When it comes to sterilizing canning jars, the procedure varies greatly depending on the method of canning and the length of time it takes. If the canning process will take less than 10 minutes, or more depending on altitude, someone using a water bath canning method for jars only needs to sterilize the jars. Sterilization can be accomplished by immersing the jars in boiling water and keeping them clean and warm until ready to use. Canning jars do not need to be sterilized when using a pressurized canner, regardless of the time.
While all canning jars should be cleaned before use, there are some circumstances in which a canner should consider sterilizing the jars. Placing the jars right side up in a large pot, typically the one used for water bath canning, and covering them with hot water is a simple way to sterilize them. To ensure proper sterilization, the water is brought to a boil and kept there for 10 minutes. If you’re sterilizing canning jars at a higher elevation than 10,000 feet (about 3.05 kilometers), add one minute for every 1,000 feet (about 305 meters).
After the jars have been sterilized, remove them from the hot water and set them aside. The jars should be cleaned by hand or in a dishwasher before sterilization. After sterilizing the jars, they should be kept clean and hot until they are ready to use; one of the easiest ways to do this is for a canner to keep the jars in a hot dishwasher until they are ready to use.
After sterilizing canning jars, canners should be careful to keep the lip around the jar’s edge clean while using them. Filling jars with a funnel makes the job easier, and once they’re filled to the right level for canning, the lip should be wiped clean with a rubber spatula and a clean towel. This ensures that the jar’s lid can form a proper seal during the canning process.
Sterilization of canning jars isn’t always necessary, but the jars should be cleaned and kept warm before use. This sterilization requirement is determined by the recipe being followed and the amount of time that recipe requires for the actual canning process. Sterilization prior to canning is typically not required in water bath canning if the recipe calls for the canning process to last 10 minutes or longer once the food is in the jar. However, just like the standalone sterilization process, this time is affected by altitude.
Anyone who uses pressurized canning instead of water bath canning does not have to worry about sterilizing canning jars before using them. They should, however, be thoroughly cleaned and kept warm or hot before canning. Regardless of how long the canning process takes, the high heat and pressure of the canning process sufficiently sterilizes the jars during this type of canning.