Key lime pie Period BOrigin theory CVerified

Key lime pie is a cold pie in which the juice of small, fragrant Florida Keys limes sets sweetened condensed milk and egg yolks. A crust of crushed graham crackers holds a cream of condensed milk, yolks, and juice. The trick at work is that citrus acid, not the oven, thickens the milk and eggs: with almost no baking, the acid acts on the proteins in the condensed milk and sets it to a smooth firmness.

The key to the dish is sweetened condensed milk. Patented and put on the market by Gail Borden in 1856, it brought a rich, shelf-stable milk to the warm South, where refrigeration was scarce. Where fresh cream was hard to come by, condensed milk became the base for dessert, and this method of setting a filling with citrus acid makes direct use of that milk's properties.

Still, the arrival of condensed milk on the market did not, by itself, produce the pie. The pairing of key lime juice with condensed milk shows up in print only some seventy years later. In 1933 a Miami newspaper ran a related lime pie; in 1935 an "icebox lime pie" was recorded as a Florida Keys specialty; and in 1940 the name "key lime pie" itself first appears. What began as a home dessert of the Florida Keys was in time carried into tourism as a dish that came to represent the state.

Key lime pie has an origin legend fitting for the Florida Keys. A cook called "Aunt Sally," in the household of the Key West shipowner William Curry (1821-1896), is said to have devised it in the late nineteenth century, or else Key West fishermen made the first version aboard their boats. This is the account given by David Sloan, a cookbook author and co-organizer of a key lime festival.

But no contemporary record for the legend has surfaced. The earliest surviving telling of the Aunt Sally story dates to 1995, in promotional material for a bed-and-breakfast set up in Curry's former house, roughly a century after the invention it claims. Despite an open call for evidence, no reliable source predating 1931 has been found.

The pastry scholar Stella Parks, meanwhile, points to a different first appearance. The oldest form documented in print is a recipe titled "Magic Lemon Cream Pie," in a promotional brochure that the condensed-milk maker Borden handed out in 1931: a graham-cracker crust with an unbaked custard of condensed milk, egg yolks, and citrus juice. Key lime pie is likely to descend from it.

There was once a telling that traced the pie back to 1856. But what happened that year was the debut of sweetened condensed milk, not proof that key lime pie itself was made. What is set aside as folklore is the single claim that a particular nineteenth-century person invented it; that key lime pie took root as a dessert of the Florida Keys stands untouched.