Malus ( /ˈmeɪləs/^[2] or /ˈmæləs/), the apples, are a genus of about 30–35 species of small deciduous trees or shrubs in the family Rosaceae. Other studies go as far as 55 species^[3] including the domesticated Orchard Apple, or Table apple as it was formerly called (M. domestica, derived from M. sieversii, syn. M. pumila). The other species and subspecies are generally known as "wild apples", "crab apples", "crabapples" or "crabs".

The genus is native to the temperate zone of the Northern Hemisphere, in Europe, Asia and North America.

Apple trees are typically 4–12 m tall at maturity, with a dense, twiggy crown. The leaves are 3–10 cm long, alternate, simple, with a serrated margin. The flowers are borne in corymbs, and have five petals, which may be white, pink or red, and are perfect, with usually red stamens that produce copious pollen, and a half-inferior ovary; flowering occurs in the spring after 50–80 growing degree days (varying greatly according to subspecies and cultivar).

Flowering crabapple blooms

Apples require cross-pollination between individuals by insects (typically bees, which freely visit the flowers for both nectar and pollen); all are self-sterile, and (with the exception of a few specially developed cultivars) self-pollination is impossible, making pollinating insects essential. Malus species, including domestic apples, hybridize freely. Malus species are used as food plants by the larvae of a large number of Lepidoptera species; see list of Lepidoptera that feed on Malus.

Crabapple fruit are mostly red,^[4] but some, such as this cultivar 'Golden Hornet', are yellow

The fruit is a globose pome, varying in size from 1–4 cm diameter in most of the wild species, to 6 cm in M. sylvestris sieversii, 8 cm in M. sylvestris domestica, and even larger in certain cultivated orchard apples; among the largest-fruited cultivars (all of which originate in North America) are 'Wolf River' and 'Stark Jumbo' . The centre of the fruit contains five carpels arranged star-like, each containing one to two (rarely three) seeds.

One species, Malus trilobata from southwest Asia, has three- to seven-lobed leaves (superficially resembling a maple leaf) and with several structural differences in the fruit; it is often treated in a genus of its own, as Eriolobus trilobatus.

Uses

For Malus sylvestris domestica, see Apple. The fruit of the other species is not an important crop in most areas, being extremely sour and (in some species) woody, and is rarely eaten raw for this reason. In some southeast Asian cultures they are valued as a sour condiment, sometimes eaten with salt and chili pepper, or shrimp paste.

Crabapples are an excellent source of pectin, and their juice can be made into a ruby-coloured preserve with a full, spicy flavor.^[5] A small percentage of crabapples in cider makes a more interesting flavour.^{[citation needed]} As Old English Wergulu, the crab apple is one of the nine plants invoked in the pagan Anglo-Saxon Nine Herbs Charm, recorded in the 10th century.

Crabapples are widely grown as ornamental trees, grown for their beautiful flowers or fruit, with numerous cultivars selected for these qualities and for resistance to disease.

Some crabapples are used as rootstocks for domestic apples to add beneficial characteristics.^[6] For example, varieties of Baccata, also called Siberian crab, rootstock is used to give additional cold hardiness to the combined plant for orchards in cold northern areas.^[7]

They are also used as pollinizers in apple orchards. Varieties of crabapple are selected to bloom contemporaneously with the apple variety in an orchard planting, and the crabs are planted every sixth or seventh tree, or limbs of a crab tree are grafted onto some of the apple trees. In emergencies, a bucket or drum bouquet of crabapple flowering branches are placed near the beehives as orchard pollenizers. See also Fruit tree pollination. Because of the plentiful blossoms and small fruit, crabapples are popular for use in bonsai culture; however, because the tiny trees still show the abundant, full-sized fruit of normal crabapples, it is important to thin out the fruit so that the trees do not exhaust themselves.

The Chestnut Crabapple is an exception in that its fruit is sweet tasting.^{[citation needed]} A very hardy plant, the Chestnut Crabapple blooms in early to mid-May and is an excellent pollinator for other fruit apples. It produces a very large crabapple, up to 2" (5 cm) in diameter, that ripens in early September with a pleasant nut-like flavor and good texture for fresh eating. The fruit quality holds well on the tree, being quite spritely at first and becoming sweeter later on, with a medium storage life.

Apple wood gives off a pleasant scent when burned, and smoke from an apple wood fire gives an excellent flavour to smoked foods.^[8] It is easier to cut when green; dry apple wood is exceedingly difficult to carve by hand ^[8] It is a good wood for cooking fires because it burns hot and slow, without producing much flame.^[8]

Species

Cultivars

Notes

References

Wikimedia Commons has media related to: Malus

• Germplasm Resources Information Network: Malus
• Flora of China: Malus
• Virginia Cooperative Extension - Disease resistant crabapples
• Ontario Ministry of Agriculture and Food - Crabapple pollenizers for apples
• The PRI disease resistant apple breeding program: a cooperative among Purdue University, Rutgers University, and the University of Illinois.
• Germplasm Resources Information Network: Diab

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. Apples 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 America 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.

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.^[2] 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.^[2]

Wild ancestors

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,^[3] and possibly also Malus sylvestris.^[4]

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^[5] and more genes than the human genome (about 30,000).^[6] 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.^[7]

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;^[2] 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.^[8] Apples were brought to North America with colonists in the 17th century,^[2] 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.^[2]

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.^[9][10] In the 21st century, long-term storage again came into popularity, as "controlled atmosphere" facilities were used to keep apples fresh year-round. Controlled atmosphere facilities use high humidity and low oxygen and carbon dioxide levels to maintain fruit freshness.^[11]

Cultural aspects

"Brita as Iduna" (1901) by Carl Larsson

Germanic paganism

In Norse mythology, the goddess Iðunn is portrayed in the Prose Edda (written in the 13th century by Snorri Sturluson) as providing apples to the gods that give them eternal youthfulness. English scholar H. R. Ellis Davidson links apples to religious practices in Germanic paganism, from which Norse paganism developed. She points out that buckets of apples were found in the Oseberg ship burial site in Norway, and that fruit and nuts (Iðunn having been described as being transformed into a nut in Skáldskaparmál) have been found in the early graves of the Germanic peoples in England and elsewhere on the continent of Europe, which may have had a symbolic meaning, and that nuts are still a recognized symbol of fertility in southwest England.^[12]

Davidson notes a connection between apples and the Vanir, a tribe of gods associated with fertility in Norse mythology, citing an instance of eleven "golden apples" being given to woo the beautiful Gerðr by Skírnir, who was acting as messenger for the major Vanir god Freyr in stanzas 19 and 20 of Skírnismál. Davidson also notes a further connection between fertility and apples in Norse mythology in chapter 2 of the Völsunga saga when the major goddess Frigg sends King Rerir an apple after he prays to Odin for a child, Frigg's messenger (in the guise of a crow) drops the apple in his lap as he sits atop a mound.^[13] Rerir's wife's consumption of the apple results in a six-year pregnancy and the Caesarean section birth of their son - the hero Völsung.^[14]

Further, Davidson points out the "strange" phrase "Apples of Hel" used in an 11th century poem by the skald Thorbiorn Brúnarson. She states this may imply that the apple was thought of by the skald as the food of the dead. Further, Davidson notes that the potentially Germanic goddess Nehalennia is sometimes depicted with apples and that parallels exist in early Irish stories. Davidson asserts that while cultivation of the apple in Northern Europe extends back to at least the time of the Roman Empire and came to Europe from the Near East, the native varieties of apple trees growing in Northern Europe are small and bitter. Davidson concludes that in the figure of Iðunn "we must have a dim reflection of an old symbol: that of the guardian goddess of the life-giving fruit of the other world."^[12]

Greek mythology

Heracles with the apple of Hesperides

Apples appear in many religious traditions, often as a mystical or forbidden fruit. One of the problems identifying apples in religion, mythology and folktales is that the word "apple" was used as a generic term for all (foreign) fruit, other than berries, but including nuts, as late as the 17th century.^[15] For instance, in Greek mythology, the Greek hero Heracles, as a part of his Twelve Labours, was required to travel to the Garden of the Hesperides and pick the golden apples off the Tree of Life growing at its center.^[16][17][18]

The Greek goddess of discord, Eris, became disgruntled after she was excluded from the wedding of Peleus and Thetis.^[19] In retaliation, she tossed a golden apple inscribed Καλλίστη (Kalliste, sometimes transliterated Kallisti, 'For the most beautiful one'), into the wedding party. Three goddesses claimed the apple: Hera, Athena, and Aphrodite. Paris of Troy was appointed to select the recipient. After being bribed by both Hera and Athena, Aphrodite tempted him with the most beautiful woman in the world, Helen of Sparta. He awarded the apple to Aphrodite, thus indirectly causing the Trojan War.

The apple was thus considered, in ancient Greece, to be sacred to Aphrodite, and to throw an apple at someone was to symbolically declare one's love; and similarly, to catch it was to symbolically show one's acceptance of that love.^[20] An epigram claiming authorship by Plato states:

I throw the apple at you, and if you are willing to love me, take it and share your girlhood with me; but if your thoughts are what I pray they are not, even then take it, and consider how short-lived is beauty.

—Plato, Epigram VII^[21]

Atalanta, also of Greek mythology, raced all her suitors in an attempt to avoid marriage. She outran all but Hippomenes (a.k.a. Melanion, a name possibly derived from melon the Greek word for both "apple" and fruit in general),^[17] who defeated her by cunning, not speed. Hippomenes knew that he could not win in a fair race, so he used three golden apples (gifts of Aphrodite, the goddess of love) to distract Atalanta. It took all three apples and all of his speed, but Hippomenes was finally successful, winning the race and Atalanta's hand.^[16]

The Apple in the Garden of Eden

Adam and Eve
Showcasing the apple as a symbol of sin.
Albrecht Dürer, 1507

Though the forbidden fruit in the Book of Genesis is not identified, popular Christian tradition has held that it was an apple that Eve coaxed Adam to share with her.^[22] This may have been the result of Renaissance painters adding elements of Greek mythology into biblical scenes (alternative interpretations also based on Greek mythology occasionally replace the apple with a pomegranate). In this case the unnamed fruit of Eden became an apple under the influence of story of the golden apples in the Garden of Hesperides. As a result, in the story of Adam and Eve, the apple became a symbol for knowledge, immortality, temptation, the fall of man into sin, and sin itself. In Latin, the words for "apple" and for "evil" are similar (mālum "an apple", mălum "an evil, a misfortune"). This may also have influenced the apple becoming interpreted as the biblical "forbidden fruit". The larynx in the human throat has been called Adam's apple because of a notion that it was caused by the forbidden fruit sticking in the throat of Adam.^[22] The apple as symbol of sexual seduction has been used to imply sexuality between men, possibly in an ironic vein.^[22]

Apple cultivars

There are more than 7,500 known cultivars of apples.^[23] Cultivars vary in their yield and the ultimate size of the tree, even when grown on the same rootstock.^[24] Different cultivars are available for temperate and subtropical climates. One large collection of over 2,100^[25] 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.^[26]

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.^[24] 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.^[27] Extremely sweet apples with barely any acid flavour are popular in Asia^[27] and especially India.^[26]

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,^[28] 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.^[2]

Apple production

Apple breeding

Apple pot

In the wild, apples grow quite readily from seeds. However, like most perennial fruits, apples are ordinarily propagated asexually by grafting. This is because seedling apples are an example of "extreme heterozygotes", in that rather than inheriting DNA from their parents to create a new apple with those characteristics, they are instead different from their parents, sometimes radically.^[29] Triploids have an additional reproductive barrier in that the 3 sets of chromosomes cannot be divided evenly during meiosis, yielding unequal segregation of the chromosomes (aneuploids). Even in the very unusual case when a triploid plant can produce a seed (apples are an example), it happens infrequently, and seedlings rarely survive.^[30] Most new apple cultivars originate as seedlings, which either arise by chance or are bred by deliberately crossing cultivars with promising characteristics.^[31] The words 'seedling', 'pippin', and 'kernel' in the name of an apple cultivar suggest that it originated as a seedling. Apples can also form bud sports (mutations on a single branch). Some bud sports turn out to be improved strains of the parent cultivar. Some differ sufficiently from the parent tree to be considered new cultivars.^[32]

The Excelsior Experiment Station of the University of Minnesota has, since the 1930s, introduced a steady progression of important hardy apples that are widely grown, both commercially and by backyard orchardists, throughout Minnesota and Wisconsin. Its most important introductions have included 'Haralson' (which is the most widely cultivated apple in Minnesota), 'Wealthy', 'Honeygold', and 'Honeycrisp'.

Apples have been acclimatized in Ecuador at very high altitudes, where they provide crops twice per year because of constant temperate conditions in a whole year.^[33]

Apple rootstocks

Rootstocks used to control tree size have been used in apple cultivation for over 2,000 years. Dwarfing rootstocks were probably discovered by chance in Asia. Alexander the Great sent samples of dwarf apple trees back to his teacher, Aristotle, in Greece. They were maintained at the Lyceum, a center of learning in Greece.

Most modern apple rootstocks were bred in the 20th century. Much research into the existing rootstocks was begun at the East Malling Research Station in Kent, England. Following that research, Malling worked with the John Innes Institute and Long Ashton to produce a series of different rootstocks with disease resistance and a range of different sizes, which have been used all over the world.

Pollination

Apple blossom from an old Ayrshire variety

Orchard mason bee on apple bloom, British Columbia, Canada

Apples are self-incompatible; they must cross-pollinate to develop fruit. During the flowering each season, apple growers usually provide pollinators to carry the pollen. Honey bees are most commonly used. Orchard mason bees are also used as supplemental pollinators in commercial orchards. Bumblebee queens are sometimes present in orchards, but not usually in enough quantity to be significant pollinators.^[32]

There are four to seven pollination groups in apples, depending on climate:

• Group A – Early flowering, May 1 to 3 in England (Gravenstein, Red Astrachan)
• Group B – May 4 to 7 (Idared, McIntosh)
• Group C – Mid-season flowering, May 8 to 11 (Granny Smith, Cox's Orange Pippin)
• Group D – Mid/late season flowering, May 12 to 15 (Golden Delicious, Calville blanc d'hiver)
• Group E – Late flowering, May 16 to 18 (Braeburn, Reinette d'Orléans)
• Group F – May 19 to 23 (Suntan)
• Group H – May 24 to 28 (Court-Pendu Gris) (also called Court-Pendu plat)

One cultivar can be pollinated by a compatible cultivar from the same group or close (A with A, or A with B, but not A with C or D).^[34]

Varieties are sometimes classed as to the day of peak bloom in the average 30 day blossom period, with pollinizers selected from varieties within a 6 day overlap period.

Maturation and harvest

Cultivars vary in their yield and the ultimate size of the tree, even when grown on the same rootstock. Some cultivars, if left unpruned, will grow very large, which allows them to bear much more fruit, but makes harvesting very difficult. Mature trees typically bear 40–200 kilograms (88–440 lb) of apples each year, though productivity can be close to zero in poor years. Apples are harvested using three-point ladders that are designed to fit amongst the branches. Dwarf trees will bear about 10–80 kilograms (22–180 lb) of fruit per year.^[32]

Storage

Commercially, apples can be stored for some months in controlled-atmosphere chambers to delay ethylene-induced onset of ripening. The apples are commonly stored in chambers with higher concentrations of carbon dioxide and high air filtration. This prevents ethylene concentrations from rising to higher amounts and preventing ripening from moving too quickly. Ripening continues when the fruit is removed.^[35] For home storage, most varieties of apple can be held for approximately two weeks when kept at the coolest part of the refrigerator (i.e. below 5 °C). Some types, including the Granny Smith and Fuji, can be stored up to a year without significant degrade.^[36][37]

Pests and diseases

Leaves with significant insect damage

The trees are susceptible to a number of fungal and bacterial diseases and insect pests. Many commercial orchards pursue an aggressive program of chemical sprays to maintain high fruit quality, tree health, and high yields. A trend in orchard management is the use of organic methods. These use a less aggressive and direct methods of conventional farming. Instead of spraying potent chemicals, often shown to be potentially dangerous and maleficent to the tree in the long run, organic methods include encouraging or discouraging certain cycles and pests. To control a specific pest, organic growers might encourage the prosperity of its natural predator instead of outright killing it, and with it the natural biochemistry around the tree. Organic apples generally have the same or greater taste than conventionally grown apples, with reduced cosmetic appearances.^[38]

A wide range of pests and diseases can affect the plant; three of the more common diseases/pests are mildew, aphids and apple scab.

• Mildew: which is characterized by light grey powdery patches appearing on the leaves, shoots and flowers, normally in spring. The flowers will turn a creamy yellow colour and will not develop correctly. This can be treated in a manner not dissimilar from treating Botrytis; eliminating the conditions which caused the disease in the first place and burning the infected plants are among the recommended actions to take.^[39][39]

• Aphids: There are five species of aphids commonly found on apples: apple grain aphid, rosy apple aphid, apple aphid, spirea aphid and the woolly apple aphid. The aphid species can be identified by their colour, the time of year when they are present and by differences in the cornicles, which are small paired projections from the rear of aphids.^[39] Aphids feed on foliage using needle-like mouth parts to suck out plant juices. When present in high numbers, certain species reduce tree growth and vigor.^[40]

• Apple scab: Apple scab causes leaves to develop olive-brown spots with a velvety texture that later turn brown and become cork-like in texture. The disease also affects the fruit, which also develops similar brown spots with velvety or cork-like textures. Apple scab is spread through fungus growing in old apple leaves on the ground and spreads during warm spring weather to infect the new year's growth.^[41]

Among the most serious disease problems are fireblight, a bacterial disease; and Gymnosporangium rust, and black spot, two fungal diseases.^[40] Codling moths and apple maggots are two other pests which affect apple trees. Young apple trees are also prone to mammal pests like mice and deer, which feed on the soft bark of the trees, especially in winter.^[41]

Commerce

Apple output in 2005

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.^[42] More than 7.5% world production occurs in the United States.^[31]

In the United States, more than 60% of all the apples sold commercially are grown in Washington state.^[43] Imported apples from New Zealand and other more temperate areas are competing with US production and increasing each year.^[42]

Most of Australia's apple production is for domestic consumption. Imports from New Zealand have been disallowed under quarantine regulations for fireblight since 1921.^[44]

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.^[45]

Top ten apple producers — 11 June 2008

Country	Production (tonnes)	Footnote
People's Republic of China	27 507 000	F
United States	4 237 730
Iran	2 660 000	F
Turkey	2 266 437
Russia	2 211 000	F
Italy	2 072 500
India	2 001 400
France	1 800 000	F
Chile	1 390 000	F
Argentina	1 300 000	F
World	64 255 520	A
No symbol = official figure, F = FAO estimate, A = Aggregate (may include official, semi-official, or estimates); Source: FAO

Human consumption

Different kinds of apple cultivars in a supermarket

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,^[46] 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.^[46]
• Farms with apple orchards may open them to the public, so consumers may themselves pick the apples they will buy.^[46]

Sliced apples turn brown with exposure to air due to the conversion of natural phenolic substances into melanin upon exposure to oxygen.^[47] Different cultivars vary in their propensity to brown after slicing.^[48] Sliced fruit can be treated with acidulated water to prevent this effect.^[47]

Organic apples are commonly produced in the United States.^[49] Organic production is difficult in Europe, though a few orchards have done so with commercial success,^[49] 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.^[32][49]

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,^[50] but in rare cases can also include life-threatening anaphylaxis.^[51] 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.^[50]

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 eat either raw or cooked apples. Freshly harvested, over-ripe fruits tend to have the highest levels of the protein that causes this reaction.^[50]

Breeding efforts have yet to produce a hypoallergenic fruit for either of the two types of apple allergy.^[50]

Nutrition

Health benefits of apple consumption.^{[52][53][54][55]}

The proverb "An apple a day keeps the doctor away.", addressing the health effects of the fruit, dates from 19th century Wales.^[56] Research suggests that apples may reduce the risk of colon cancer, prostate cancer and lung cancer.^[52] Compared to many other fruits and vegetables, apples contain relatively low amounts of vitamin C, but are a rich source of other antioxidant compounds.^[47] 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,^[57] weight loss,^[57] 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.^[54][57] 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.^[58]

There is evidence from laboratory experiments that apples possess phenolic compounds which may be cancer-protective and demonstrate antioxidant activity.^[59] The predominant phenolic phytochemicals in apples are quercetin, epicatechin, and procyanidin B2.^[60]

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.^[55] 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.^[61]

References

This article incorporates text from the public domain 1911 edition of The Grocer's Encyclopedia.

Further reading

Books

• Browning, F. (1999). Apples: The Story of the Fruit of Temptation. North Point Press. ISBN 9780865475793
• Mabberley, D.J. / Juniper, B.E. (2009). The Story of the Apple. Timber Press. ISBN 9781604691726

Review articles on possible health benefits

• Gerhauser, C. “Cancer chemopreventive potential of apples, apple juice, and apple components”, Planta Medica (2008),74(13):1608-1624.
• Hyson, D.A. “A Comprehensive Review of Apples and Apple Components and Their Relationship to Human Health”, Advances in Nutrition. An International Review Journal (2011),2(5):408-420.

Malus x. domestica 'Zestar!'
Details
Hybrid parentage	'State Fair' & 'MN 1691'
Cultivar	'Zestar!'
Origin	University of Minnesota, 1998

Overview

The Zestar (known in the UK as the Flavar) is an apple cultivar that was released in 1998; it was bred to be sold as an early season apple able to survive in colder climates like Minnesota.^[1][2] (Malus, x domestica 'Zestar!')^[3]

This apple is protected under the US Plant Patent Act #97120.^[4]

See also

• Horticulture

References