The avocado (Persea americana) is a tree native to the Caribbean, Mexico, South America and Central America, classified in the flowering plant family Lauraceae along with cinnamon, camphor and bay laurel. Avocado or alligator pear also refers to the fruit (technically a large berry that contains a large seed) of the tree, which may be pear-shaped, egg-shaped or spherical.
Avocados are a commercially valuable fruit and are cultivated in tropical climates throughout the world (and some temperate ones, such as California), producing a green-skinned, pear-shaped fruit that ripens after harvesting. Trees are partially self-pollinating and often are propagated through grafting to maintain a predictable quality and quantity of the fruit.
P. americana, or the avocado, originated in the state of Puebla, Mexico. The native, undomesticated variety is known as a criollo, and is small, with dark black skin, and contains a large seed. The oldest evidence of avocado use was found in a cave located in Coxcatlán, Puebla, Mexico that dates to around 10,000 years BC. The avocado tree also has a long history of cultivation in Central and South America; a water jar shaped like an avocado, dating to AD 900, was discovered in the pre-Incan city of Chan Chan. The earliest known written account of the avocado in Europe is that of Martín Fernández de Enciso (c. 1470–c. 1528) in 1518 or 1519 in his book, Suma De Geographia Que Trata De Todas Las Partidas Y Provincias Del Mundo… The first written record in English of the use of the word ‘avocado’ was by Hans Sloane in a 1696 index of Jamaican plants. The plant was introduced to Indonesia in 1750, Brazil in 1809, the Levant in 1908, and South Africa and Australia in the late 19th century.
The word ‘avocado’ comes from the Nahuatl word ahuacatl (‘testicle’, a reference to the shape of the fruit). Avocados were known by the Aztecs as ‘the fertility fruit’. In some countries of South America, such as Argentina, Bolivia, Chile, Peru, and Uruguay, the avocado is known by its Quechua name, palta. In other Spanish-speaking countries, it is called aguacate, and in Portuguese it is abacate. The fruit is sometimes called an avocado pear or alligator pear (due to its shape and the rough green skin of some cultivars). The Nahuatl ahuacatl can be compounded with other words, as in ahuacamolli, meaning ‘avocado soup or sauce’, from which the Mexican Spanish word guacamole derives.
Also in some South American countries, the avocado is called manzana del invierno, which translates as ‘winter apple’
The fruit of horticultural cultivars has a markedly higher fat content than most other fruit, mostly monounsaturated fat, and as such serves as an important staple in the diet of various groups where access to other fatty foods (high-fat meats and fish, dairy, etc.) is limited.
A ripe avocado yields to gentle pressure when held in the palm of the hand and squeezed. The flesh is prone to enzymatic browning and turns brown quickly after exposure to air. To prevent this, lime or lemon juice can be added to avocados after they are peeled.
Avocados are high in valuable fats and appear to have a beneficial effect on blood serum levels. For a typical avocado:
* About 75% of an avocado's calories come from fat, most of which is monounsaturated fat. * Avocados also have 60% more potassium than bananas. They are rich in B vitamins, as well as vitamin E and vitamin K. * Avocados have a high fiber content among fruits - including 75% insoluble and 25% soluble fiber * A fatty triol (fatty alcohol) with one double bond, avocadene (16-heptadecene-1,2,4-triol), is found in avocado.
High avocado intake has been shown to have a beneficial effect on blood serum cholesterol levels. Specifically, after a seven-day diet rich in avocados, hypercholesterolemia patients showed a 17% decrease in total serum cholesterol levels. These subjects also showed a 22% decrease in both LDL (harmful cholesterol) and triglyceride levels and 11% increase in HDL (helpful cholesterol) levels. Additionally a Japanese team synthesised the four chiral components and identified (2R, 4R)-16-heptadecene-1, 2, 4-triol as the natural antibacterial component.
While not particularly popular, the avocado tree can be grown domestically and be used as a (decorative) houseplant. Typically, the pit germinates in either normal soil conditions or, alternatively, partially submerged in a container of water. If the grower chooses the latter method, the pit sprouts in four to six weeks, at which time it is planted in fertile soil such as potting soil. The plant generally grows large enough to be prunable, however, it does not bear fruit unless it has ample sunlight. Home gardeners can graft a branch from a fruit-bearing plant to speed maturity of the plant which typically take 4–6 years to bear fruit.
Toxicity to animals
There is documented evidence that animals such as cats, dogs, cattle, goats, rabbits, rats, birds, fish, and horses can be severely harmed or even killed when they consume the avocado leaves, bark, skin, or pit. The avocado fruit is poisonous to some birds, and the ASPCA and many other sites list it as toxic to many animals including cats, dogs, and horses. Avocado is an ingredient in AvoDerm dog food and cat food. However, the ASPCA has declined to say whether this food is safe or not.
Avocado leaves contain a toxic fatty acid derivative known as persin, which in sufficient quantity can cause equine colic and, without veterinary treatment, death. The symptoms include gastrointestinal irritation, vomiting, diarrhea, respiratory distress, congestion, fluid accumulation around the tissues of the heart, and even death. Birds also seem to be particularly sensitive to this toxic compound. Feeding avocados or guacamole to any non-human animal should be avoided completely. Negative effects in humans seem to be primarily in allergic individuals.