Lemons and Limes as Lifesavers

A few centuries ago, scurvy--which we now know is caused by vitamin C deficiency--was both rampant and deadly.

Then sea captains, without really knowing why, began ordering limes to be carried on long ocean voyages to keep their sailors from getting sick. And during the 1849 California Gold Rush, miners were willing to pay as much as $1 a lemon to ward off illness.

But it wasn’t until 1932, with the actual discovery of vitamin C, that researchers understood what it was in lemons and limes, and other fruits and vegetables, that protected us against the disease.

Students of art and literature know that lemons and limes have been around since the 2nd or 3rd centuries, but it was Christopher Columbus who brought so many fruits and vegetables to the New World and who is responsible for introducing the seeds that could thrive in the tropical Caribbean climate. Today, in fact, Florida produces most of the limes grown in North America. California produces few limes, but nearly a third of the world’s commercial lemon crop.

Lemons are higher than limes in vitamin C; a medium lemon (3 1/2 ounces) has approximately 53 milligrams of vitamin C, which is more than 70% of the recommended daily intake for women (75 mg) and more than 58% for men (90 mg). The same-sized lime contains about 29 mg of vitamin C.

Since both are tart, they’re not fruits you’d be likely to snack on, and neither counts as a significant dietary source of vitamin C for most people. Nonetheless, they are superb catalysts for bringing out the flavors of foods. This can be especially important for people who watch their salt intake; the acidity of lemons and limes can stimulate the taste buds so much that salt is not needed.

Vitamin C, however, is not the only valuable nutrient in citrus fruits. According to recent research, they are full of potent plant chemicals with nearly unpronounceable names; many of these compounds are being looked at as ways to lower the risk of stroke, cancer and heart disease. But before you run out to buy expensive citrus extracts, remember: It may be the way this combination of riches is packaged in the fruits themselves that causes them to be so important. There is still no substitute for eating fruits and vegetables in combination with a healthy diet.

You’ll find basically two types of lemons: Eurekas or Lisbons. The only noticeable difference is in the shape of the fruit. Eurekas have a short neck, while Lisbons taper to a pointed nipple. Most of the lemons grown in Florida are a type of Lisbon fruit known as “Bearss” (and, yes, there is really a double “s”).

Most of the limes we see come from a strain that probably originated in Tahiti, although there are similar but distinct varieties: the Persian, from Florida, and Bearss, from California. Key limes, which are smaller and rounder, come only from southern Florida.

When you buy the fruit, look for those that are firm, glossy and brightly colored. Lemons should not be greenish, and limes should not be yellowish. Actually, limes turn from green to yellow as they ripen, but the immature, green fruits are the most flavorful. Not too long ago, we saw a hybrid of the two fruits that was green and yellow.

Extra-large lemons are likely to have very thick skins and little juice. Stay away from any that are shriveled and spongy or have coarse exteriors. Choose limes the same way. Lemons will keep for about two weeks at room temperature, but limes must be refrigerated immediately. Either will keep for up to six weeks if stored in a plastic bag in the refrigerator crisper.

If you find yourself with lots of lemons or limes, try squeezing the juice into ice-cube trays and then transferring the frozen cubes to a plastic bag to use whenever you need them.

There’s no shortage of gadgets on the market to get the juice out of citrus fruits, even though there is a perfectly easy way to do it without the toys: Make sure the fruit is at room temperature or warmer. You can heat it up by putting it in hot water for a few minutes or microwaving it for about 30 seconds. Then roll it around on the counter until it feels nice and soft. Cut the fruit in half across the middle, and squeeze it with your hand, using your fingers or a strainer to catch the seeds. If you need only a little juice, put a toothpick into the fruit, and squeeze around the opening. To reseal it, just replace the toothpick.

You’ll get 3 or 4 tablespoons of juice, and 2 or 3 teaspoons of zest from a large lemon. A large lime will give you 2 to 3 tablespoons of juice and 1 or 2 teaspoons of zest. The zest of the lemon or lime is the colored part of the peel. When you remove it, be sure to leave the white part behind, as it tends to be bitter.

Lemons and limes are essential ingredients for the creative cook because they freshen and flavor almost every food. The acid in the juice will even keep bananas, apples, peaches, avocados and other cut fruits from turning brown. Once you get accustomed to cooking with lemons or limes, you’ll always want to have some around, although bottled juice will certainly do in a pinch.

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Dr. Sheldon Margen is a professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. Send questions to Dale Ogar, School of Public Health, UC Berkeley, Berkeley, CA 94720-7360, or e-mail to daogar@uclink4.berkeley.edu.

Eating Smart appears the second and fourth Mondays of the month.