Expert: Carol Schlitt - 1/21/2005

Question
Hello.

I would like to know in details how to sterilze jars, especally for home made jams. I found some info on the net but it seemed to be partial. I would like especially to know how much to fill the glass and what to do with the air trapped in the jar. Does it matter anyway if some air get trapped in the jar after I close it?

Thank you for your help.

Gal

Answer
Hi Gal,

Sterilizing jars is really easy and is something you do before pouring in the food -- such as jam.  Simply place the clean jars in a large pot with water covering them. Boil the jars for 10 minutes. While the jars are boiling you can prepare the jam.  Turn the water off on the jars and allow them to remain in the water while you finish preparing the jam.  When the jam is ready to pour into the jar, remove the jar from the water with tongs or jar lifter, allowing the hot water to drain back into the pot. Fill the jar with jam, leaving 1/2-inch headspace. Wipe the rim with a clean towl. Place a prepared flat (read the instructions on the carton on the flat to see how to prepare -- most today only require heating to simmer and keeping warm while the jars/jam are being prepared)on the jar rim.  Also, most flats do not need to be boiled -- in fact boiling them may destroy the rubber adhesive on the flat causing a seal failure. Then secure the flat with the screw band -- do not over tighten as this may also cause seal failures.

Since you have placed the jam/jelly in a sterilized jar, you only need to process it for 5 minutes in a boiling water bath. Start timing for the boiling water bath after the water returns to a boil. Carefully remove the jars after 5 minutes and place on a towel. Allow to stand at room temperature for 24 hours. Check to see if the jars sealed.  If so, they can now be successful stored in a pantry.  If a jar did not seal, place in the refrigerator and use first.

For a great website on home canning, please visit:  http://www.uga.edu/nchfp/  This is the national Center for Home Food Preservation at the University of Georgia.

If you have more questions, please let me know or you can always contact your local Cooperative Extension Service.

Happy Canning!

Carol C. Schlitt
Extension Educator, Nutrition and Wellness
University of Illinois Extension