The Key lime is a citrus hybrid with a spherical fruit, 2½ – 5 cm (1 – 2″) in diameter. The Key lime is usually picked while it is still green but it becomes yellow when ripe.
It is smaller and seedier, with a higher acidity, a stronger aroma, and a thinner rind, than that of the Persian lime. The Key lime is valued for its unique flavour compared with other limes. The name is derived from its association with the Florida Keys, where it is best known as the flavouring ingredient in Key lime pie. It is also known as West Indian lime, bartender’s lime, Omani lime, or Mexican lime, the last classified as a distinct race with a thicker skin and darker green colour. Philippine varieties have various names, including dayap and bilolo.
Difference Between Limes & Key Limes
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 a regular Persian 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 table-tennis ball — about 2½ cm – 3 ¾ cm (1 – 1½”) in diameter. Persian limes are also heftier than key limes, weighing in at around 90 g (3 oz.), whereas key limes are a featherweight 30 g (1 oz).
Flavour and Aroma
While key limes and Persian limes are similar in flavour, 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 flavour 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.
How to Keep Limes Fresh
- Uncut limes can be stored in your pantry for up to a week and three weeks in the refrigerator. If you have cut limes, they should be stored in the refrigerator.
- Place whole, uncut limes in the crisper of your refrigerator in the original plastic that you bought them in at the grocery store. Refrigerated whole limes will last for about two to three weeks. You also can place them in the crisper without the bag. If you do not want to put your limes in the fridge, place them in a bowl in your kitchen away from direct sunlight and at room temperature. Outside of the fridge, the limes should last for about a week.
- Cut a small square of the plastic wrap. If you have a bunch of lime slices, wrap each lime slice individually in a small piece of the plastic wrap. Then place the wrapped limes in a plastic, ziplock bag. Place the bag in the refrigerator, and they should keep for up to five days.
- Freeze fresh lime juice by pouring into ice cube trays. Freeze the lime cubes, and when they are completely frozen, remove the cubes and store in a ziplock plastic freezer bag in the freezer. Grate the fresh lime zest and place in a zip-top freezer bag and place in the freezer. Both can be easily thawed when they need to be used.
Key Lime Juice Substitutes
When choosing a substitute for Key lime juice, carefully consider the role that this ingredient is intended to play in the finished dish or drink. Whether one substitute is superior to another depends on the context in which it is being used. Key lime juice is used in cocktails, curries, dressings, fruit drinks, jams, jellies, marmalades, marinades, syrups and desserts. Key limes are also known as the “bartender’s limes,” because their bright, tart flavour enhances a number of beverages, including mojitos, caipirinhas, margaritas, and gin and tonics. Key lime juice finds its fullest expression in Key lime pie, a creamy custard pie that showcases the fruit’s distinctive flavour.
- When substituting Persian lime juice for Key lime juice, use a bit more than the recipe calls for, because Persian lime juice has a far less potent flavour than Key lime juice. To compensate for this, cut back on other liquids in the recipe accordingly. Bear in mind also that Persian lime juice is not as sour as Key lime juice. You may want to add a few drops of lemon juice to your recipe to make up for this.
- Rose’s lime juice is best substituted for Key lime juice in cocktails. To balance the flavours in the drink, reduce other sweet ingredients to taste. If you are making a drink that isn’t intended to be sweet, such as a gin and tonic, substituting Rose’s lime juice is not recommended unless you think you would enjoy the extra sweetness. Rose’s lime juice may be substituted for Key lime juice in other sweet recipes as well.
- If you happen to have access to calamondin juice, it makes a fantastic substitute for Key lime juice in almost any recipe, because their flavours are extremely similar.
- If you’re desperate for a Key lime juice substitute, lemon juice can be used. Use a ratio of 1 cup lemon juice for every ⅔ cup Key lime juice required by the recipe, and adjust other liquids accordingly.
- Passion fruit juice isn’t sour, so it shouldn’t be substituted if you are making a recipe that you wish to be sour. However, switching passion fruit juice for Key lime juice in cocktails and desserts has become increasingly popular. Passion fruit juice adds great colour and aroma to any drink or dish.