Thursday, June 23, 2022

How to Sterilize Canning Jars

Learn how to sterilize canning jars before canning.  Sterilizing your jars can help prevent bacteria and other microbes from growing for a longer shelf life.  However, it's not always necessary to sterilize jars before canning at home.  We will discuss when you need to sterilize jars and the best way to sterilize canning jars.

How to Sterilize Canning Jars

For my canning recipes, I always say to prepare your jars.  This is mainly due to the fact that each of my posts is over 1000 words, and writing about how to sterilize glass jars can add another 500 words!

So today we are going to talk about how do you sterilize canning jars.  We'll discuss when you need to sterilize your jars, when you don't need to, and common methods for how to sterilize canning jars without a canner (and why I don't recommend them).

Once you learn the best way to sterilize canning jars, check out these popular canning recipes:

Do You Need to Sterilize Jars Before Canning?

Surprisingly, you don't need to learn how to sterilize glass jars every time you can.  I was taught to always sterilize my jars after cleaning them, but this isn't the case anymore.

According to the National Center for Home Food Preservation, you only need to sterilize jars if you are water bath processing them for less than 10 minutes.  All pressure canned loads and water bath times over 10 minutes will sterilize the jars as they process.  

Since canning jars need to be sterilized for 10 minutes or more, this can be done while you are processing the food.

You can still pre-sterilize your jars if you want to.  However, this is an extra step and uses more energy (both your energy and the energy to heat the water).

Learn about 11 canning mistakes that can kill you for safe canning.

What Happens if You Don't Sterilize Canning Jars?

If your canning recipe requires that you sterilize the jars, namely for recipes that have less than 10 minutes of processing time, then bacteria and other microbes in the jar can multiply and spoil the food.

For food that is processed for 10 minutes or more, you are safe to skip pre-sterilization.

How to Clean Canning Jars

So if you don't need to learn the best way to sterilize canning jars, then how do you clean canning jars?

Before canning, wash your jars with hot soapy water and rinse well.  I do this for new jars and previously used jars every time I can.  I store my jars in the basement, so I wash them before storing and again before canning.

Then I put the jars in the dishwasher to get them really clean.  

We have well water, so my jars sometimes get a film of minerals on them.  You can remove this by soaking your jars in 1 cup of vinegar per gallon of water.  Let them soak for several hours and rinse well.

When you're washing your jars, it's a good time to visually inspect them for cracks or chipped.  Any cracked or chipped should be taken out of rotation.  I like to set them aside to use for crafts.  Learn how to decoupage with napkins on glass to transform your mason jars.

Do You Boil Lids and Rings When Canning?

No, you do not need to boil the lids or rings when canning.  The rings don't touch the food, so they don't need to be sterilized.

Your grandmother may have boiled the lids, but this isn't necessary anymore.  In fact, you shouldn't boil the lids before canning.  

This is because the coating can melt, causing it to temporarily stick to the jar.  This can create a false seal in canning.  In a few weeks, the lid can pop off of the jar.  Learn about reasons for canning jars not sealing.

You can simply hand wash your rings and lids and set them aside for when you need to use them.  When I started canning, I used to put the lids into hot (but not boiling) water until I was ready to use them.  This is no longer recommend.

How to Sterilize Jars for Jam

Some jam and jelly recipes call for a 5 minute processing time.  Therefore, you will need to find the best way to sterilize canning jars.

You can follow the steps to learn how to sterilize canning jars, or you can simply increase the processing time to 10 minutes to sterilize while processing.

Adding the extra time shouldn't affect the food or the gel, so you can simply add more time to the processing and skip sterilizing the jars.

How Long to Sterilize Canning Jars

If your recipe calls the best way to sterilizing canning jars, you should let them boil for 10 minutes before proceeding with the recipe.

Do Brand New Mason Jars Need Sterilization?

Yes, brand new mason jars need to be sterilized.  They have traveled a long way to get to you, and several hands have touched them along the way.

What is the Best Way to Sterilize Canning Jars?

I like to simply use my water bath canner to sterilize my glass jars.  I already have to fill it with water and heat the water to a boiling, so this is just easier for me.  However, there are several posts on how to sterilize canning jars without a canner on the internet.  I'll discuss below why I don't recommend them.

Sterilizing Canning Jars in Boiling Water

This is the easy way to sterilize canning jars in my opinion.  I have to fill my water bath canner with water and heat to boiling to process, so it's just easier to sterilize my jars this way.

Follow these steps for sterilizing canning jars in boiling water:

  • Hand wash your jars or put them in the dishwasher to clean.
  • Fill jars with water and place in your water bath canner.  Cover with cover.
  • Bring water to a boil and let boil for 10 minutes.  Turn off the heat and let the jars cool in the water.
  • When you're ready to fill the jars, use your jar lifter to dump the hot water from the jar into the canner.  Fill your jars with hot food, place a lid and ring on the jar, and return to the canner.  
  • Add one minute for each 1,000 feet of elevation over 1,000 feet.  

How to Sterilize Canning Jars in the Oven

Many people sterilize canning jars in oven, but it isn't recommended by most jar manufacturers or food safety experts for several reasons.

  • Oven temperatures are not exact.
  • Oven temperature can cycle with periods of heating and cooling.  Therefore, the temperature can vary widely.
  • Oven temperatures are not consistent throughout the entire oven.
  • You'll need to maintain a certain temperature for a length of time to get rid of bacteria, and this just isn't possible in an oven.
  • The dry heat from an oven can cause thermal shock for canning jars.  There can be uneven heating and temperature fluctuations that can weaken the glass or break it.

For these reasons, I don't recommend trying to sterilize canning jars in oven.

How to Sterilize Canning Jars in Dishwasher

I can not find any trusted sources saying that sanitizing in the dishwasher is safe.  I do run my jars through the dishwasher on the sanitize setting before canning, but that's more because I store my jars in the basement.

Again, you don't need to sterilize your jars if you are processing for more than 10 minutes in a water bath or if you are pressure canning.

How to Sterilize Jars in the Microwave

Again, I can't find any university or trusted sources saying the sterilizing jars in the microwave is safe.  I think that it would be the same as sterilizing canning jars in oven where the air will not get consistently hot enough or for long enough to sterilize jars.

How Do You Sterilize Canning Jars Recap

So to recap how to sterilize canning jars:

  • Canning jars don't need to be sterilized if you are water bath processing for 10 minutes or more or pressure canning for any length of time.
  • Jars only need to be sterilized first for processing times less than 10 minutes.  However, you can add 5 minutes to jam or jelly processing times to sterilize the jar at the same time.
  • You do not need to sterilize lids or rings.  In fact, boiling lids can cause a false seal.
  • Using the oven, microwave, or dishwasher isn't recommended for sterilizing because the air does not get hot enough or for a long enough time to properly sterilize the jars.
  • You will need to wash jars in hot soapy water and rinse well before sterilizing or canning.
  • If you do need to sterilize your canning jars, bring them to a boil in water for at least 10 minutes.
  • You will still need to heat your jars before adding hot food to them and placing them in hot water in the water bath.  

Now you know the best way to sterilize canning jars and how to can safely.  For more information about canning, check out my canning supplies for beginners to see what you need to get started.

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