What Sets Key Limes Apart From Standard Limes?

"It's nothing but limes now," and that's not just according to the littlest of Louisa May Alcott's "Little Women," Amy March. Limes can be found squeezed into a fresh margarita, or made into a creamy curd. They're the perfect fruit for summer (or for those dearly missing summer), thanks to their sweet, tangy flavor. However not all limes are alike. And on your sojourn to the grocery store you might've come upon a bag of small, round limes called key limes. So what are these limes, and what makes them different from your standard lime?

Key limes are a variety of lime named for the Florida Keys. The limes did not originate in the Florida Keys, though there was once a popular commercial key lime crop in the area. They are much smaller than standard limes and have more seeds. The skins of key limes are also thinner, and turn yellow when ripe. In terms of taste, key limes tend to be more floral than their larger counterparts and have a slightly bitter taste. Of course this is just one of the many differences between the two limes. So let's dig into the pulp of it.

Now, you're not all that likely to mistake a key lime from your standard lime. Key limes tend to be much smaller than the standard, or Persian, lime, measuring around one to two inches, while standard limes tend to be about three inches in size. But besides the obvious, surface level differences, what sets the two citrus fruits apart?

Key limes tend to have a very thin skin, unlike standard limes, which can have a thicker skin. This makes key limes much less hearty and shelf stable. For this reason, it's important to keep them in the fridge, rather than the counter as you would with standard limes. Key limes also have more seeds than Persian limes, a fact important to keep in mind especially when cooking with the fruit.

Perhaps the biggest difference between the two fruits is in their taste. Key limes tend to have a more floral taste while standard limes are more acidic and sour. Meanwhile, key limes are much more subtle and aromatic, while still having the tangy edge signature to all citrus fruits.

For most diners, there is one dish that comes to mind when key limes are mentioned: key lime pie. The dish, which is Florida's state pie, is a delicious mixture of key lime juice, egg, sweetened condensed milk, with a buttery graham cracker base. There are, of course, many imitators of the dessert. Some recipes use regular limes or lemons. However, these are a pale imitation of the real thing. This is because key limes give the pie a complex, floral, and tart flavor that offsets the super sweet base, something that standard limes simply cannot imitate.

This doesn't mean that there isn't a time and place for both varieties, it's just important to know when and where to use each. Because of its tart, very acidic flavor, standard limes are great in recipes that require a sharp flavor without the underlying bitterness that comes with key limes. So you would probably opt for standard limes in a margarita, for example (though a key lime pie margarita might be a fun and novel twist). Standard limes are also great for recipes that require a stronger level of acidity, such as ceviche or pico de gallo. Meanwhile, key limes can work better in certain baked goods such as cookies, pies, and cakes, which can benefit from the sweetness of key limes. However, this is all just general guidance. You can choose whichever lime you please.