Both Persian and Key Limes have a higher sugar and citric acid content than lemons, and Key limes are more acidic than Persian. The peak season is during the summer, June through August, but they are available year-round from Mexico and Central America. Unless you live in the Florida Keys or are otherwise a Key Lime pie aficionado, in which case only limes grown in the Keys are acceptable as 'Key Limes'. Avoid any signs of decay, mold or blotchy, brown spots. Don't buy if skin is turning hard or shriveled.
Frozen juice keeps for two to three months.
Uses As a Key West resident, I must say first and foremost, Key Lime Pie. They are also delicious in beverages, sorbets, and jams. Nutrition Limes, including the Key Lime, actually contain less vitamin C than lemons. There are also very sweet limes, called appropriately 'sweet limes', which are apparently used mostly in North African and South American cuisines. Oh, one more.