Macadamia is a genus of four species of trees indigenous to Australia and constituting part of the plant family Proteaceae. They grow naturally in north eastern New South Wales and central and south eastern Queensland, Australia. Common names include macadamia, macadamia nut, Queensland nut, bush nut, maroochi nut, queen of nuts and bauple nut; and from Indigenous Australians' languages bauple, gyndl, jindilli, and boombera. Previously, more species, with disjunct distributions, were named as members of this genus Macadamia.
Macadamia species grow as small to large evergreen trees 2–12 m tall. The leaves are arranged in whorls of three to six, lanceolate to obovate or elliptical in shape, 6–30 cm long and 2–13 cm broad, with an entire or spiny-serrated margin. The flowers are produced in a long, slender, simple raceme 5–30 cm long, the individual flowers 10–15 mm long, white to pink or purple, with four tepals. The fruit is a very hard, woody, globose follicle with a pointed apex, containing one or two seeds.
The seeds are a valuable food crop. Only three of the species, Macadamia integrifolia, Macadamia ternifolia, and Macadamia tetraphylla, are of commercial importance. Only 2 of these 3 species can be eaten raw. The remainder of the genus possesses poisonous and/or inedible seeds, such as M. whelanii and M. ternifolia; the toxicity is due to the presence of cyanogenic glycosides. These glycosides can be removed by prolonged leaching, a practice used by some Indigenous Australian people for these species, as well.
The two species of edible macadamia readily hybridize, and M. tetraphylla is threatened in the wild due to this. The seed was first described by Europeans south of Brisbane in 1828 by the explorer and botanist Alan Cunningham. One of the locations where wild macadamia trees were originally found was at Mount Bauple near Maryborough in southeast Queensland, Australia. Macadamia nuts are one of the few Australian endemic plant foods produced and exported in the quantities of a commodity.
The Hawaiian-produced macadamia established the well-known seed internationally. However, in 2006, macadamia production began to fall in Hawaii, due to lower prices from an over-supply.
Outside of Hawaii and Australia, macadamia is also commercially produced in South Africa, Brazil, California, Costa Rica, Israel, Kenya, Bolivia, New Zealand, Colombia, Guatemala and Malawi. Australia is now the world's largest commercial producer – accounting for roughly 40 percent of the approximately 100,000 tonnes of seeds in shell per year produced globally. To date, efforts to grow the macadamia commercially in Florida have not met with success, primarily as a result of low yield. However, the macadamia is a popular dooryard tree in Florida and efforts to select cultivars with better productivity are ongoing.
Macadamia nuts have sweet taste and are rich source of energy. 100 g of nuts provide about 718 calorie/100 g, which is one of the highest values among nuts.
They are packed with numerous health-benefiting nutrients, minerals, antioxidants and vitamins that are essential for optimum health and wellness
100 g of macadamia provides 8.6 g or 23% of daily-recommended levels of dietary fiber. Additionally, they are a very good source of phytosterols such as ß-sitosterol. However, the nuts contain no cholesterol.
Since macadamia is free from gluten, it is one of the popular ingredients in the preparation of gluten-free food formulas. Such formula preparations are a healthy alternative in patients with wheat gluten allergy and celiac disease.
The nuts are rich source of mono-unsaturated fatty (MUF) like oleic acid (18:1) and palmitoleic acids (16:1). Studies suggest that MUF fats in the diet help lower total as well as LDL (bad) cholesterol and increase HDL (good) cholesterol levels in the blood. The Mediterranean diet, which is rich in fiber, MUF fats and antioxidants work favorably in maintaining healthy blood lipid profile and thus offer protection from coronary artery disease and strokes.
Macadamias are an excellent source of minerals such as calcium, iron, magnesium, manganese and zinc. 100 g nuts provide 3.6 µg of selenium. Selenium is a cardio-protective micro-mineral and an important anti-oxidant cofactor for glutathione peroxidase enzyme.
Furthermore, the nuts are also rich in many important B-complex vitamins that are vital for metabolic functions. 100 g of nuts provide 15% of niacin, 21% of pyridoxine (vitamin B-6), 100% of thiamin, and 12% of riboflavin.
They contain small amounts of vitamin-A, and vitamin E. Both these fat-soluble vitamins possess potent anti-oxidant activities, which serve to protect cell membranes and DNA damage from harmful oxygen-free radicals.
In concise, sweet, refreshing macadamias are brimming with essential minerals, vitamins and heart-friendly mono-unsaturated fatty acids.
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