If there is an epicene, all-encompassing term for the shivering, shimmering stuff with which we adorn sandwiches, toast, and other baked goods, then it is not “jam,” not “conserves,” not “preserves,” not “fruit spread” or “spreadable fruit,” but “jelly.” Although some dialectal variations can be found, ask most English-speaking Americans what fruity concoction they smear on bread with peanut butter, and “jelly” is the answer that will come back. (If “spreadable fruit” is the reply, run. You’re talking to a cyborg.)
Jelly is mostly made up of gelatin, pectin, or some other gelling agent that is added to fruit that has been cooked until it is soft and its solids have been strained out, often to transparency. The word came into English in the late fourteenth century by way of the French gelée, “frost,” and ultimately from the Latin gelata, “frozen,” which, of course, gives us the name of that wondrous Italian treat called gelato, and in that hoary sense it can be likened to a glacier—well, a slow-moving syrup, anyway, a term that comes to us by a circuitous path from the Arabic sharàb, “wine.” John Keats gets at this distinction in his poem “The Eve of St. Agnes”:
While he forth from the closet brought a heap
Of candied apple, quince, and plum, and gourd;
With jellies soother than the creamy curd,
And lucent syrops, tinct with cinnamon
The word “jam,” which dates to the early eighteenth century, probably does not come from the French j’aime, “I love,” as one contemporary author guessed, but instead from the English verb that means “to press” or “to squeeze.” Jam is cooked like jelly, but the fruit solids are pureed or mashed and kept in the mixture. These solids give the concoction opacity and substance, so that the cook needs to use less pectin or gelatin, even dispensing with a gelling agent altogether.
Preserves similarly contain cooked fruits, except that the fruit solids are left in chunks rather than pureed. This gives the concoction not just substance but heft. Conserves are preserves made of mixed fruits instead of single strains of, say, plum or peach, though this very fine distinction is seldom observed. And marmalade is a kind of preserve that includes the peel as well as the cooked fruit. The word comes from the Portuguese marmelo, “quince,” kin to the apple, though most marmalades are made of citrus.
All this parsing conjures up orchestra leader Glenn Miller’s tune “It Must Be Jelly (’Cause Jam Don’t Shake Like That),” which topped the charts in 1944. Miller’s plane disappeared in gelid weather over the English Channel in December 1944, but not before he copyrighted the hit. “It must be jelly ’cause jam don’t shake like that / Oh Mama, you’re so big and fat”: Lyricist Sunny Skylar surely borrowed, as so many writers of the era did, from Harlem street talk, which likened jelly to fat and jam to muscle; there’s a certain lasciviousness to the enterprise, as enshrined in the name of the great jazz man Ferdinand “Jelly Roll” Morton. Miller’s tune makes no fine distinctions about pectin levels, but it presses its point—preserves it, even—all the same.