Macadamia nuts are as much as 76 percent oil by weight and 9.4 percent protein, along with various vitamins, minerals and antioxidants. Macadamia has no cholesterol or trans-fatty acids. Heart healthy, monounsaturated oleic acid is as much as 64 percent of macadamia nuts' total fatty acids, and omega-7 monounsaturated palmitoleic acid is as much as 15.6 percent. Palmitoleic acid is typically found in fish oils and is rare in plants.
Discovery
Macadamia integrifolia was collected from the Australian rain forest in 1857 by German pharmacist and botanist Ferdinand von Mueller, director of the Royal Botanical Gardens in Melbourne. Von Mueller encouraged commercialization of native Australian plants, including the first distilling and export of eucalyptus oil. Macadamia orchards were planted in Australia and Hawaii in the 1880s. In 1948, a commercial orchard was established at Keauhou in Hawaii, followed by commercial development in Australia in the 1960s.
New Oil in Africa
High oil content produces the crisp macadamia nut texture consumers prefer. Unshelled nuts are graded at three levels based on oil content determined by buoyancy in water. Grade 1 nuts contain 75 percent oil, but Grade 3 contains 45 to 65 percent. In early Hawaiian production, Grade 3 nuts were discarded and Grade 1 nuts were roasted in coconut oil before market. By the 1980s, African nations without coconut industries entered macadamia production. They pressed Grade 3 nut oil in which to roast Grade 1 nuts.
Oleic Acid
Nuts are low in saturated fatty acids that pose a risk of heart and artery disease and high in heart healthy monounsaturated and polyunsaturated fatty acids The abundance of the monounsaturated oleic acid makes macadamia nuts useful in dietary control of mildly high cholesterol levels. In 2007, biomedical researcher Manohar L. Garg of the University of Newcastle, Australia, observed that even in the short term, macadamia nuts favorably changed the markers of oxidative stress, thrombosis and inflammation associated with coronary disease.
Palmitoleic Acid
The Australian Commonwealth Scientific and Research Organization, or CSIRO, Division of Human Nutrition, reviewed palmitoleic acid’s cholesterol influence in 1994. Their researcher P. Nestel noted in the Journal of Lipid Research that isolated pure palmitoleic acid raised cholesterol levels in 34 males with existing high cholesterol, acting the same as a saturated fat. However, palmitoleic acid has exceptional potential in the cosmetics industry. Palmitoleic acid is present in abundance in the skin of children and declines significantly with age. Palmitoleic acid is lethal to gram-positive bacteria and has potential as a natural preservative in cosmetics.
Expensive Production
An orchard is a long-term investment. Hawaiian orchards pioneered cloning techniques in which macadamia cultivar cuttings are grafted onto seedling macadamia roots to create orchard stock that will yield economical returns in the seventh year after transplant to the orchard. In Australia, 150 species of pests attack macadamia, several of which can potentially destroy the annual crop.
References
- Lipids; Macadamia Nut … Modulates Risk Factors ... Coronary Artery Disease …; Manohar L. Garg, et al.; June 2007
- J of Lipid Res; Effects of … Dietary Palmitoleic Acid on … Hypercholesterolemic Men; P. Nestel et al.; 1994
- Chronica Horticulturae; Macadamia: Domestication and Commercialisation; Russ Stephenson; 2005
- “New Sources of Fats and Oils”; Macadamis as Edible Oil ... ; N. Macfarlane, R.V. Harris; 1981
- Gomal University J of Res; Evaluation of Basic Properties of Macadamia Nut Oil; Naveed Akhtar et al.; 2006
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