- Malus domestica
- Fall (October - March in warmer climates)
- Procyanidins, Quercetin, Luteolin, Kaempferol, Fisetin
Natural Antiangiogenic Molecules:
The apple tree is one of the most widely cultivated fruit trees in the world and is the most popular fruit in the U.S., U.K., Germany, and France. Its fruit is a member of the rose family Rosaceae. The Latin word for the fruit of such flowering plants is pome (hence the French term for apple, “pomme”), though this term most directly means “fruit” not “apple” and also refers to the fruit of other pome plants like the pear. The word "apple" comes from the Old English word "aeppel."
The apple has been known since pre-historic times, originating in Central Asia (Kazakhstan) and spreading from the Mediterranean to Europe through the ancient Greeks and Romans. (Claudius Appius, a wealthy Roman politician, may have first introduced the apple to Rome from the Greek Peloponnesia.) Despite its Asian and European origins, the apple is strongly associated with American history. However, only the crab apple is native to North Ameria. But apples were among the first fruits planted by colonists in America, in Massachusetts, and then spread westward by American frontiersman John Chapman (also known as Johnny Appleseed).
Most of the aroma of apples originates from the apple’s outer skin where aromatic esters (ethyl acetate) are formed by enzymes concentrated in the skin. The characteristic smell of cooked apple pulp comes from the floral-smelling carotenoid pigment (damascenone).
A high concentration of pectin (a polysaccharide in plant cell walls) in the skin and seeds of apples, make the fruit an ideal gelling agent for jams and jellies.
The apple grows well in temperate climates around the globe, with production in China as great as in the U.S. Thanks to widespread production, seasonal differences between hemispheres, and effective cold storage, apples are available year-round. There are over 15,000 varieties of apple. The American Delicious variety comprises half of all commercial apples produced. Other well-known varieties include Golden Delicious (first raised in West Virginia, and which grow best in warm countries; France being its largest exporter) and Granny Smith (named after one Ann Smith, an Australian who first discovered the variety growing in her 19th century backyard). McIntosh apples originated from Canada, Fuji and Crispin apples in Japan. The Gala apple is a cross between Golden Delicious and Kidd’s Orange Red and first grown in New Zealand. European varieties that are ancient are considered "heirloom" and some are connoisseur fruit varities, such as the Reine des Reinettes and Caville Blanc d'Hiver from France; and Cox's Orange Pippin and Egremont Russet from Britain.
Different varieties of apples are produced for different uses. There are eating or dessert apples (usually firm, crisp, juicy, and sweet), cooking apples (those that maintain their shape and do not disintegrate under heat), and cider apples (Malus sylvestris),. Cooking apples tend to be tart when raw and well-balanced when cooked. Some familiar varieties, like the Granny Smith and Golden Delicious, are considered “dual-purpose”, good for cooking when young and tart, but better for eating when older and ripe.
Apples contain a natural "wax" (ursolic acid) on their surface that serves as a water repellent barrier. In fact, rubbing a freshly picked apple on the palm may result in a fine white powder that is the natural wax. However, during commerical processing, the natural wax is removed during washing so is replaced by carnauba (palm plant) wax or shellac (tree bark resin secreted by the lac bug). Although peeling removes the artificial wax, it also eliminates the apple peel, which contains many healthful bioactive molecules.
Apples are climacteric fruit, which means they continue to ripen even after being picked. (in contrast, non-climacteric fruit, like melons and most berries, do not get sweeter after harvest; therefore, those fruits should be picked at the peak of their ripeness and require more careful selection by consumers). Many commercial apples are now also stored at reduced oxygen and elevated carbon dioxide to slow down the ripening process, allowing storage for 9-12 months.
During post-harvest ripening, the natural (effects from other ripening fruits; e.g. mutually-ripening fruit in a closed paper bag) or synthetic application of ethylene gas prompts climacteric fruit to further ripen, themselves producing ethylene. They begin to consume oxygen and release carbon dioxide, or “respire”. Ethylene gas triggers the enzyme amylase to convert starch to sugar in this process, which accounts for an increased sweetness.
Apples are normally sold ripe and should be cold-stored; they can be wrapped firmly and stored stem-down in the refrigerator to avoid moisture loss.
Scientific and epidemiological studies have provided accumulating evidence that apples have cancer-preventive properties. In the Nurses Health Study involving 77,000 women, a significantly lower risk for lung cancer was observed among women for increases of 1 serving per day of apples or pears. Similar results were obtained from a Finnish cohort study involving 10,000 men and women. The results of a case-control study conducted in Hawaii with 528 lung cancer cases and 528 controls found a statistically significant decrease in lung cancer risk with increased consumption of apples and onions, which are rich sources of the flavonoid quercetin. An analysis of case-control studies conducted in Italy found that people who consumed at least one apple per day had a significantly reduced risk of colorectal cancer and cancers of the oral cavity, larynx, breast and ovary relative to those who ate less than an apple a day.
Apples and apple juice are rich in bioactive compounds called polyphenols, which can be further subdivided into flavonoids,. Flavonoids in turn, can be further subdivided into several classes of compounds (flavonols, procyanidins) and single molecules (quercetin, catechins) that have anti-cancer and antiangiogenic properties. In a recent study published in the journal Molecular Nutrition & Food Research, German scientists examined the specific chemopreventive properties of a polyphenol extract of apple juice. Among their findings, numerous compounds in apple juice have anti-inflammatory effects. Apple procyanidins were found to inhibit Cox-1, a key enzyme involved in chronic inflammation and angiogenesis.