Cooling Jams and Jellies
After the boiling process, jams and jellies should be cooled as fast as possible without breaking the glass. This results in the brighter color and the fresher flavor of the product. Remove the canning rack with jars from the pot and place it on a towel. Do not tight the screw bands. Cool for 12 hours or overnight. It is important not to disturb a jelly while a setting process is in progress, otherwise the jelly strength and texture will be weakened. Using large quart size jars can result in a weaker gel, due to slow cooling.
The canning jars are removed from the canning rack and allowed to sit undisturbed for 12 hours. During this cooling period the gel sets in and the strong seal develops.