The macadamia nut is the fruit of a tree that is thought to have originated in Australia, probably in the state of Queensland in the northern part of the country. The nut of the macadamia tree has been eaten by Australian aborigines since ancient times. Ferdinand van Mueller, a European who first discovered this nut around 1850, named it the macadamia in honour of the Australian naturalist John Macadam. The Europeans who settled in Australia were quick to develop a taste for the macadamia nut, but it did not become a commercially important food until the early 20th century in Hawaii, where it was successfully introduced at the end of the 19th century. The Australians began to cultivate the macadamia nut intensively several decades later, and like Hawaii, Australia is now a leading producer of macadamia nuts.
There are half a dozen different species of macadamia trees, which grow in very humid environments and are sensitive to the cold as well as to changes in temperature. The macadamia tree can be up to 65 feet high, and its tough evergreen leaves are dark green in colour. The small nuts, which grow in bunches of about 20, are approximately 1 inch in diameter and fall to the ground when fully grown.
The macadamia nut consists of an off-white kernel enclosed in a brownish shell that is smooth, thick, and very hard. The shell itself is enclosed in a thin, fleshy green membrane that cracks open when the nut is fully grown and has to be completely removed before the shell can be broken. Ripe macadamia nuts are crunchy, flavourful, and hold up better than underripe nuts when cooked.
Macadamia nuts are generally fatty, smooth, sweet, and flavourful, but these characteristics vary from one species to another. Their flavour, which is similar to that of coconuts, is largely dependent on how much oil they contain. The lower amount of oil, the heavier, darker, and less flavorful the nut. Fattier nuts are generally plump, smooth, and relatively pale. The nuts are sorted by floating them in water and then dried naturally in the open air; they are shelled and cooked in one of two ways, depending on their fat content. The oiliest nuts are dry-roasted, and the others are plunged into hot oil, which improves their appearance but increases their already considerable fat content.