If you just bought a jar of jam or jelly, Nicole Richard, a research associate and food safety specialist at the University of Rhode Island's Food Safety Outreach
and Research Program, says you can keep it in your kitchen cabinet until you open it. Homemade preserves in sealed jars can be kept at room temperature.
However, after the jam or jelly has been opened, it is recommended to keep it refrigerated. This, according to Richard, inhibits mould and yeast from forming
Open jams and jellies will spoil faster if they are not refrigerated.
"Refrigerating unsealed jams and jellies reduces the growth of spoilage microorganisms, extending the shelf life of the product."