Did you know you can steam sterilize square glass jars easily at home in your microwave? Not many people may realize this, or they might think special chemicals or equipment are required to complete the process. In fact, this procedure could be used on any glass container, jar, baby bottle, salad carafe, or any other glass items you have in the house that you want to sterilize. The steam reaches high enough temperatures to kill bacteria and sterilize the jars.
All that is required is a large microwave safe dish with a steam tray insert and lid. It is recommended you first wash and rinse the square glass jars, using dish soap and warm water, regardless of whether you just purchased them or are reusing them, to remove any leftover food particles, dust, or other such deposits. After the jars are rinsed off, you can place them directly into the steam insert. Fill the bottom of the dish with about an inch of water, while making sure it does not touch the bottom of the insert. Place the lid on top over the jars and place the dish into the microwave. The lid should be able to close without any restrictions.
The amount of time needed to steam sterilize your square glass jars in the microwave does vary, from model to model. Start by setting the time to 5 minutes on high power for the first cycle. At the end of this cycle the water has to be boiling, and steam should be rising through the insert. If not, add a few more minutes until you reach this stage. Once you can see the steam, set the microwave to run for another 5 minute cycle on 60 percent power to complete the sterilization process, as the water only has to maintain a simmer to keep creating steam. At the end of the cycle, leave the jars in the oven for another five minutes before removing. Allow the jars to completely cool to a safe temperature in the dish before handling.