Jelly Jars being Sterilized in the oven. A full size oven can do a large number of jars at one time, and keep them hot and ready to be filled. You could also sterilize your jars in a Canning kettle. With the MEHU-LIISA, you do not need to process the filled jars in a water bath canner. Just sterilize the lids with boiling water, and bottle the boiling product into hot jars, and cover immediately with the hot sterilized lids.