Grapefruit Ethnobotany: The Generous Versatility of Grapefruit Trees (Citus x paradisi) as Food Sources and So Much More

The word grapefruit (Citrus x paradisi) calls to mind the subtle grape like flavor that is exuded by the fruit. It also captures the essential grape like clustering of the fruits as they grow on the tree's branches. But otherwise, the name conveys an inaccurate impression of the distinctions between the grapefruit tree and the grape vine.

Externals: What grapefruit looks like

Grapefruit tree bark, branches and trunk: The grapefruit tree has an attractively reddish brown bark whose surface is marked by long ridges. It may reach a mature height of 15 to 20 feet (4.5 to 6 meters) in home gardens. In commercial orchards, it tends to reach a mature height of 22 to 30 feet (7 to 10 meters). But because a tree never stops growing, grapefruit trees that are allowed to age in the landscape may reach ripe, old heights of 45-50 feet (13.7 to 15.24 meters).

In terms of form, the tree has a slender trunk and branches in youth. For example, a young tree may have a trunk that is around 6 inches (15 centimeters) in width. It tends to keep its basic, graceful form without the need for pruning by its cultivator. But the oldest grapefruit trees may have trunks 8 to 10 feet (2.4 to 3.048 meters) wide. They also may require some removal of dead or dying branches, which always should be done in spring.

In terms of shape, the grapefruit tree has a rounded top of spreading branches. The twigs on the branches grow short, supple thorns. This is in line with Citrus genus members tending to have spiny shoots. It also is a characteristic that is more pronounced in grapefruit trees grown from seed and less so in those grown from budded rootstock.

Grapefruit tree leaves: The grapefruit is a subtropical, evergreen tree whose leaves tend to stay on their branches two years before dropping. Grapefruit leaves always are dark green on the upper surfaces and lighter beneath. Their margins are broken by many extremely minute, rounded teeth.

Grapefruit leaves may grow to a mature length of 3 to 6 inches (7.5 to 15 centimeters) and width of 1-3/4 to 3 inches (4.5 to 7.5 centimeters).

Leaves are dotted with pellucid (Latin: per, "through" + lucere, "shine") glands, which are tiny glands full of the oil that is responsible for the plant’s distinctive leafy aroma.

The grapefruit tree's leaves are attached to petioles (Latin: petiolus, "little foot"), which are the stretch of stalk at one end of which is the leaf and at the other end is the plant stem. The petioles have wings, which are a fleshy protective layer. Grapefruit wings are either obovate, in which they are attached to the narrow end of a gently oval, egg-shaped leaf, or oblanceolate, in which they are attached to the narrow end of a tapering leaf that is bluntly broadest around the middle.

Grapefruit flower: The spring-blooming grapefruit flower may be born singly or in clusters. It is a bright, clean, clear white.

Flowers may range in size from 1-3/4 to 2 inches (4.5 to 5 centimeters) across.

The grapefruit tree's flowers have four petals, which are unexpected in terms of the generally five-petalled citrus flower. But as the photo indicates, every once in a while the grapefruit tree remembers its citrus heritage and actually produces a quirky flower with five petals.

The grapefruit flower is described as complete. This means that it contains all of the parts necessary in order to self-fertilize by cross-pollination. Nevertheless, bees are attracted to the flower's generally ample supply of pollen and therefore help in the grapefruit pollination process.

Grapefruit tree fruit: The fruit of the grapefruit tree grows in clusters that some find reminiscent of grapes. Generally, the fruits form into groups of 10 to 20 on a branch. Each fruit is generally round. It measures 4 to 6 inches (10 to 15 centimeters) in width. It may weigh 1 to 5 pounds (0.45 to 2.27 kilograms).

The pericarp or peel offers a smooth surface over which many fine dots can be seen. It can be as much as 3/8 inch (1 centimeter) thick. It generally is pale lemon in color although it sometimes is blushed with pink. The outer surface, which contains essential oils and is called skin, rind, flavedo or epicarp, is aromatic. The spongy, thick, white inner surface is called the albedo or mesocarp.

The actual fruit may be solid or have a semi-hollow center. The pulp may be whitish, pale yellow, pink or deep red, the latter color of which is due to the presence of the pigments beta-carotene and lycopene. It is divided into 11 to 14 segments with thin membranous, somewhat bitter-tasting walls that are known as the endocarp. Its juicy flavor, which comes from potassium salt, ranges from somewhat to sweetly acid when fully ripe.

Grapefruit tree seeds: It is possible for each individual grapefruit to have few or many seeds. Grapefruits are considered seedless if each one has a range of 0-6 seeds within the pulp. Seedlessness points to the presence of little viable pollen and few or no fertile ovules. In contrast, the presence of viable pollen and fertile ovules may result in the production of as many as 90 seeds within one grapefruit. Either way, the seeds are white in color, elliptically pointed in shape and about one-half inch (1.25 centimeters) in length. Unlike its suspected parent pomelo, the grapefruit produces seeds from each of which two seedlings sprout.

That can be a lot of seeds when one considers the average fruit-bearing capabilities of grapefruit trees. Generally, a grapefruit tree can be counted on to produce at its lowest range of productivity at least 25 pounds (11.33 kilograms) worth of fruit in the home orchard and 275 pounds (125 kilograms) in the commercial orchard each year. At its uppermost productivity range, one grapefruit tree may yield as much as 250 pounds (113.39 kilograms) worth of fruit in the home orchard and 1,500 pounds (680 kilograms) in the commercial orchard each year.

Grapefruit tree uses: Creative inspiration

The grapefruit is as culturally current as it is environmentally conscious and gastronomically appealing in its uses. For example, Grapefruit is the name of a psychedelic pop/rock band that was based in London, England during the 1960s. The group was formed in 1967 after band guitarist and lead vocalist John Perry (born July 16, 1949) met with Terry Doran, key figure within The Beatles’ Apple Publishing Ltd. and long-time acquaintance of musical genius John Lennon, MBE (October 9, 1940-December 8, 1980). John hoped to convey to the public the band’s innovative musical hybridization, in the same way that his wife, visionary artist, filmmaker, musician and writer Yoko Ono (born February 18, 1933), sought to break creative and spiritual barriers with her conceptual art book, Grapefruit, in 1964.

Grapefruit tree's versatile ethnobotany: The grapefruit tree’s inspirational role is as practical as it is creative. For example, every bit of the tree can be recycled. Grapefruit seed extracted oil is usable as a quick, odor-free household control of mildew and mold. Seed hulls then are effective in conditioning soil or, in combination with dried grapefruit pulp, for feeding cattle, which also may be fed molasses made from grapefruit packing plant waste. An essence extracted from grapefruit flowers treats insomnia and stomach aches. Extractions from leaves act as a natural antibiotic in bolstering the immune system. The wood from branches, trunks and whole trees serves as firewood or is constructible as household fixtures. Specifically, household furnishings made from grapefruit tree wood will be attractively fine-grained and yellow-colored as well as long-lasting in their plucky durability.

Creativity and practicality spill over into the grapefruit’s best known and most widespread use, as food for people who care about healthy lifestyles. Specifically, Dr. Suresh K. Balani of Millennium Pharmaceuticals, Inc. of Cambridge, Massachusetts observes:

"GRJ [grapefruit juice] is known to have antioxidant, antiseptic, cardiotonic, anti-inflammatory, anti-carcinogenic, antimutagenic, and hypocholesterlemic activities." (p. 460)

For example, consuming the pulp discourages urinary disorders. At the same time, it encourages overall health through its high vitamin C content and through the hostility of its flavonone naringin to cholesterol. It is seen in helping out in weight control through the slow release of carbohydrates into the blood stream and the concomitantly more controlled impact on blood sugar levels. As part of a healthy, high protein diet, it may lead to the loss of 10 pounds (4.5 kilograms) in 10 days.

Forbidden drug interactions or health conditions: Ironically, this forbidden fruit from the Caribbean has been forbidden to its devotees who are prone to kidney stones, take certain medicines or undergo hormone therapy. Specifically, Dr. Suresh Balani elaborates that "GRJ is a milieu of chemicals, including flavonoids, fruity esters, psoralen derivatives, sugars, polysaccharides, organic acids, vitamins, and minerals" (p. 445) and therefore "inhibits multiple enzymes" (p. 444) such as CYP3A4/5in the small intestine and PgP (phosphoglycolate phosphatase) in red blood cells as well as transporters such as OATP (organic anion-transporting polypeptide). Additionally, Professor R. Elaine Turner and Researcher Gail C. Rampersaud pinpoint the problematic interaction between grapefruit juice and drugs for high blood pressure or cholesterol; immunosuppression after transplant surgery; or treatment of anxiety, depression or insomnia as well as antihistamine drugs and protease inhibitors. It indeed is precisely for these reasons that, in terms of packaging and prescriptions, the United States Food and Drug Administration requires precautions or warnings for all drugs whose use is affected by interaction with grapefruit juice.

But grapefruit resilience yet may triumph. For example, Dr. Balani refers to the dissipation of grapefruit juice inhibitory effects within 72 hours after consumption of an 8 fluid ounce (240 milliliter) glass. Additionally, research findings reported by Paul Watkins, M.D., of the University of North Carolina in the May 2006 issue of the American Journal of Clinical Nutrition suggest that the furanocoumarins, or plant toxins, bergamottin and 6',7'-dihydroxybergamottin can be removed from the forbidden fruit juice, which thereby becomes sweeter tasting and monstrously orange juice-like in its non-interference.

Culinary panache: The recipes which are included in the next section show that the versatile grapefruit may be incorporated into any consumer’s favorite beverage or food item at any meal or snack time throughout the day. After four centuries of human interaction, therefore, the grapefruit still may be seen as forbidden fruit that is Eden-like in its irresistible appeal to any palate.

NECESSARY UTENSILS: Juicer or blender

INGREDIENTS:

blackberries: 8 ounces (250 grams) (NOTE: Thaw first if frozen)

pears: 3 ripe (NOTE: Remove stem and any seeds)

grapefruits: 2 peeled (NOTE: Remove any seeds)

DIRECTIONS:

Process ingredients in juicer. (NOTE: I sometimes process in my blender at liquefy setting.)

Serve immediately or store in refrigerator if prefer chilled.

SERVINGS: approximately 3 cups

NECESSARY UTENSILS: small muslin drawstring bag, large pot, about 8 half-pint sterilized jars

INGREDIENTS:

grapefruits: 4 large (about 26.45 ounces or 750 grams)

lemons: 2 medium

water: 8.5 cups or 2 litres

sugar: 6 cups

DIRECTIONS:

Thinly peel grapefruits and lemons into very fine strips. (NOTE: Crisscrossing a zester over the peels produces long or small fine strips.)

Removing pith and seeds, cut flesh into small pieces.

Place pith and seeds on a piece of muslin and tie shut.

Pour water into a large pot and add fruit, peel, and bag of pith and seeds. Cover and allow to sit overnight.

Next day:

Place pot on burner and bring to boil. Reduce to simmer and continue until peels are tender and water is reduced by half.

Remove bag.

Adding sugar, stir until dissolved. Then increase heat and boil rapidly until reaching the setting point (218 °F to 220°F [103.33 °C to 104.4 °C] on candy thermometer).

Allow to sit for 10 minutes. Skimming gently, pour into warm sterilized jars and seal.

INGREDIENTS:

kale: 1 bunch

olive oil: 1 tablespoon

celtic sea salt: ⅛ teaspoon

lime: 1

balsamic vinegar: 1 teaspoon

grapefruit: 1, sliced and chopped

DIRECTIONS:

Chop the kale into thin ribbons.

Drizzle the olive oil onto the kale. Then massage the kale with your hands.

Sprinkle with salt. Then add lime juice and vinegar.

Add grapefruit to kale. Toss salad.

Allow to sit for 15 minutes so that kale softens and flavors integrate.

Ready to serve.

INGREDIENTS: SAUCE

raw honey: 2 to 3 Tablespoons

lemon juice: 2 teaspoons

ginger, fresh and minced: 1/2 teaspoon

INGREDIENTS: SALAD

grapefruits: 2, peeled, seeded, diced

banana: 1, sliced

coconut, flaked or shredded: 1/2 cup

poppy seeds: 1 teaspoon (NOTE: Omit poppy seeds, if desired.)

DIRECTIONS:

Combine sauce ingredients (honey, lemon juice, ginger) in a small bowl and stir to blend.

Distribute salad ingredients (grapefruits, banana, coconut) in a medium bowl. Sprinkle poppy seeds.

Slowly add sauce, gently stirring as added.

Allow salad to sit for 10 to 30 minutes for marination.

When ready, serve with slotted spoon. (NOTE: Any remaining sauce may be reserved for other uses, such as adding into a smoothie.)

Makes 10x4 or 9x5 loaf or two 6-inch round cakes

SPECIAL UTENSILS/SUPPLIES: parchment paper (or nonstick paper), stand mixer with whisk attachment, long skewer, syrup brush

INGREDIENTS: CAKE

flour, all-purpose: 2 cups

baking powder: 1 3/4 teaspoon

kosher salt: 1 teaspoon

sugar, granulated: 1 2/3 cups

eggs: 2 large

milk, whole: 1 cup

oil, canola: 3/4 cup (NOTE: I substitue safflower oil)

pink grapefruit zest: 1 Tablespoon

vanilla paste OR pure vanilla extract: 1 teaspoon

INGREDIENTS: GRAPEFRUIT SYRUP

pink grapefruit juice (strained, fresh): 1 cup

sugar, granulated: 2/3 cup

INGREDIENTS: GRAPEFRUIT ICING

powdered sugar: 3/4 cup

pink grapefruit juice (fresh): 1 Tablespoon + 1 teaspoon

DIRECTIONS:

1. Preheat oven to 350 °F. Line pan with parchment paper or apply nonstick spray.

2. After sifting together flour and baking powder, stir in salt. Set aside.

3. Insert whisk attachment into stand mixer and add sugar and eggs to bowl. Beat for about 3 minutes at medium speed.

4. Add milk, oil, grapefruit zest, and vanilla bowl and beat.

5. Reduce speed to low and add flour-baking powder-salt mixture to beating bowl.

6. Spread batter in pan. After spraying or lightly oiling a paring knife, run the knife, about 1/2 inch deep, lengthwise down the center. This forms an even crack down the center in the top of the baked cake.

7. Bake for 30 minutes. Then rotate pan in oven for even coloring to cake. Bake for another 30 minutes or until a toothpick tests with only a few moist crumbs on it.

***Make syrup while the cake is baking:

8. In a small saucepan, combine grapefruit juice and sugar.

Bringing to a simmer, stir to dissolve the sugar. Simmer for 1 minute. Then set aside.

***Back to cake, which has finished baking:

9. Transfer baked cake to rack for cooling.

With a long skewer, poke deep holes every 3/4 inch across top of cake. Then brush syrup over cake. Use all of syrup. (NOTE: It may be necessary to allow syrup to soak into cake; be patient.)

Allow cake to cool for about 10 minutes.

10. Unmold cake and allow to cool to room temperature on rack.

***Icing:

11. In a bowl, combine icing ingredients (powdered sugar, grapefruit juice) and stir until smooth. Enjoy the light pink tint.

12. While drizzling the icing over the top with a spoon, allow to drip generously down the sides.

This hub is dedicated to the memory of my paternal grandfather, August, who added owning a grapefruit orchard in Dunedin, Florida, to his impressive list of accomplishments. Although he predeceased my birth, I know of his admirable qualities through his son, my father, and I remember grandfather August and his poetic reverence for life every time I am in the presence of grapefruits.

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My special thanks to talented photographers/concerned organizations who make their fine images, information, and recipes available on the internet.

My special thanks to Anton Health and Nutrition, Breville Food Thinkers, Elana's Pantry, and Shadowfoot for their delicious, nutritious recipes.

Also, my extra special thanks to abakedcreation.com for their clear, beautiful images of each important step in the Grapefruit Birthday Cake recipe, made available on Flickr as well as on their step-by-step presentation of the recipe on their blog, A Baked Creation.

Ackart, Robert. Fruits in Cooking. New York: Macmillan Publishing Co., Inc., 1973.

Better Homes and Gardens. So Good with Fruit. Meredith Publishing Company, 1967.

Chandonnet, Ann. The Complete Fruit Cookbook. San Francisco: 101 Productions, 1972.

Citrus. Edison, New Jersey: Chartwell Books, Inc., 1992, 1997.

Dixon, Pamela. New Ways with Fresh Fruit & Vegetables. London and Boston: Faber and Faber Limited, 1973, 1981.

Hodgson, Moira. Cooking with Fruits and Nuts. Indianapolis and New York: The Bobbs-Merrill Company, Inc., 1973.

Plagemann, Catherine. Fine Preserving. New York: Simon and Schuster, 1967.

Raddin, Charles S. "Grape Fruit." Pages 86-87. IN: William Kerr Higley, ed. Birds and Nature in Natural Colors: A Monthly Serial, Forty Illustrations by Color Photography, A Guide in the Study of Nature. Volume XV. January to May 1904. Chicago: A.W. Mumford, 1904.

Rubin, Cynthia & Jerome. The New Fruit Cookbook. Chicago: Henry Regnery Company, 1974, 1977.

Sinclair, Walton B. The Grapefruit: Its Composition, Physiology, and Products. Riverside: University of California, Division of Agricultural Sciences, 1972.

Small, Ernest. Top 100 Food Plants. Ottawa: National Research Council of Canada, 2009.

The Editors of Time-Life Books. Fruits. 1983.

Turner, R. Elaine and Gail C. Rampersaud. “Using Medications Safely: Interactions Between Grapefruit Juice and Prescription Drugs.” Gainesville: University of Florida IFAS Extension Publication #FSHN02-5, 2009. http://edis.ifas.ufl.edu/fs088

Waters, Alice and the Cooks of Chez Panisse in collaboration with Alan Tangren and Fritz Streiff. Chez Panisse Fruit. HarperCollins Publishers Inc., 2002.

Copyright Monday, October 17, 2011 by Derdriu