variety of homemade jams in glass jars - Stephaniefrey/Getty Images Fresh fruit is a natural treat, but when it's converted into a spreadable, sweet-tart jam, there's almost nothing it can't do.

My grandmother used to make jam every year out of the summer bounty of berries. It was a multi-day project involving scorching-hot vats of berries, thickened by pectin and pounds of white sugar, which ...