Sterilizing the jars and the lids is a crucial step and should not be skipped or ignored for the best results, here is how to do it:   Sterilizing the jars:  Rinse those, place them upside down on a clean towel, allow them to dry, and then place them in the oven for 10-15 min at 65°C or 200°F. Sterilizing the lids: Before applying the lids and sealing the jam, those also need sterilizing. The way I do it, is I place them in a bowl and pour boiling water over them. Leave them in the hot water for 2 min and then pick them up with tongs and place them on a clean towel (face down for the water to drain. Place on a tray in the oven too. Make sure to wipe clean the rims of the jars before sealing the jars with the lids.