the rubbery sealing compound centered on the jar's rim.


Tighten the ring carefully. Ring-tightening is more art than science; the Ball book recommends "fingertip tight," which means screwing the lid down gently until it stops, and then tightening it just a little more. Try not to over-tighten (it's like the difference between a firm handshake and a bone-crushing handshake). You'll get the hang of it quickly.


You can use the jar holder to hold the jar if it's too hot. (Note that the jar holder is not used to tighten the lids.) Remeber that the lids need to be able to vent during the processing.....you're not tring to tigthen them so they're "air tight".....the processing will take care of that. Most people can easil tighten lids enough using just their fingertips.


(7) Place each filled jar in your canner as you finish it.


(8) When the canner is full or you've filled as many jars as you need to, lower the jars into the boiling water.
Remember that the processing time starts when you've achieved a rolling boil and that the boil must continue, uninterrupted, for the entire processing time.


(9) Process the jars for the time specified in the recipe.
Make sure your jars are covered with 1"-2" of water during the entire processing time.


(10) Turn off the heat and remove jars using the jar lifter.


(11) Set your processed jars aside for 24 hours.
Don't disturb them as they cool.....this is the time when the seals are setting up. It's gratifying to get a hearty "THWOCK" as the lids sock into place......but don't worry if not all the jars do this. Good seals still occur, even without the "THWOCK."


(12) Gently clean the jars and check the seals.
--need pic

(13) Label the jars and store them in a cool, dark place.
Definitely label them with the date they were processes. You may think you'll remember when you processed a given recipe, but you won't.


(14) Pat yourself on the back.
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Originally Posted By Feral:

Originally Posted By bobwrench:
I dont understand why some have to use a pressure cooker to can.


This may help you:


Canning classifies foods into two groups: low-acid (poultry, meat, seafood, and all vegetables except tomatoes) and high-acid (lemons, pickles, gooseberries, apricots, plums, apples, blackberries, sour cherries, peaches, sauerkraut, pears, and tomatoes, according to the Ball Blue Book). Even "low-acid" tomatoes can be water bath canned if acid is added (lemon juice, citric acid, or 5-percent vinegar).

Low-acid foods with a pH of 4.7 or more can be canned, but require more heat and a different technique, pressure canning. (They're also great hosts for clostridium botulinum, the bug that causes botulism.)
High-acid foods have a pH of 4.6 or less, either naturally or with the addition of lemon juice, citric acid, or 5-percent vinegar....



Originally Posted By bobwrench:
Also when do you seal the jars? I looked like they were seal before they went into the hot water. Won't they over pressure and explode?


The jars don't explode because they're designed to vent gases during processing. This is why you see bubbles coming out from under the jar lids during canning. It's also why you don't want to over-tighten the rings when you apply them. This venting is what allows a vacuum to form during processing, thus keeping out food oxidizing oxygen.

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Originally Posted By DancingBear:

Originally Posted By Feral:

Originally Posted By brassburn:

(12) Gently clean the jars and check the seals.


How do you check the seals?


I have to add a couple of pictures....that's one of them.

Take the rings off your jars. Hold the jar in both hands and use your thumbs to press up, from the bottom, on the lid. A good seal will take a considerable amount of pressure to pop the lid off (obviously you don't want to pop the lid off.) After you checked a few jars, you'll get the hang off knowing which jars are sealed and which aren't by using a little thumb pressure.


Very good job on this post Feral.
Also, a good seal means the lid will be sucked down onto the rim of the jar, and you should not feel any give to the lid while pushing down on the center of it.

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Originally Posted By Kitties-with-Sigs:

Originally Posted By Feral:

Originally Posted By brassburn:

(12) Gently clean the jars and check the seals.


How do you check the seals?


I have to add a couple of pictures....that's one of them.

Take the rings off your jars. Hold the jar in both hands and use your thumbs to press up, from the bottom, on the lid. A good seal will take a considerable amount of pressure to pop the lid off (obviously you don't want to pop the lid off.) After you checked a few jars, you'll get the hang off knowing which jars are sealed and which aren't by using a little thumb pressure.


Don't your lids "pop"--you know--suck down so they have a little dent in them when they're sealed? That was always the fun part of canning for me. I'd actually sit mesmerized and watch the jars after they were set aside, waiting for the "pop" they made when they sealed. We never removed the rings until after each jar sealed. If one did not seal, it got opened and eaten that day, or placed in the fridge for the next day's meal. I can open a sealed jar fairly easily with just my fingernails, and I try to be careful with the seals, but we always removed/re-used the rims.

quote by Feral:


Tighten the ring carefully. Ring-tightening is more art than science; the Ball book recommends "fingertip tight," which means screwing the lid down gently until it stops, and then tightening it just a little more. Try not to over-tighten (it's like the difference between a firm handshake and a bone-crushing handshake). You'll get the hang of it quickly.


This is a great way to put it. And the thing is, for men it'll be different than for women in this way. It's a good tight squeeze for me, but for a strong man, it would certainly not be. Isn't it interesting what we glean when we grow up doing things with our elders? STuff like this, I never would have thought to mention if I were telling someone, but I just "know" how tight it should be. Kinda like spark plugs or lug nuts. You just learn to "feel."

Feral, you do a lot of steps my mom and grandmother never did (heating the lids, etc.) We boiled the jars, but that was to get them sterile. This is really interesting.

ETA: Okay I just saw the part about the "thwock" which is just how it sounds. Missed that the first time through. Lotta info in this thread and the pressure canning thread. My mom was old fashioned I guess. If the jar did not either "thwock" or show an obvious dent (only one now and then would fail) she'd use it immediately and not wait. She didn't trust that seal without the thwock or the dent.

Dang, this makes me want to can, but this year I didn't even get to do a garden.

Kitties

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