Darker green Persian/Tahitian limes and the smaller, yellower Key limes (photo by Evan Dempsey | © THE NIBBLE).
We love the filling of Key lime pie. Not especially a crust fan, we often make the filling alone, to serve crustless in pots de crème or ramekins.
If you’ve had Key lime pie made with fresh-squeezed, as opposed to bottled, juice, you know what an exquisite difference that is. But for many years, Key limes weren’t available nationwide, and then, they were limited to their season of June through August.
So great is America’s love of Key lime pie that the fruits are now available year-round. That means no more bottled juice!
Key limes (Citrus aurantifolia Swingle), also known as Mexican limes and West Indies limes, are grown in the Florida Keys, Mexico and the West Indies. They are much smaller than standard supermarket limes, known as Persian or Tahitian limes (Citrus x latifolia). You can see the relative sizes in the photo. (See all the different types of limes in our Lime Glossary.
About the size of a ping pong ball, the Key lime is rounder and more fragrant than the Persian/Tahitian lime, with a much thinner rind. It has more seeds, and we’ll keep it that way: Breeding out features like seeds tends to breed out flavor as well.
But the real reason people love Key lime is that it’s less acidic than the Persian/Tahitian: pleasantly tart rather than puckery sour. It makes a big difference in a dessert. You can make Key lime pie with regular lime juice, but it will have more tang.
When purchasing Key limes, don’t worry if the skin is more yellow than green, or vice versa. Choose limes that are heavy for their size, which indicates more juice. The limes can be kept at room temperature for several days, or will keep for a week or more in the fridge (keep them in a plastic storage bag or wrap them in plastic wrap).
As a general tip, before you juice limes or any citrus, bring them to room temperature; then roll them on the counter under firm pressure from your hand. This will release more juice from the sacs.
The Key lime, a.k.a. Mexican lime and West Indies lime, originated in neither the Florida Keys nor Mexico nor the West Indies, but in the Indo-Malayan region of southern Asia. It was unknown in Europe before the Crusades and is presumed to have been brought to North Africa and the Near East by Arabs.
It was brought by European Crusaders from Palestine to the Mediterranean countries. In the mid-13th century, the lime was cultivated and well-known in Italy and probably also in France. It was taken to the Americas by Spanish and Portuguese explorers in the early part of the 16th century, where it became naturalized in southern Florida, notably in the Florida Key. It was grown in southern Florida at least since the early half of the 1800s, often as an ornamental yard tree.
By 1883 Key limes were being grown commercially on a small scale. When pineapple cultivation was abandoned in the Florida Keys because of soil depletion and the 1906 hurricane, farmers began to plant Key limes as a substitute crop. Because transporting delicate fruit was iffy in those days, Key limes were pickled in salt water and shipped north, where they became a popular children’s snack. (Remember Amy March in Little Women pining for pickled limes?)
HOW TO USE KEY LIMES
Use them wherever you might use regular lime juice: in cocktails like Gin & Tonics and Margaritas, in salad dressings (including fruit salad, where just a squeeze will suffice), on chicken and fish/seafood, in marinades, sauces and soups.
Replace the ubiquitous lemon bars with Key lime bars. This recipe from My Baking Addition incorporates coconut into the crust (photo © My Baking Addition).
1. MAKE the crust: Preheat the oven to 350°F. MIX the graham cracker crumbs, sugar and butter in a small bowl. Press evenly onto bottom of an 8-inch square glass baking dish. Bake until dry and golden brown, about 10 minutes. Let cool completely on a wire rack. Do not turn off the oven.
2. MAKE the filling: Put the egg yolks and lime zest in the bowl of an electric mixer fitted with the whisk attachment. Mix on high speed until very thick, about 5 minutes. Reduce the speed to medium. Add the condensed milk in a slow, steady stream, mixing constantly. Raise the speed to high and mix until thick, about 3 minutes. Reduce the speed to low. Add lime juice and mix until just combined.
3. SPREAD the filling evenly over the crust with a spatula. Bake until the filling is just set, about 10 minutes, rotating the baking dish halfway through. Remove from the oven and cool completely on a wire rack. Refrigerate at least 4 hours or overnight. Cut into 2-inch-square bars. Ungarnished bars can be refrigerated in an airtight container up to 3 days.
4. MAKE the optional whipped cream prior to serving. Place the cream in the clean bowl of an electric mixer fitted with the clean whisk attachment. Mix on medium-high speed until stiff peaks form. Garnish the bars with whipped cream and serve.