Everybody knows that lemons symbolize freshness. Cooks know it. Detergent manufacturers certainly know it.
But there's another kind of lemon flavor without that sharp, clean pungency--a mellow sort of lemoniness, plush, perfumed and exotic, with perhaps a decadent suggestion of the boudoir about it. In English it goes by names like salted or pickled lemons. The Moroccans use a more poetic expression: lim mraqqed , "lemons that have been put to sleep."
Preserved lemons needn't be confined to North African stews; a little bit can add a whiff of mystery to many other dishes. Mince some into scrambled eggs or dishes made with ricotta or mild-flavored cheese. Throw a little into curry or lobster salad. Add some of the pickling juice to a vinaigrette. Don't overdo it, though--the aroma is so heavy that it can cloy.
People have been pickling lemons for hundreds of years. In the 13th-Century Arabic cookbook "The Link to the Beloved," we find this recipe:
"Take lemons and slice them crosswise and fill them with crushed salt. Then press them into a bowl and let them sit for two nights so that they soften. Then press everything strongly into a glass jar. Squeeze lemon juice and pour it over them to cover, and seal it with olive oil. Their flavor will keep well." (To us, the interesting thing about pickled lemons is the new flavor that develops, but in the Middle Ages people basically cared about the fact that the lemons didn't spoil.)
The phrase "slice them crosswise and fill them with crushed salt" refers to the technique, still used today, of cutting the lemons nearly into four pieces and sprinkling the exposed interior with salt. Paula Wolfert, author of "Couscous and Other Good Food From Morocco," reports that Moroccan pickling companies have also invented a way of salting lemons that does not involve slicing the fruit open. "These days," she says, "all the pickled lemons you see in a Moroccan market are whole."
By the way, if you don't use pickled lemons frequently and don't have room to keep a pickling jar in the refrigerator, the medieval idea of putting a layer of oil on top of the brine is a good one. It keeps the top lemons from being exposed to the air, which would cause them to turn mushy rather quickly.
In "A Book of Middle Eastern Food," Claudia Roden gives a slightly different recipe for pickling lemons. You slice them, salt the slices and leave them overnight on a slanting surface for the juices to drain away. Then, instead of putting the slices in water or lemon juice, you cover them with olive oil, and they're ready in about three weeks. Roden likes to sprinkle the slices with paprika before putting them in oil so that they develop an attractive salmon color.
Vinegar is sometimes used for the pickling liquid in India and Pakistan, and even in Morocco. Michel Ohayon of Koutoubia Moroccan Restaurant in Westwood prefers a pickling liquid of vinegar and water in equal proportions--or two parts vinegar to one part water "if you're in a hurry."
The juicy interior of a pickled lemon can be eaten, but it's beside the point. The magic is in the peel. In fact, Moroccans sometimes cut the zest from the peel and salt it dry. The slices of zest slowly curl up and brown and develop something of the same rich aroma.
This suggests that the removal of moisture from the peel, either by salting or physical drying, has something to do with the change. The same thing happens in the dried limes which Oman exports to other countries around the Persian Gulf (in Iran they're known as limu Omani ). The Omani limes are simply left out in the sun until they shrivel. Like the Moroccan dry-pickled peel, they have to be reconstituted in water or added to cooking liquid before they can be eaten.
In "Couscous and Other Good Food From Morocco," Paula Wolfert gives a quick recipe which calls for the usual quartered lemons to be frozen and thawed before salting and covering with liquid. Claudia Roden also reports that her lemon pickle ripens more quickly if the slices are frozen before they are salted. Here we have more drying of the flesh. When the lemon quarters or slices thaw, water oozes from them because ice crystals have punctured cell walls.
So what's going on here? We don't know yet. "I find virtually nothing in the scientific literature about what happens when lemons pickle," says science writer Harold McGee, author of "On Food and Cooking."
McGee tentatively concludes that the flavor changes have to do with aromatic compounds known as terpenes, which are found in lemon peel and also in pine sap, and he suspects that microbes are doing the work. "We know that bacteria and yeasts can metabolize terpenes," he says. "They can make them disappear or transform them into one another."
McGee has tried pickling Meyer lemons, with no success (see "Experiments Gone Sour, H9). "The fact that the Meyer doesn't give the same smell lends support to this hypothesis," he says, "because the difference in flavor between the Meyer and the Eureka lemon (the usual supermarket lemon, which is also the usual garden lemon in Southern California) is the difference between two sets of terpenes. The Meyer contains a relatively large quantity of thymol, a chemical related to terpenes that is a compoment of thyme oil, and I do think I can detect an herbal quality in the Meyer.
"The salt doesn't do it. As for the dried lemons, you can't rule out fermentation going on there either. As long as the temperature is around 100 to 110, even as high as 120 degrees, there'll be bugs living there. And if the limes are dried in direct sun, a lot of volatile compounds will evaporate as the flesh cracks and oil cells break down, there'll be a lot of chemical and physical alteration."
Since the scientific verdict is still out, though, we can go on thinking of pickled lemons as lemons that have been put to sleep.
PICKLED LEMON CHEESECAKE
A dessert showcasing the exotic perfume of pickled lemons. If you want, garnish with slices of pickled lemon.
1 pound ricotta
1 cup sugar
2 pickled lemons, or 3 pickled limes, seeded and diced
3 tablespoons flour
Combine ricotta, sugar and eggs in mixing bowl. Add diced lemons. Stir in flour and mix well. Set aside until ready to fill Pasta Frolla.
3/4 cup flour
3 tablespoons sugar
3 tablespoons butter, room temperature
Combine flour and sugar in mixing bowl. Cut butter into flour mixture until crumbly. Mix with egg.
Knead just until mixture can be formed into ball. Cover with plastic wrap. Let stand 30 minutes at room temperature.
Roll out pasta frolla and line 8-inch springform pan with dough. Pour in ricotta mixture. Bake at 375 degrees 40 minutes. Remove from oven. Let stand 30 minutes before slicing or removing from pan. When cool, refrigerate.
Makes 8 servings.
Each serving contains about:
457 calories; 166 mg sodium; 195 mg cholesterol; 19 grams fat; 60 grams carbohydrates; 15 grams protein; 0.05 gram fiber.
* Ironwork in pickled lemon cheesecake photo from Architectural Detail, South Pasadena.