What can I use instead of key lime in a liqueur recipe?

Expanded Explanation

Regular Persian lime is the easiest substitute for key lime, but the result will usually be slightly less aromatic and a little less sharp. You can bring it closer by adding a small amount of extra zest, since key lime character comes from both strong peel aroma and vivid acidity. In many recipes, this is enough to keep the citrus profile lively.

A mix of regular lime and a touch of lemon can also work when you want more brightness without excessive bitterness. Lemon should be used carefully because it can shift the flavor toward a cleaner, less tropical citrus profile. If the recipe depends heavily on the distinctive perfume of key lime, no substitute will be identical, but a balanced blend can still produce an excellent liqueur.

When substituting, the safest approach is to reduce the initial amount slightly and taste the infusion more often. Different citrus varieties release oils, bitterness, and acidity at different speeds. Adjusting in stages gives better control than trying to force a replacement to behave exactly like key lime.