Fruits are for eating; lemons and limes are for seasoning, like a pinch of salt or a grinding of pepper—or, perhaps more to the point, a splash of vinegar. Fruits are sweet and seasonal; lemons and limes are sour to the point of puckery, and you would no more expect to find them missing from the grocery store than you would onions or garlic. But those lemons and limes we so thoughtlessly squeeze onto a slab of broiled salmon are grown, not manufactured—no matter what you might think when you see them lined up so perfectly at the grocery. In fact, they qualify as heirloom fruits. The two main varieties of each that are grown today were introduced more than one hundred years ago.
Lemons and limes are thought to have originated in the same part of Asia, but today lemons are preferred in areas where the weather is milder—most of Europe, for example—while limes are preferred where the weather is hot and humid—the Caribbean basin and Southeast Asia.
Lemons are among the most ancient of the citrus hybrids. They probably first appeared in the foothills of the Himalayas, but records indicate that they reached the Mediterranean basin as early as the first century A.D. They were among the fruits spread by the Arabs during their domination of southern Europe. Lemons reached the New World on Columbus’s second voyage, in 1493.
Most of the lemons you’ll find in the grocery store today are either Eurekas or Lisbons. They look pretty much the same—lemon varieties are notoriously difficult to tell apart, even for the people who grow them. The only real clues are that the skin of the Eureka is slightly ridged and a little rougher than that of the Lisbons. The best way to know which type you’re buying is by the time of year. Lisbons, which originally came from Portugal to the United States in the middle of the nineteenth century, are cool-weather lemons and are harvested in the winter and spring. Eurekas were discovered in 1858 in Los Angeles, where they originally sprang from seeds of an Italian variety. They handle the heat better than Lisbons and are picked in the spring and summer, but they can hang on the tree for months after ripening and often are available even in the heart of the Lisbon harvest.
The Bearss, discovered in a Florida grove in the 1950s, is the lemon of choice in the small Florida lemon industry. Of more interest to cooks is the Meyer lemon, which isn’t really a lemon at all, although it certainly looks and behaves like one. It has a sweeter flesh and a more aromatic peel than most true lemons. Discovered near Beijing, China, by a plant explorer named Frank Meyer, it was introduced in the United States in 1908. Until recently, it was believed to be a cross between a lemon and a mandarin, but DNA testing has found that it is really the offshoot of a union between a lemon and a sweet orange. It has wonderful eating qualities, but because it’s so juicy and its peel is so thin and delicate, the Meyer was long regarded strictly as a backyard fruit. It became a favorite of California cooks and farmers’ market growers in the 1990s and is now available nationally as a specialty.
If anything, limes are even more venerable than lemons. Their early history is clouded by a confusion of names. In some Asian and Arabic languages, the fruit is lumped in with lemons and other acidic citrus. We can be reasonably certain that the lime spread west at the same time as the lemon and by the same means—carried along by the Arab conquest and by the crusaders. The story of the modern lime begins in the sixteenth century, when Spanish and Portuguese sailors introduced it in the Caribbean basin. With the ebb and flow of colonization, many lime orchards were abandoned, and the trees were left to nature to sport and cross-pollinate as they pleased. From these Caribbean limes gone wild, two important varieties emerged: Tahiti and West Indian.
In most of the lime-loving world, the West Indian is the preferred variety. It is a small, round lime that is greenish yellow at full maturity, extremely sour, and intensely aromatic and flavorful. It is widely known in the United States as the Key lime and is found today in slightly different versions throughout India, Egypt, Morocco, Brazil and Mexico under various local names. At the turn of the twentieth century, the West Indian lime was just as important in the United States as it now is in the rest of the world. But in 1926 a massive hurricane in southern Florida wiped out the lime orchards, and today this lime grows there mainly as a backyard fruit. These limes also show up in Mexican markets, where they are labeled “Mexican limes.”
The lime that replaced the West Indian in the hearts of American growers was the Tahiti, sometimes called the Persian (though, oddly, there is no trace of such a lime in Iran). The Tahiti is much larger than the West Indian and largely seedless. Although the flavor and aroma of the Tahiti are not as powerful as those of the West Indian, the tree is stronger—resistant to many of the fungi and viruses that afflict the West Indian. It is also much less cold sensitive and does not require as much heat to ripen. Prior to Hurricane Andrew—which in 1992 devastated the area around Homestead, Florida, that was the center of Florida’s lime culture—more than 6,300 acres of the fruit were cultivated in the state. Ten years later, only 800 acres remained. An infestation of citrus canker in 2002 completely wiped out the lime harvest in Florida, and today all of the limes—both fresh and processed—sold in the United States are imported, most of them from Mexico.
Because lemons and limes are valued mainly for their acidity, which decreases with ripeness, they can be picked as soon as they reach minimal size and juice content, rather than at a certain stage of maturity. Fruit that is harvested when it is young lasts longer than fruit left to ripen further. The fruit is then sorted by color according to maturity and cured in a controlled atmosphere—45 to 55 degrees for lemons and 50 to 55 degrees for limes, both at 85 to 95 percent humidity. During this process, the rind thins and becomes more intense in color, and the flesh, which is hard and dry at harvest, becomes juicier. Both lemons and limes are very cold sensitive. If they are stored below 50 degrees for too long, the rind will become pitted and splotchy, and decay will accelerate. Fruit that is harvested at an early age is prone to what those in the trade call “oil spotting”—brown stains on the surface of the rind, caused when the oil cells rupture after the fruit has been bumped and bruised.
Although most people tend to think of squeezing a lemon or lime for the juice, good cooks know that the most flavorful part of the fruit is the peel, or, to be more specific, the surface of the peel. That part is appropriately known as the “zest,” where the fruit’s aromatic oil glands lie. The juice of a lemon or lime may have overtones of flavor, but it is obscured by the extreme acidity. With the zest, there is very little pucker to distract from the fruit’s wonderful aromatic qualities. For this reason botanists call this part of the peel the “flavedo.” Just underneath it is the “albedo,” the bitter part you don’t want to eat. The albedo is composed of white, pithy material—the main conduit for water and nutrition when the fruit is on the tree. Culinarily, the albedo is used almost exclusively as a source of pectin, which encourages jelling.
WHERE THEY’RE GROWN: Lemons are grown mostly in California, with some coming from Arizona and a few from Florida. Limes are almost entirely imported, with most coming from Mexico.
HOW TO CHOOSE: Choose fruits that are heaviest for their size and have the strongest perfume. With Meyer lemons, look for fruit with a baby-soft, thin peel. With West Indian (Key) limes, remember that the yellower they are, the riper.
HOW TO STORE: Lemons and limes should be stored at room temperature. Chilling will cause them to spoil more rapidly.
HOW TO PREPARE: If you want lemon or lime zest and don’t have a zester, use a sharp, thin-bladed paring knife to cut away just the colored part of the peel, leaving behind as much of the bitter pith as you can. Lay the peel cut side up on a cutting board, press the knife blade flat against it and slice away any traces of pith. Then you can cut the zest into thin strips.
ONE SIMPLE DISH: You can make a simple sauce for pasta by simmering heavy cream and lemon zest, then adding a little minced fresh parsley and maybe some pine nuts just before serving. Remember that the sauce should only lightly coat the pasta, not puddle in the bottom of the bowl.