There is nothing like a tangy-sweet slice of key lime pie. But if you are fresh out of key limes, do not make the mistake of trying to substitute regular lime for key lime in a recipe. As much as key limes appear like tiny versions of their relatives, there are quite a few differences that can impact your recipe.
If you have ever seen a key lime (Mexican or West Indian) next to a regular lime (Persian or Tahitian), the difference is obvious. While Persian limes tend to be just smaller than a tennis ball, diminutive key limes are more the size of a ping-pong ball -- about 1 to 1 1/2 inches in diameter. Persian limes are also heftier than key limes, weighing in at around 3 oz., whereas key limes are a featherweight 1 oz.
Flavor and Aroma
While key limes and Persian limes are similar in flavor, key limes pack a bigger punch of acidity in their small package. Key limes are valued for their "bouquet," or complex aroma, and are widely used around the world to garnish and flavor seafood dishes, add a tangy twist to beverages and impart a zesty quality to otherwise sweet desserts. You can use key limes in salad dressings, drinks, Mexican dishes like guacamole, Thai-inspired chicken dishes or even a ceviche -- raw fish "cooked" by the acid in the lime juice.
Key lime trees are as small and squat as the key limes they produce. Rarely growing taller than 12 feet, key lime trees tend to be small and bushy with very thorny branches. Leaves are small and pale green with rounded-off tips. Persian lime trees are taller, reaching up to about 15 feet in height, and have no thorns, making harvesting an easier prospect. Their leaves are bright green and serrated.
History of Limes in the U.S.
The United States is the worldwide exception in its preference for the larger Persian limes -- the rest of the world prefers the diminutive key limes, instead. The reason for this can actually be traced back to a natural disaster. Up until the early 1900s, key limes were widely cultivated in Florida, but a hurricane in 1926 wiped out the majority of the key lime crop. When the gun-shy farmers replanted, they opted for hardier and more disease-resistant Persian limes, and a new preference was born.