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Friday, December 17, 2010

Extraction of argan oil

Traditional method
The production of argan oil by traditional methods

For modern times, the Berbers (indigenous people of Morocco) of this area would collect undigested argan pits from the waste of goats which climb the trees to eat their fruit. The pits were then ground and pressed to make the nutty oil used in cooking and cosmetics. However, the oil used in cosmetic and culinary products available for sale today has most likely been harvested and processed with machines in a verifiably clean and sanitary way.

The oil was sold in Moroccan markets even before the Phoenicians arrived, yet the hardy argan tree has been slowly disappearing. Overgrazing by goats and a growing, wood-hungry local population have whittled the number of surviving trees down to less than half of what it was 50 years ago.

The tree is a relic of the Earth's Tertiary Period, which ended about 1.6 million years ago, and it grows in only a few other places in the world. It is tenacious, withering and fruitless during extended droughts, and it lives as long as 200 years. So there was alarm that the Argania spinosa, as the tree is properly called, was headed for extinction, along with its precious goat-related oil.

UNESCO, and enthusiasts excited by the oil's reputed anti-aging qualities have helped by creating a global market for the exotic oil, the unlikely alliance hopes to raise awareness about the inherent value of the trees, encouraging more careful grazing and stopping the local population from chopping the trees down for firewood. The people in the area are poor; as they now understand the value of the tree, they are protecting it.

UNESCO declared a 25,900-square-kilometer of land between the Atlantic and the Atlas Mountains a reserve and provided money to manage the trees' preservation. Chefs and society matrons took up the cause, praising the culinary qualities of the oil and its anti-aging effect on the skin. There is also a ban against grazing in the trees from May to August, when the fruit ripens to a bright yellow and eventually the goats climb the trees, eat the fruit and expel the pits, which locals continue to collect.

At the Cooperative in Tiout, Berber women sit on the floor with rough rectangular stones between their knees cracking pits with rounded rocks. Each smooth pit contains one to three kernels, which look like sliced almonds and are rich in oil. The kernels are then removed and gently roasted. This roasting accounts for part of the oil's distinctive, nutty flavour. It takes several days and about 32 kilograms of fruit - roughly one season's produce from a single tree - to make only one liter of oil. The cosmetic oil, rich in vitamin E and essential fatty acids, is used for massage, facials and as an ingredient in anti-aging cream. The edible oil is extracted from roasted kernels.

Most of the oil is bottled pure for cooking, as a dressing on salads, meat or fish or simply as a dip for bread. The Tiout cooperative produces about 5,000 250-milliliter bottles of the edible oil a year. The oil can be purchased at the Cooperative in Tiout but the neighbouring city of Agadir sells the oil for a fair price as well.

Press-extraction

Now increasingly important for oil produced for sale, as the oil will keep 12–18 months and extraction is much faster. Using mechanical presses, mixing of the dough and water is unnecessary and the dough can be directly pressed. All other steps remaining unchanged, the oil is obtained in about 43% yield (calculated from the kernels) and only two hours are needed to get one litre of oil that preserves correctly.

Solvent-extraction

For industrial or laboratory purposes, argan oil can be extracted from ground kernels using any volatile lipophilic solvent. After evaporation of this latter, and one or two cycles of extraction, the oil is obtained in 50 to 55% yield. This type of extraction furnishes an oil with unsatisfactory organoleptic properties compared to the traditional or press extraction, which is exclusively reserved to prepare argan oil for cosmetic purposes

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