Canning is the new kid on the food preserving block. It's been around for just over 200 years, but due to it's mass production capabilities and long shelf life potential, its become a mainstay in modern grocery store and kitchen culture.

Home canning is a process by which foods are placed in jars and heated to a temperature that destroys microorganisms and inactivates enzymes. This heating and later cooling also forms a vacuum seal which prevents other microorganisms from re-contaminating the food.

There are two popular home canning methods: Boiling Water Bath Canning & Pressure Canning.

Boiling water bath canning is the simplest (and least expensive) of the two methods. It requires very little specialized equipment and is a cinch to do. The only downside to this process is the fact that it can only be used to preserve high-acids foods (with a pH less than 4.6) like whole fruit, jams, spreads, preserves, jellies, and pickled vegetables. It is the acidity of each jar's contents - even more than the heat of this canning process - that safely preserves the food. Though both the heat and the acidity are imperative to the ultimate safety of the canned food.

Pressure Canning involves specialized and somewhat expensive equipment, but once you invest, it will allow you to can foods with low acidity (a pH more than 4.6) that need sterilization under high temperature (116-130 °C) - foods including meats, fish, poultry, vegetables, and all low acid foods. So it's less limiting food wise, but a more complicated process this is limiting pocket book wise. :)

There are pros and cons to both methods. I will only be covering boiling water bath canning in this class, as it's a great starting-off point to get familiar with the canning process and the steps that are necessary to ensure safe preservation. If you find you enjoy canning and want to move on to other foods, then investing in a good pressure canner will make sense. :)

Step 1: Why This Method Works

This method keeps spoilers at bay using a combination of:

Heat (from the boiling water bath) to kill microorganisms and slow down the enzymes.
Acidity (from the food itself) to create a hostile environment for the spoilers.
A vacuum seal that keeps new microorganisms from being able to get in and contaminate the food.

When done properly, this preservation technique gives high acid foods 3 fold protection against spoilage and keeps them edible for up to a year (officially) and sometimes even longer. I've read stories of canned goods being found aboard sunken ships from the late 1800's that when opened and tested by scientists have still been microorganism free!

Of course please don't keep your canned goods for that long before eating them (stick to 1-2 years), but know that when done right, this method for putting food by is very safe and effective.

A NOTE ON SAFETY

There are differing opinions out there on what is safe and what isn't when it comes to canning. Without any intention of insulting what might be your Grandma's way of doing things, please DO NOT do the following:

Do not use your oven or dishwasher to sterilize your canning jars. Neither of these techniques are as effective as processing them in boiling water for 10-15 minutes. It's not worth the risk.
Do not use a paraffin wax seal as a substitute to properly precessing your jars of food in a boiling water bath. Without the proper processing time in boiling water, there's no guarantee that the spoilers will be put in check. Also, it's impossible to test for a perfect seal using this technique. Just say not to this petroleum derivitive

Step 2: Botulism & Why It’s No Friend of Yours

A necessary safety announcement about a real, but easily avoided concern:

Clostridium botulinum is the bacterium spoiler that is responsible for botulism poisoning, a very serious and sometimes deadly illness. While the microorganism itself is killed at the temperature of boiling water, its spores are tougher and can survive the boiling water bath process. The other bummer about these small jerks is that they thrive in anaerobic (airless) environments. So a vacuum sealed jar of food that was only heated to the temperature of boiling water is the perfect place for them to grow and proliferate, creating the botulism toxin.

This is where the necessity for using only high acid foods for the boiling water bath canning process comes in. The spores cannot survive in high acid (low pH) environments. That is why is it is VERY IMPORTANT that you never try to can low acid foods using this process. As I mentioned earlier, low acid foods MUST be pressure canned, which can process jars at a much higher temperature than that of boiling water. Neither the bacteria or the spores of Clostridium botulinum can survive those higher temps.

Now for a sigh of relief:

All the recipes in this lesson use either high acid foods or properly acidulated (high acid liquids added) low acid ones and are perfectly safe. My intent isn't to put you off canning with this scary news flash (because safe boiling water bath canning is very easy to achieve), I just want to reiterate the important role that food acidity plays in canning safety.

Boiling Water Bath Canning + high acid foods* = safe canning
Pressure Canning + low acid foods = safe canning

*I will go into more detail later about how to identify high versus low acid foods.

Step 3: Altitude Chart & Formula

To satisfy the heat component of a safe canning process*, jars of food MUST be processed for each recipe's prescribed amount of time in BOILING water.

*The acidity of the ingredients and the vacuum seal created during processing are the other major players.

FUN SCIENCE FACT: Water boils at different temperatures depending on altitude. The higher the altitude, the lower the atmospheric pressure, which means water will boil at increasingly lower temperatures the higher the altitude.

Most people live within 0 - 1000 feet above sea level. Within that altitude range, water boils at 212°F / 100°C. Standard boiling water bath recipes will assume that you live within this range and that your water boils at 212°F.

If you live at a higher altitude, you MUST adjust your processing time to make up for your lower boiling temperature, to ensure that any microorganisms (spoilers) in the food will be eliminated.

The following chart will provide all the info you need to properly (and safely) adjust your boiling water bath processing times for higher altitude living.

FOR EXAMPLE: The canned peaches we'll be making in this lesson call for a processing time of 20 minutes for pint jars. If you lived at an altitude of 3500 ft, your processing time would be 25 minutes. If you have any trouble calculating your processing adjustment, just let me know and I'll be happy to help!

Step 4: Tools & Equipment

General Tools:

Cutting board
Paring knife
Colander
Shallow glass or ceramic bowl
Measuring cup
Slotted spoon
Ladle
Kitchen towels
Large non-reactive pot (not aluminum or copper)
Scale
chopstick or steak knife

Canning Specific Tools:

canning pot w/ round jar rack
pint jars w/ rings and brand new lids
half pint jars w/ rings and brand new lids
canning funnel
lid lifter
jar lifter

Step 5: What Foods Are Best (and Not at All) Suited to This Method of Canning

The only foods that are recommended to be canned using the boiling water bath method are those that are high in acid (food with a pH lower than 4.6):

most whole fruits
fruit-based jams, spreads, preserves and jellies
tomatoes with added acidity
certain vegetables that have been combined with high acid liquids like a vinegar brine for pickling

There are of course always exceptions to a rule, and in this case, that is when low acid foods like cucumbers and carrots are combined with high acid vinegar to create the low PH required for safe boiling water bath canning.

NOTE: The lower the PH the more acidic a food is. The higher, the more alkaline. There are PH test strips and even more precise digital testers that can help you determine the acidity of a food you want to can, but the following is a general rule to follow for what is, and isn't, appropriate canning with this technique.

Foods that you should NEVER BOILING WATER BATH CAN are:

meats
fish
poultry
lentils and beans
non-pickled vegetables
all low acid foods

It's the acid in high acid foods that works in conjunction with the boiling water bath canning temperatures to create a safe food product. The lower temperatures of WB canning as opposed to the higher processing temperatures of pressure canning, are not enough on their own to keep the spoilers at bay. The acid must be present for this technique to work safely.

Step 6: How to Can Using a Boiling Water Bath

Here's a bullet point run down of the boiling water bath canning process with a few notes and how to's added in.

Please try not to feel overwhelmed by this long list and just give it a quick read. Both of the recipes in this lesson illustrate the process clearly, but this can act as a quick reference guide if needed. (I've included a printable pdf of this list for even easier countertop reference.) :)

Fill your canning pot with water, put it on the stove and set it to boil. It can take up to a ½ hour for that much water to heat up, so that's why I've made this the first step.
Add a round rack to the pot.
Wash the jars you'll be using well and submerge them in the canning pot water.
If the recipe you're using calls for less than 10 minutes of processing time in the boiling water bath, you need to sterilize the jars. This is done by leaving the jars in the water once it's come to a full boil for at least 10 minutes. Once the 10 minutes are up, you can remove the jars and fill them with the recipe's food. I'll go over sterilizing the jars in more detail at the end of this list.
Lay one kitchen towel next to the stove to place the hot filled jars on when they come out of the pot. Place another towel in an out-of-the-way spot where the jars can remain undisturbed for 12 hours post canning.
Set out all your tools.
- shallow heat-proof bowl with the sealer lids spread out (unstacked) in it
- lid lifter
- jar lifter
- lid rings
- slotted or un-slotted spoon
- ladle (if necessary)
- wide mouth funnel
- chopstick or steak knife for removing air bubbles from the inside wall of the jars before lidding
- paper towels to wipe the jar rims before lidding
Follow the recipe to create the food filling.
Once the filling is ready, use the jar lifter to remove the jars from the hot or boiling water of the canning pot, emptying them before placing them on the kitchen towel you set out. Pour enough water from the last jar onto the lids in the shallow bowl to soften the sealing compound. (DO NOT BOIL THE LIDS!) Pour the rest of the water back into the canning pot and set the jar on the towel. NOTE: You should never boil the sealer lids. This could damage the sealing compound. Adding just boiled or simmered water is fine though.
Place the canning funnel in the first jar and use the spoon or ladle to transfer the food into the jar. Keep the spoon as low as possible so that you don't introduce unnecessary air bubbles into the food. If you're adding whole fruit, pack it in tightly and leave 3/4" headspace. When adding the liquid that follows, fill it so that there is 1/2" headspace. (Headspace is from the top of the food to the rim of the jar.) If you're adding a preserve, jelly, or jam, leave 1/4" headspace.
Run the chopstick or plastic knife around the inside of each jar to remove any large air bubbles. (Small ones are ok.)
Use a damp paper towel to wipe the rims of the jars.
Using the jar lifter, remove a sealer lid and place it on the jar so that it's centered and the sealing compound lines up with the rim.
Add and gently hand-tighten the lid ring. Don't tighten it too much, as air needs to be able to escape the jar during processing in order to create the vacuum seal.
Repeat for the remaining jars.
Use the jar lifter to carefully place the jars into the canning pot so that they aren't touching each other or the sides of the pot. You want the water to cover the jars by 1-2 inches. If the pot has so much water that it's in danger of overflowing, remove some of the water. The 1-2 inches of water above the jars is necessary, but more than that isn't, as it would just have the potential to bubble over as it processes.
Set your timer to the processing time suggested in the recipe (plus any additional minutes necessary if you live at an altitude above sea level. See the chart in the next step for how to calculate this.). Once the water returns to a boil, hit start.
Once the jars have processed for the correct amount of time according to the recipe, use the jar lifter to carefully remove the jars, keeping them level, and set them on the 'out of the way' towel.
After one hour, it's important to check to see if the lids sealed properly. There are two ways of doing this:
- Press down on the center of the lid with one finger. If there's no give in the lid, it is sealed. If it pops down and then back up again, it hasn't sealed.
- OR remove one of the lid rings and using the tips of your thumb and fingers, grab hold of the edges of the sealing lid and try to lift the jar a few inches off the table. If the lid is sealed properly, the jar will easily lift up by the lid. If it isn't, just the lid will lift off.
  *Test each jar using either technique. Any jars that didn't seal properly must go immediately into the fridge and be eaten within 3-4 days.
Let the jars set for 12 hours on their towel before moving them to the cupboard or pantry.
Eat them within 1 year.

Boiling Water Bath Canning Step By Step List.pdf
Download

Step 7: Preparing Your Jars for Canning

Remember, cleanliness is one of the important names of the 'spoiler control' game, so taking the time to properly prep the jars is a necessity.

If the recipe you're using calls for a canning processing time of 10 minutes or more, you do not need to sterilize your jars, but they must be clean. If the recipe you're using calls for has a canning processing time that's under 10 minutes, you must clean and sterilize the jars before filling them.

Before adding the hot food to the jars, you also need to heat them up by letting them sit filled with warm or hot water - and dumping out the water just prior to filling them. This prevents cracking due to heat shock from the hot food.

Ok, here's the prepping how-to:

Wash all the jars and sealing lids you plan on using in warm soapy water with a clean cloth or sponge.

Set them on a clean towel, but do not towel dry them.

Fill the canning pot with water and submerge the jars (without lids) in the cool water. Turn on the burner and bring the water to a boil. If you don't need to sterilize your jars, follow all the below instructions but skip the 15 minutes boiling time.

To sterilize the jars: The water must be completely covering the jars. Once the water returns to a full roiling boil, set your timer for 15 minutes.

Once the timer goes off, use the jar lifter to remove the jars, still filled with water, and place them on a kitchen towel next to (but a safe distance from) the pot.

Use the water from the last jar to fill the shallow bowl that contains the sealer lids. The hot water will soften the sealing compound.

Refill that last jar with water and set it to join its friends.

Leave the jars filled with the warm water until just before you're ready to fill them with food.

And that's how to properly prep jars for canning!

Step 8: Project #1: Whole Fruit Canning

One delicious way to practice what you've learned is to try canning whole fruit! My Canning Fruit instructable (link below) will take you step-by-step through a canning recipe that does not require sterilized jars due to it's cooking time being longer than 10 minutes:

Canning Fruit

Step 9: Project #2: Raspberry Spread

Another recipe to try, is this delicious raspberry spread! Because its cooking time is less than 10 minutes, you get to practice sterilizing the jars! Click on the link below to give this one a go:

Raspberry Spread

Step 10: Storage Tips

Once your precious jars of preserved yumminess have cooled and sat in place for 12 hours, move them to a dark, cool cupboard, pantry, or root cellar. There they will keep for up to 1 year, but once opened, must be kept in the fridge.

Step 11: Quiz Time!

{
    "id": "quiz-1",
    "question": "What kind of foods are ok to can using the boiling water bath method?",
    "answers": [
        {
            "title": "Low pH foods",
            "correct": true
        },
{
            "title": "High pH foods",
            "correct": false
        }
       
    ],
    "correctNotice": "That's correct! Low pH means high acidity, and that acidity must be present in all foods that get boiling water bath canned. It's a matter of safety.",
    "incorrectNotice": "That's incorrect! Try again."
}

{
    "id": "quiz-2",
    "question": "What is the easiest way to discover whether or not you've canned your foods correctly?": [
        {
            "title": "Put the jar to your ear and listen, to make sure you don't hear any air leaks.",
            "correct": false
        },
{
            "title": "Shake the jars to make sure the lid doesn't pop out.",
            "correct": false
        },
        {
            "title": "Remove the lid ring and lift the jar by the edges of the lid to confirm that there's a strong seal.",
            "correct": true
        }
    ],
    "correctNotice": "That's correct! This is the simplest and BEST way to make sure a strong seal was created during the boiling water bath process. This ensures that your canned goods will be safe to eat even after months in the pantry.",
    "incorrectNotice": "That's incorrect! Try again."
}