The avocado tree (Persea americana mill.) belongs to the genus Persea and family Laureaceae. It reaches about 4-20 metres in height, with a diameter of about 0.6 meter. It is a year-round green tree with a smooth grey bark. The avocado fruit itself is considered a berry. For sufficient growth the plant needs a light-intensive and frost-free location, as well as a nutrient-rich soil with plenty of moisture. Since too much moisture would lead to root rot, plantations are irrigated at intervals. Although over 200 varieties are known worldwide only the Fuerte and Hass varieties are cultivated. The plant has monoecious flowers that appear and ripen at uneven times of the day. Hence no pollination takes place as the male and female reproductive organs are never open. at the same time. To avoid this, plants are grown at each location with alternating maturity. It takes the tree 6 - 10 years to flower which makes a subsequent crop rotation possible.
Avocado cultivation takes place mainly in tropical and subtropical climates, especially in Asia and America. The main producers worldwide include Mexico, Peru, the Dominican Republic and Indonesia.
The fruits are harvested carefully by hand and mechanically. Time of harvesting is essential for the oil yield since the content increases from 10 % at the beginning up to 25 %.
There are several methods of avocado oil production (extraction, pressing, others), although they may differ in the way fruit is processed (with or without skin).
A frequently used method is the cold pressing process. For this the skin and pit are separated from the fruit and the resulting pulp is smashed. In earlier processes, water was removed from the pulp to obtain the oil. Today water is added separately in order to achieve a higher yield. This is probably due to more effective cell destruction whereby the oil can leak easier and then re-agglomerate extracellularly. The oil is now separated from the water and solids in several centrifuges and finally refined/ purified as required.
Further processes are: Extraction methods using organic solvents/supercritical gases or ultrasonic digestion.
The oil has a high content of monounsaturated fatty acids, sterols, amino acids and vitamins.
The pharmaceutical and cosmetics industry uses the oil as a basis for skin care products for dry and irritated skin. Avocado oil shows a good penetration capacity on the skin (comparison: peanut oil completely lacks penetration capacity) which is why its application is suitable for dry skin. The skin becomes moisturized, smooth and soft (hydrating effect).
Its cell-generating and pain-relieving effect also makes the oil attractive in medical treatment of scars, skin damage, eczema, psoriasis or neurodermatitis.
Used for example as cooking oil it can reduce cholesterol levels with the help of plant sterols and fatty acids.
Skin and pit are removed mechanically before pressing where parts of the skin can remain in the process. (about 90 % of the skin can be removed). If the oil is not further refined, it shows in increased levels of chlorophyll. If there is too much chlorophyll in the oil, rapid oxidation can occur when exposed to light and thus lead to a reduction in quality (altered sensory/ olfactory parameters).
Another chemical substance, the so-called persin, is responsible for the insecticidal and fungicidal effect and shows harmful effects on health. This substance is however degraded enzymatically during the ripening process which enables consumption of the pulp.