About Apple

The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family (Rosaceae). It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring and produce fruit in the fall. The tree originated in Western Asia, where its wild ancestor, Malus sieversii, is still found today. Apples have been grown for thousands of years in Asia and Europe, and were brought to North American by European colonists. Apples have been present in the mythology and religions of many cultures, including Norse, Greek and Christian traditions. In 2010, the fruit's genome was decoded, leading to new understandings of disease control and selective breeding in apple production.
There are more than 7,500 known cultivars of apples, resulting in a range of desired characteristics. Different cultivars are bred for various tastes and uses, including in cooking, fresh eating and cider production. Domestic apples are generally propagated by grafting, although wild apples grow readily from seed. Trees are prone to a number of fungal, bacterial and pest problems, which can be controlled by a number of organic and non-organic means.
At least 55 million tonnes of apples were grown worldwide in 2005, with a value of about $10 billion. China produced about 35% of this total. The United States is the second-leading producer, with more than 7.5% of world production. Iran is third, followed by Turkey, Russia, Italy and India. Apples are often eaten raw, but can also be found in many foods (especially desserts) and drinks. Many beneficial health effects have been found from eating apples; however, the seeds are slightly poisonous and two forms of allergies are seen to various proteins found in the fruit.

Health benefits
The proverb "An apple a day keeps the doctor away.", addressing the health effects of the fruit, dates from 19th century Wales. Research suggests that apples may reduce the risk of colon cancer, prostate cancer and lung cancer. Compared to many other fruits and vegetables, apples contain relatively low amounts of vitamin C, but are a rich source of other antioxidant compounds. The fiber content, while less than in most other fruits, helps regulate bowel movements and may thus reduce the risk of colon cancer. They may also help with heart disease, weight loss, and controlling cholesterol. The fiber contained in apples reduces cholesterol by preventing reabsorption, and (like most fruits and vegetables) they are bulky for their caloric content. However, apple seeds are mildly poisonous, containing a small amount of amygdalin, a cyanogenic glycoside. It usually is not enough to be dangerous to humans, but can deter birds.
There is evidence from laboratory experiments that apples possess phenolic compounds which may be cancer-protective and demonstrate antioxidant activity. The predominant phenolic phytochemicals in apples are quercetin, epicatechin, and procyanidin B2.
Apple juice concentrate has been found to increase the production of the neurotransmitter acetylcholine in mice, providing a potential mechanism for the "prevention of the decline in cognitive performance that accompanies dietary and genetic deficiencies and aging." Other studies have shown an "alleviation of oxidative damage and cognitive decline" in mice after the administration of apple juice. Researchers at the Chinese University of Hong Kong discovered that fruit flies who were fed an apple extract lived 10% longer than other flies who were fed a normal diet.

Botanical information
Blossoms, fruits, and leaves of the apple tree (Malus domestica)
The apple forms a tree that is small and deciduous, reaching 3 to 12 metres (9.8 to 39 ft) tall, with a broad, often densely twiggy crown. The leaves are alternately arranged simple ovals 5 to 12 cm long and 3–6 centimetres (1.2–2.4 in) broad on a 2 to 5 centimetres (0.79 to 2.0 in) petiole with an acute tip, serrated margin and a slightly downy underside. Blossoms are produced in spring simultaneously with the budding of the leaves. The flowers are white with a pink tinge that gradually fades, five petaled, and 2.5 to 3.5 centimetres (0.98 to 1.4 in) in diameter. The fruit matures in autumn, and is typically 5 to 9 centimetres (2.0 to 3.5 in) in diameter. The center of the fruit contains five carpels arranged in a five-point star, each carpel containing one to three seeds, called pips.

Wild ancestors
Main article: Malus sieversii
The wild ancestors of Malus domestica are Malus sieversii, found growing wild in the mountains of Central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan, and Xinjiang, China, and possibly also Malus sylvestris.

Genome
In 2010, an Italian-led consortium announced they had decoded the complete genome of the apple, using the Golden delicious variety. It had about 57,000 genes, the highest number of any plant genome studied to date and more genes than the human genome (about 30,000). This new understanding of the apple genome will help scientists in identifying genes and gene variants that contribute to disease and drought resistance and other desirable characteristics. Understanding the genes behind these characteristics will allow scientists to perform more knowledgeable selective breeding. Decoding the genome also provided proof that Malus sieversii was the wild ancestor of the domestic apple - an issue that had been long-debated in the scientific community.

History
Wild Malus sieversii apple in Kazakhstan
The center of diversity of the genus Malus is in eastern Turkey. The apple tree was perhaps the earliest tree to be cultivated,[8] and its fruits have been improved through selection over thousands of years. Alexander the Great is credited with finding dwarfed apples in Kazakhstan in Asia in 328 BCE; those he brought back to Macedonia might have been the progenitors of dwarfing root stocks. Winter apples, picked in late autumn and stored just above freezing, have been an important food in Asia and Europe for millennia, as well as in Argentina and in the United States since the arrival of Europeans. Apples were brought to North America with colonists in the 17th century, and the first apple orchard on the North American continent was said to be near Boston in 1625. In the 20th century, irrigation projects in Washington state began and allowed the development of the multibillion dollar fruit industry, of which the apple is the leading species.
Until the 20th century, farmers stored apples in frostproof cellars during the winter for their own use or for sale. Improved transportation of fresh apples by train and road replaced the necessity for storage.

Apple cultivars
There are more than 7,500 known cultivars of apples. Cultivars vary in their yield and the ultimate size of the tree, even when grown on the same rootstock. Different cultivars are available for temperate and subtropical climates. One large collection of over 2,100 apple cultivars is housed at the National Fruit Collection in England. Most of these cultivars are bred for eating fresh (dessert apples), though some are cultivated specifically for cooking (cooking apples) or producing cider. Cider apples are typically too tart and astringent to eat fresh, but they give the beverage a rich flavour that dessert apples cannot.
Commercially popular apple cultivars are soft but crisp. Other desired qualities in modern commercial apple breeding are a colourful skin, absence of russeting, ease of shipping, lengthy storage ability, high yields, disease resistance, typical 'Red Delicious' apple shape, and popular flavour. Modern apples are generally sweeter than older cultivars, as popular tastes in apples have varied over time. Most North Americans and Europeans favour sweet, subacid apples, but tart apples have a strong minority following. Extremely sweet apples with barely any acid flavour are popular in Asia and especially India.
Old cultivars are often oddly shaped, russeted, and have a variety of textures and colours. Some find them to have a better flavour than modern cultivars, but may have other problems which make them commercially unviable, such as low yield, liability to disease, or poor tolerance for storage or transport. A few old cultivars are still produced on a large scale, but many have been kept alive by home gardeners and farmers that sell directly to local markets. Many unusual and locally important cultivars with their own unique taste and appearance exist; apple conservation campaigns have sprung up around the world to preserve such local cultivars from extinction. In the United Kingdom, old cultivars such as 'Cox's Orange Pippin' and 'Egremont Russet' are still commercially important even though by modern standards they are low yielding and disease prone.

Commerce
At least 55 million tonnes of apples were grown worldwide in 2005, with a value of about $10 billion. About two-fifths of this total was produced in China. More than 7.5% world production occurs in the United States.
In the United States, more than 60% of all the apples sold commercially are grown in Washington state. Imported apples from New Zealand and other more temperate areas are competing with US production and increasing each year.
Most of Australia's apple production is for domestic consumption. Imports from New Zealand have been disallowed under quarantine regulations for fireblight since 1921.
The largest exporters of apples in 2006 were China, Chile, Italy, France and the U.S., while the biggest importers in the same year were Russia, Germany, the UK and the Netherlands.

Human consumption
Apples are often eaten raw; except for the seeds, which are slightly poisonous (see below), the whole fruit including the skin is suitable for human consumption. Varieties bred for this purpose are termed dessert or table apples.
Apples can be canned or juiced. They are milled to produce apple cider (non-alcoholic, sweet cider) and filtered for apple juice. The juice can be fermented to make cider (alcoholic, hard cider), ciderkin, and vinegar. Through distillation, various alcoholic beverages can be produced, such as applejack, Calvados,[45] and apfelwein. Pectin and apple seed oil may also be produced.
Apples are an important ingredient in many desserts, such as apple pie, apple crumble, apple crisp and apple cake. They are often eaten baked or stewed, and they can also be dried and eaten or reconstituted (soaked in water, alcohol or some other liquid) for later use. Puréed apples are generally known as apple sauce. Apples are also made into apple butter and apple jelly. They are also used (cooked) in meat dishes.
In the UK, a toffee apple is a traditional confection made by coating an apple in hot toffee and allowing it to cool. Similar treats in the US are candy apples (coated in a hard shell of crystallised sugar syrup), and caramel apples, coated with cooled caramel.
Apples are eaten with honey at the Jewish New Year of Rosh Hashanah to symbolize a sweet new year.
Farms with apple orchards may open them to the public, so consumers may themselves pick the apples they will buy.
Sliced apples turn brown with exposure to air due to the conversion of natural phenolic substances into melanin upon exposure to oxygen. Different cultivars vary in their propensity to brown after slicing. Sliced fruit can be treated with acidulated water to prevent this effect.
Organic apples are commonly produced in the United States. Organic production is difficult in Europe, though a few orchards have done so with commercial success, using disease-resistant cultivars and the very best cultural controls. The latest tool in the organic repertoire is a spray of a light coating of kaolin clay, which forms a physical barrier to some pests, and also helps prevent apple sun scald.

Apple allergy
One form of apple allergy, often found in northern Europe, is called birch-apple syndrome, and is found in people who are also allergic to birch pollen. The allergy is caused by a protein in apples that is similar to birch pollen, and people affected by this protein can also become allergic to other fruits, nuts and vegetables. Reactions, which are called oral allergy syndrome (OAS), generally involve itching and inflammation of the mouth and throat, but in rare cases can also include life-threatening anaphylaxis. This reaction only occurs when raw fruit is consumed - the allergen is neutralized in the cooking process. The variety of apple, maturity and storage conditions can change the amount of allergen present in individual fruits. Long storage times can increase the amount of proteins that cause birch-apple syndrome.
In other areas, such as the Mediterranean, people have adverse reactions to apples because of their similarity to peaches, including a close relationship between the allergens of the two fruits. This form of apple allergy also includes OAS, but often has more severe symptoms, such as vomiting, abdominal pain and urticaria, and can be life-threatening. Individuals with this form of allergy can also develop reactions to other fruits and nuts. Cooking does not break down the protein causing this particular reaction, so affected individuals cannot each either raw or cooked apples. Freshly harvested, over-ripe fruits tend to have the highest levels of the protein that causes this reaction.
Breeding efforts have yet to produce a hypoallergenic fruit for either of the two types of apple allergy.