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How are Almonds Grown?
Almond is the name of a popular edible nut of the tree that bears it.
The tree is a member of the rose family, Rosaceae.
It has been in cultivation in eastern Mediterranean countries and the Middle East from very early times. Today it is widely grown in Spain, Italy, northern Africa, California (introduced about the middle of the 19th century), Australia, and southern Africa. Almonds are sold in greater quantities than any other nut.
Tree and Nut
Similar to the peach tree in appearance, the almond tree grows to about 25 feet, and its white or rose flowers, 1 1/2 to 2 inches across, appear early in spring. Unlike the peach, with its soft and juicy flesh, the flesh of the almond is dry and leathery. As this dry fruit (drupe) splits open, the seed with its thin brown coat (endocarp) is exposed. Commercial almonds consist of this thin, pitted, light-colored endocarp enclosing the seed or "kernel".
Several principal horticultural varieties of the tree, with innumerable forms, are generally recognized. In temperate climates the trees are usually selected for their flowers, which are often bright pink and double, rather than as bearers, whereas in warmer climates the trees are chosen for the quality of their nuts.
For commercial purposes, almonds are usually graded according to the thickness of the shell as paper-shelled, soft-shelled, and thick-shelled.
Normally, two main classes of almonds are recognized: the sweet (variety dulcis) for confectionery and dessert, and the bitter (variety amara) used for making oil and flavoring.
Successful cultivation of good bearers requires deep soil, a suitable warm climate with adequate rainfall (16 to 40 inches per year), and cross-pollination, as most varieties are self-sterile. Since honeybees are the most important pollinators, hives of bees are sometimes placed in the orchards at flowering time to increase the crop.
Over a hundred varieties, imported and new, are grown in California. The bitter almond tree is often used as a stock on which sweet almond and other fruits are grafted or budded.
Almond oil is volatile. It usually is derived from dried ripe kernels of bitter almond, apricot, and peach.
It contains amygdalin (C20H27NO11), a sugar derivative, which yields a sugar plus benzaldehyde and hydrocyanic acid with the addition of the enzyme emulsin.
The hydrocyanic acid accounts for the bitter taste of bitter almond, and the benzaldehyde is responsible for the typical almond flavor. Sugar derivatives such as amygdalin, which yield cyanides, are not used widely in pharmacy and medicine because of the dangerous properties of hydrocyanic acid. They are used, however, as sedatives in cough syrups and similar preparations. Sweet almonds usually contain 44 to 55 percent oil, whereas bitter almonds contain 38 to 45 percent.
The oil is generally prepared from bitter almonds since they are cheaper than sweet almonds, which are preferred for eating.
In addition to these differences in taste and contents, bitter almonds are shorter and wider than sweet almonds.