The macadamia nut is native to certain areas of Australia. Locally it is known by many names, including bush nut, Queensland nut, maroochi nut and bauple nut. Globally it is more commonly known as macadamia.
There are only four species of macadamia, three of which are of commercial importance and only two of which are edible in raw form. The inedible species are poisonous, the toxicity in the fruit coming from cyanogenic glucosides. When chewed, the cyanogenic glucosides mix with the enzymes in your mouth and hydrogen cyanide is formed. Severe allergic reactions have been noted, including itchy throat, swelling of the lips or anaphylaxis. Those with tree nut allergies should be abundantly cautious. These nuts are extremely toxic to dogs – including the human-edible ones. One could expect muscle weakness, tremors, hind limb paralysis and joint pain if a pet were to get a hold of them.
Growth and Production
The fruit of the macadamia tree is very hard, woody and contains one or two seeds (nut). The tree can grow as large as North American evergreen trees, anywhere from two to 12 metres. The two edible species of seed are easy to hybridize; however, this is causing one of the seed species to become threatened in the wild. These trees are usually propagated by grafting, and they don’t typically begin to produce commercial quantities of product until it is seven to 10 years old, although once established, a macadamia tree can be expected to bear fruit for more than 100 years. The tree requires fertile and well-drained soil, up to 2,000 millimetres of rain per year and temperatures that stay above 10° Celcius – at least until the roots are established. The roots of the macadamia are shallow, and a strong wind can blow the trees down, while a particularly bad storm can decimate a crop.
The shell of a macadamia nut is very tough to crack. A metal vise or a heavy mallet is used to compress the shell until it lightly cracks, then the seed is repositioned so it can be fractured along another plane. It seems very labour-intensive! Before extracting the seed from the shell, the macadamia needs to be dried in-shell to reduce the moisture content and allow the nut to pull away from the inner lining of the shell.
Macadamia is one of the few Australian endemic plant foods produced and exported in the quantities to be considered a commodity. Australia and Hawaii were, until 2012, the highest-producing countries for the macadamia nut, with a combined output of 35.2 metric tonnes. South Africa recently surpassed them, with an overall production of 37 metric tonnes. Most of South America, Israel and Kenya also produce macadamia for export. Efforts to grow the macadamia commercially in the United States have so far failed, although you will find the trees commonly grown in gardens throughout Florida.
History and Usage
Macadamia nuts were an important part of life for the aborigines of Eastern Australia for thousands of years before European settlers arrived. The high fat content was highly coveted by the indigenous people, although the difficulty cracking the nuts may have exempted it as a staple food.
The seed of the macadamia was first described in 1828 by botanist Allan Cunningham. It wasn’t until the early 1880s that the first commercial orchard was planted, making the macadamia a relatively young commodity in comparison to other popular nuts.
Many processing stones have been found throughout the rainforests. These tools consisted of a large stone with an incision for holding the nuts and a smaller flat stone to sit on top. The flat stone was then struck by a “hammer” stone. Unfortunately, modern technology has not found a much better nutcracker than this, and essentially the same methods are still employed today.
Aboriginals ate the nuts raw or roasted them in the hot coals of the fire. They would express the oil from the seed and use it as a binder with ochres and clay for face and body paint. The nut oil was also used as a carrier for other plant extracts and used to treat ailments. It was believed the macadamia nut contained a stimulant which aided breast milk production. Today macadamia is still used as a carrier oil, although it’s expensive. It is also used in skincare products and cosmetics – its high oxidative stability (it doesn’t go quickly rancid) and the content of omega-7 palmitoleic acid makes it a great botanical alternative to mink oil. The macadamia has a buttery, earthy flavour and makes a great addition to any recipes calling for nuts. You can make your own macadamia butter or spread or eat the nuts roasted, but I prefer to eat them right out of the freezer. The crunchy smooth texture is heavenly!
There were at least 12 indigenous tribes where the trees grew wild and the nuts were used as an item of trade with other tribes. When the white settlers arrived, the tribesmen traded macadamia along with rum, tobacco and native honey.
In 1882 some seedlings were transported to Hawaii where they were planted and propagated until the 1920s arrived and the trees were extensively planted for commercial production. It was Hawaii’s macadamia production that established the seed as an international commodity.
Nutritionally speaking, macadamia have one of the highest fat contents of all the nuts on the market today. One hundred grams of macadamia contains 740 calories – 76% fat and only 8% protein. One will also find thiamin, vitamin B6, phosphorous, manganese, iron and magnesium in a serving of macadamia.