Beyond the Navel

by Emma Onawa


Pity the navel orange. Its ubiquitous presence has to stand in for the many orange varieties nature has to offer. While the navel is a fine orange,1 it’s hardly a stand-in for its juicier, sweeter relatives. As with many other fruits and vegetables, corporate agricultural practice has promoted the navel orange at the expense of a multitude of other varieties. It’s sort of the “Delicious” apple of the citrus kingdom.

Origins and physiology

Citrus is the common term for the genus Citrus, a flowering shrub or small tree in the rue family (Rutaceae). The term citrus originates from the Latin, referring to the plant known as the citron, which in turn derives from the Greek word for cedar (kédros).

As a group, citrus plants also are known by the Romance word argumes, which means “sour fruits.” Citrus plants have evergreen leaves that drop only when stressed. Its fruit is a specialized juice-laden berry known as hesperidium, and has a leathery peel or rind known as a pericarp. Citrus fruits get their fragrance partly from flavenoids and liminoids.

The most common members of the citrus family include oranges, lemons, limes, and grapefruit. In tropical regions with no winter, citrus fruits remain green to maturity. More colorful fruits develop in regions with a cool (diurnal) winter.

The terms "mature" and "ripe" often are thought to be synonymous, but they have different meanings. Fruits are mature when their growth phase is completed, after which ripening occurs, which entails starch converting to sugar, decreased acids, and a softening and change in the fruit’s color. Unlike many other fruits, citrus does not ripen after being picked.

Citrus plants originated in southeast Asia and were first introduced to the United States by early Spanish explorers at St. Augustine, Florida, in 1565. From there they spread slowly across the country, reaching California in 1769.

A 2007 United Nations study found that China, Brazil, the U.S., Mexico, India, and Spain produce most of the world’s citrus. Brazil produces the most oranges, China the most mandarins, India the most lemons and limes, and the U.S. the most grapefruit. Within the U.S., California produces the most fresh oranges, while Florida produces the most juice.

Nutritional benefits

Of course, citrus is a wonderful source of vitamin C. One cup of orange juice provides about 125 mg of vitamin C, while a medium orange or grapefruit yields 70 mg and 56 mg, respectively. But citrus also is a great source of other nutrients, including vitamin A, some B vitamins, folate, potassium, and several types of phytochemicals, and other nutrients.

Research also indicates that citrus can aid in the prevention of cardiovascular disease, neural tube defects, anemia, and cataracts. It’s also believed that citrus improves bone health and cognitive function, and helps to dissolve kidney stones and prevent asthma. Citrus is also a great source of fiber.

Organic versus non-organic

While many studies have demonstrated that organic produce has better taste, plant metabolites, and nutrients, some studies are inconclusive. Moreover, non-organic citrus fruits typically do not appear on the “Dirty Dozen” lists of fruits and vegetables. Arguably, a more important determinant of nutrient value and taste would be the individual variety and conditions under which specific crops are grown, picked, and processed.

A 2005 Italian study on two cultivars of oranges grown under organic and conventional methods indicated that organic oranges were 12% higher in vitamin C, while the two conventional fruits had 30% and 12% more nitrogen than the organic samples. Lower levels of nitrogen are thought to reduce the formation of certain cancer-causing enzymes, known as nitrosamines, in the gut.

An equally important consideration is the processing that most citrus undergoes. Both conventional and organic are waxed to prevent moisture loss and make the fruit more attractive. The wax applied to conventional fruit typically is petroleum-based and often contains fungicides or preservatives. Wax used on organic fruit typically is derived from non-petroleum sources, such as beeswax, combined with vegetable-based oils.

Conventional growers are also known to dye their fruit to improve color, a practice prohibited for organic growers. Ethylene gas, used to “degreen” fruit, is allowed for both conventional and organic growers, but organic growers are less inclined to use it. Although some research is inconclusive at this point and practices are mixed, organic is still the better way to go for these and a host of
additional reasons well-known to those who care deeply about the environment and the food we eat.


Varieties of Citrus

Although all citrus fruits are acidic, they can be divided generally into sweet (oranges and grapefruit) and acid types (kumquats, lemons, and limes).

Oranges

Sweet oranges are the most popular of citrus fruits and they serve well. Americans consume far more oranges as juice than fresh. Of the fresh variety, Valencias (which are actually grown primarily for juice) and navels are the most commonly available. Nonetheless, there are many other delicious types available in co-ops, health food stores, and, increasingly, in conventional grocery stores.

Mandarins are a small orange with a loose skin. The popular Clementine is a seedless mandarin, and the Satsuma is a seedless variety from Japan. Tangerines are an orange-red mandarin with a distinct citrus taste. The Minneola is a cross between a tangerine and a grapefruit and features the little nose at the growing tip.

Tangelos are a cross between a tangerine, grapefruit, and orange. Uglis, aptly named for their bumpy greenish yellow skins, are a variety of tangelo. The Temple orange is a "tangor," a cross between the sweet orange and a mandarin. It’s easily peeled, fragile, juicy, and has a short season and shelf life.

Blood oranges are a deep red with an intensely sweet orange flavor. The red-fleshed Cara Cara navels have been immensely popular at Hampden Park Co-op in recent years. The kumquat is part of the orange family, much smaller, with a sweet/sour taste and edible skin.

Grapefruit

The grapefruit is believed to be a cross between the orange and pomelo. Pomelos (also pummelo, shaddock, or jabong) look like a large grapefruit, but their bulk consists of a foam-like pith that’s valued for candying. It is pale green to yellow when ripe, and has a sweeter, milder taste than grapefruit. Pomelos can be peeled into segments and added to salads.

Sweeties are a variety that’s a cross between the pomelo and grapefruit. They look like a green grapefruit and are sweeter.

Grapefruit comes in white and red/pink types. Contrary to popular belief, pink or red grapefruit is not necessarily sweeter than white—more important are the variety of fruit and the conditions under which they’re grown.

Lemons and limes

Lemons and limes are acidic varieties of citrus. Lemons are thought to originate in India or Myanmar. In the U.S., most are grown in California and Arizona. The Eureka variety is ubiquitous in grocery stores. The Meyer lemon—a favorite of chefs—is becoming better known. Meyer lemons are seedless and smaller, rounder, and less hardy than Eurekas. Their juice is much sweeter and thinner. They are a cross between a lemon and an orange (probably mandarin).

The lime has the most detoxifying ability of all citrus fruits. It’s believed to have originated in Malaysia. The Persian or Tahitian is the variety commonly found in grocery stores. It’s generally seedless. Key limes are smaller than Persians and are yellow when ripe. They also have more seeds, thinner skin, stronger aroma, and are more tart and acidic. They are named for their association with the Florida Keys, where they’re used to make Key Lime Pie. Like Meyer lemons, they can be hard to find.

Recipes

Lemon-Tofu Cheesecake

Crust

2 cups graham cracker crumbs
¼ cup maple syrup
½ teaspoon almond extract

Filling

1 pound silken tofu
1/3 cup sugar
1 tablespoon tahini
½ teaspoon salt
2 tablespoons lemon juice
1 teaspoon lemon zest
½ teaspoon almond extract
2 tablespoons cornstarch
2 tablespoons soymilk
(rice milk will also work)

Topping

¼ cup slivered almonds (optional)

Preheat the oven to 350° F. In a medium bowl, combine graham cracker crumbs, maple syrup and almond extract. Mix until the crumbs are moistened.

Prepare a 9–inch springform pan by spraying the bottom and sides with nonstick oil spray, or by oiling using a paper towel. Tip crumb mixture into the springform pan and press it evenly on the bottom. Bake the crust for 5 minutes, then remove it from the oven and set it aside to cool while you prepare the filling.

Blend all the filling ingredients in a food processor or blender for about 30 seconds, or until smooth. Pour filling into the springform pan over the cooled crust.

Bake for about 30 minutes or until the top of the cheesecake is lightly browned. Remove the cheesecake from the oven and allow it to cool.

Place the cooled cheesecake in the refrigerator for at least 2 hours until it is thoroughly chilled and firm. To serve, take a long knife and heat the blade in hot water. Slide the blade of the knife
along the edge of the cooled cheesecake to ensure that it will separate from the pan. Release the springform ring, slice, sprinkle with slivered almonds if desired, and serve cold.

(Source: <www.food.com/recipe/i-dont-believe-its-lemon-tofu-cheesecake-59515>)

Orange and Olive Salad

6–8 oranges
20 kalamata olives, stoned
1 tablespoon lemon juice (or at least half a lemon's worth)
1 pinch ground cumin, to taste
1 pinch chili powder, to taste
1 teaspoon superfine sugar
1 pinch salt

Remove the peel and pith from the oranges, then divide into segments (reserving any juice), leaving them whole or chopped as preferred.

In a bowl, mix the olives with the orange segments and juice. Add remaining ingredients. Serve chilled.

(Source: <low-cholesterol.food. com/recipe/orange-and-olive-salad-138114>)



Notes

1. Navels are popular with growers because they have a long growing season. The navel orange was
first produced as a mutation found on a Selecta orange tree at a monastery in Brazil. There are now more than 50 varieties. The most common is the Washington navel, which is a parent to most of the navels now produced. Only one surviving original parent tree still produces fruit in California.

2. The word cedar is believed to originate from the practice of Hellenistic Jews’ use of citron fruits in place of a cedar cone during the Feast of the Tabernacles (Sukkot) or possibly from the similarities between the smell of citrus leaves and fruits and that of cedar.

3. With oranges, color is not necessarily an indicator of ripeness. Sometimes the rind will turn orange before the fruits are ready to eat.

4. Pythochemicals are thought to be antioxidant, energize enzymes that fight cancer, aid in digestion, and block the absorption of nitrates. They are found only in plant-based foods. Citrus fruits also contain calcium, thiamin, niacin, vitamin B6, phosphorus, magnesium, copper, and riboflavin.

5. “Nitrogen Metabolism Components as a Tool to Discriminate between Organic and Conventional Citrus Fruits,” Paolo Rapisarda and others, Journal of Agricultural and Food Chemistry, Vol. 53, No. 7, April 6, 2005.

6. The Clementine was born when clergyman Pierre Clement crossed a mandarin with an orange, which eliminated the seeds and created a looser skin.

Sources and Resources:

1. Food and Agriculture Organization of the United Nations: “Nutritional and health benefits of citrus fruits,” <www.fao.org/docrep/x2650T/x2650t03.htm >.

2. The Free Dictionary: “Key Lime,” <encyclopedia.thefreedictionary. com/Key+Limes\>.

3. The Free Dictionary: “Valencia orange,” <encyclopedia.thefree dictionary.com/Valencia+orange>.

4. The Fruit Pages: “Citrus Fruits,” <www.thefruitpages.com/citrus.shtml>.

5. The New York Times: “Temple Oranges, Here Today…,” <diners journal.blogs.nytimes.com/2012/01/20/temple-oranges-here-today/>.

6. The Nibble: “Organic Versus Conventional Citrus,” <www.the nibble.com/reviews/nutri/matter/2008-02-organic-citrus2.asp>.

7. OMG Facts: “All navel oranges are clones,” <www.omg-facts.com /Science/All-Navel-Oranges-Are-Clones/52017>.

8. Organic.org: “About Citrus,” <www.organic.org/articles/showarticle/article-164>.

9. Specialty Produce: “Navel
Oranges,” <
www.specialty produce.com/index.php?item= 8521&name= Navel_Oranges>.

10. The University of Georgia: “Citrus Fruit for Southern and Coastal Georgia,” <www.caes.uga. edu/publications/pubDetail.cfm? pk_id=7787>.

11. Wikipedia: “Citrus,” <en.wikipedia.org/wiki/Citrus>.

[Emma Onawa has been a veteran co-op owner and shopper for 30 years and has never met a cheese or cat she doesn’t like.]