What will happen if you substitute regular limes in Key lime pie?
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The Difference Between Key Limes and Regular Limes
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They say you should eat several servings of fruit every day. And lime is a delicious citrus fruit. So, when you're craving a slice of Key lime pie, there's no reason not to give in. Right? Right!

Key lime pie is a dessert prepared with lime, of course, as well as egg yolks, and sweetened condensed milk. The pie can be served plain, but many prefer it with an egg white meringue topping, or with whipped cream. It can also be baked in a traditional pie crust, in graham cracker crust, or with no crust at all. It all depends on the baker's preference.

What is Key Lime?

Named for the Florida Key limes used in the original recipe, Key lime pie is a Southern classic and has even been declared the official Florida state pie. Though the lime is strongly associated with the Florida Keys and its popular name even comes from said association, Key limes are actually native to tropical Southeast Asia. Its other names include West Indian lime, bartender's lime, Omani lime, or Mexican lime. And, in the Philippines, it is called dayap or bilolo.

Key limes have not been grown commercially in the United State since 1926 when a hurricane devastated Miami, Florida, as well as the Bahamas and the Gulf Coast. The storm wreaked catastrophic damage on commercial lime crops in the Florida Keys. The crops were replaced with thornless Persian limes, which are hardier than Key limes. As such, Key limes are now imported from Central or South America.

So what happens if you're hankering for a slice of that sweet-tart Key lime goodness, but haven't made it to the Florida Keys to stock up on their local limes? Can you just run to the Piggly Wiggly for a regular lime instead? Does a lime pie made with Piggly Wiggly limes just not have the same élan as Key lime pie? Will people snub your pie at the potluck if you make it with the supermarket variety?

Key Limes vs. Persian Limes

Key limes tend to be small and seedy, with a distinctive lime flavor that is tart, but not too acidic. They also have a very distinct aroma, far more aromatic than common limes. Grocery store limes, generally speaking, are Persian limes, the most widely commercially cultivated variety of lime. They are larger and more tart than their Florida cousins. Persian limes are actually a hybrid cultivated from Key lime and lemon, and they are also known as seedless lime, Bearss lime, and Tahiti lime. Key limes are smaller and contain more seeds than Persian limes. And while Persian limes have thick, bright green skin, a Key lime's skin is thin and tends to be a little on the yellow side. The juice from Key limes is also more yellow.

As for whether they have a different taste—significant enough to be able to tell the difference when used in your homemade lime pie—the food testing pros over at Cooks Illustrated claim that there's a slight difference in flavor. "Sampled plain, the Key lime juice tasted slightly less tart and bracing than its Persian counterpart," they write. They have even gone so far as to run a lab test on the lime juices, confirming that the juice from the Persian limes has a lower pH and higher acidity than the Key lime juice.

That distinction held true when they whipped up a batch of Key lime bars, too. They found that the bars made with Persian limes were more tart than those made with Key limes. Of course, this isn't that significant of an issue for some. Plenty of people like a dessert with a bit of bite and will appreciate the extra acidity that comes from Persian limes.

The main difference seems to be that it requires a lot more of that aromatic Key lime juice to make the famous pie sing. It is worth the elbow grease, though, to get that true floral Key lime flavor—unless, of course, you can't find Key limes. Then just swap them out for whatever you find at the grocery store and dig in because you want to get your recommended servings of fruit, don't you?