Unripened limes tend to be dry and lack flavor, so your marinades, cocktails and savory dishes will lack that oomph. Limes don't ripen off the tree; they must be picked and stored when they are at or close to maturity, but quality differences still exist. When choosing a ripe lime, let aroma, color, weight and texture guide you toward mature fruit.
Smell the limes. A ripe lime will smelly lime-y; those that are underripe will not have a strong smell. Scratch the skin of the lime with a fingernail, then sniff to test for ripeness.
Go green: green limes are generally ripe and have more lime flavor than yellowish-green ones.
Feel the skin. It should give a little when you squeeze it but still firm, not soft. Limes that don't give to a squeeze are under-ripe; those that feel too soft are too ripe.
Choose fruits that feel heavy, since these have more juice than those that feel light for their size. The heaviness also indicates maturity, notes food scientist Shirley Corriher.