How to Properly Prepare Canning Jars: A Step-by-Step Guide

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When it comes to home canning, properly preparing your jars is essential to ensure safe and successful food preservation. Whether you’re canning fruits or homemade jams, taking the time to properly clean, sterilize, and prepare your jars can make all the difference in preventing spoilage or contamination. Preparing your canning jars is simple and gives peace of mind so you can confidently preserve the harvest. Follow these simple steps in this step-by-step guide to enjoy your homemade goods all year long. 

What is home canning?

Canning as we know it, heat processed food in glass jars, was developed by Nicolas Appert in the late 18th century. During the French Revolutionary War, the French government offered a reward to anyone who could develop a practical method of preserving food that the army could use. After 14 to 15 years of experimentation, Nicolas Appert was awarded the prize in 1810 and became known as the “father of canning”. While Nicolas knew his method worked, he didn’t fully understand the science behind why it worked. 

While the process of canning foods became popular. Other scientists took Appert’s method to the next level, even developing patents in the field. Still, it would be decades before the relationship between microorganisms and food spoilage would begin to be understood.   Today modern methods of canning practices continue to be refined. Methods considered standard practice in the canning world only a few decades ago are no longer considered safe practices. It’s for this reason that there can be conflicting information regarding what methods are safest for home canned foods. 

Why Properly Preparing Canning Jars in Essential?

Properly preparing canning jars is essential to help prevent botulism. While extremely rare, botulism is a potentially deadly form of food poisoning caused by the bacterium Clostridium botulinum. Botulism spores can thrive in improperly home-canned food. While sterilizing your jars may seem like an inconvenience, this step destroys botulism spores that may be present, ensuring that your home canned foods are not contaminated.

When is Sterilization Necessary?

The National Center for Home Food Preservation is the ultimate source for research-based guidelines concerning all types of home food preservation. While the internet can be full of recommended shortcuts or preservation methods that were used in past generations. The NCHFP takes food safety seriously, using scientific data to back up its recommended practices.  If I ever question a food preservation method, I cross-reference the recommendations found at the NCHFP.

When I started canning, sterilizing canning jars was standard practice for most all canning processes. However, continued research led to a significant change in 2015. 

While I choose to sterilize my jars for all water bath canning projects, some home canners choose to process all of their water bath canned foods for a minimum of 10 minutes so that they can skip the sterilization process. 

Admittedly, the guidelines get a little fuzzy when it comes to sterilizing canning lids. Per the manufacturer’s instructions, it’s not necessary to even heat canning lids before use. Furthermore, boiling the lids before use can soften the sealing compound of the rubber-lined metal lid. This can cause seal failure. Even if the jars seal successfully at the time of processing, lids are more likely to fail over time. The National Center for Home Food Preservation defers to the manufacturer’s recommendation. At minimum, its best practice to wash the canning lids before use.

Screw bands never require sterilization since they never touch the food. 

Essential Supplies for Preparing Canning Jars

When sterilizing canning jars the recommended method is to boil them in water for 10 minutes. The water needs to be at a full rolling boil for the entire processing time of 10 minutes. Here are the necessary supplies to properly sterilize canning jars.

• Boiling-water canner or large pot for sterilizing
• Mason jars
• Jar lifter or tongs
• Dish soap and hot water for cleaning

Step By Step Sterilization Process

What About Different Methods?

Many home cooks, use the dishwasher method to sterilize canning jars.  If your dishwasher has a sterilization cycle, then this is an acceptable method of sterilizing canning jars.  Simply running canning jars through the dishwasher on a regular cleaning cycle is not sufficient to sterilize canning jars.

Another popular method is the oven method. Home cooks place washed and wet canning jars in the oven and heat the oven to about 250 degrees. While I do warm jars in the oven for pressure canning, the oven is not a reliable means of sterilizing jars. While you can stick your hand into a hot oven to remove a pan, you simply can not do the same in a pot of boiling water.  Additionally, it’s well known that ovens fluctuate in temperature throughout the baking cycle and often are not calibrated correctly. 

Peace of Mind

While sterilizing canning jars does involve extra time and work, it’s comforting to know that the food you work so hard to preserve will be safe to eat.   For my family, the extra time and effort is worth every minute!