“You can purchase macadamia nuts flavored with onion, garlic, chili pepper, chocolate…and even SPAM.”
Some culinary nuts are often bought in the shell: peanuts, walnuts, and pistachios all come to mind. But what about the ones that you never see in the shell? Ever think about those?
One nut you have likely never seen in the shell is the macadamia, and for good reason. Unlike opening a peanut or a pistachio, it takes some serious muscle to extract the edible nut from its shell: 300 pounds of pressure per square inch to be exact, making it the hardest nut in the world to crack!
Some may think “Why bother?” We’ve got plenty of other nuts around.
Are macadamia nuts really worth the extra effort? Ask anyone from Hawaii, the world leader in macadamia nut production, and the question would most likely be an unequivocal yes!
The first macadamia tree came from Australia to Hawaii in 1881, and the first macadamia plantations were established about 40 years after that. In 1922 the University of Hawaii began a 20-year study of macadamia trees and eventually developed nine cultivars that consistently produce high-quality nuts.
Macadamia nuts are up to 80% oil, which accounts for their rich, buttery flavor. This also leads to a very high caloric content, which is perhaps tempered by the fact that the nuts are high in monounsaturated fats.
Their subtle sweetness comes through especially well when they’re roasted and salted. Because macadamia nuts grow exclusively in hot, sunny locations, many people think of them as an iconic “tropical” flavor. Eating a dessert that pairs macadamia with lemon, coffee or coconut can be like an island vacation for your palate.
While some prefer their macadamia nuts seasoned only with a touch of salt, macadamias are available in a wide array of fun and unusual seasonings. Through companies like Mauna Loa and Hamakua, you can purchase macadamia nuts flavored with onion, garlic, chili pepper, chocolate, mustard, coconut, jalapeno, coffee, teriyaki, wasabi, and even SPAM.
Do you go nuts for macadamias? Ever visit a plantation when on vacation in Hawaii? Got any good mac-centric recipes?
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Hands up if you know what an unripe macadamia looks like
Bauple nuts, Queensland nuts, Mullumbimby nuts, Bush nuts, Maroochi nuts, kindal kindal or boomberaare. All names for our native nut, the macadamia – which is not only delicious, but beautiful.
If you’ve only ever seen macadamias when ripe – or hidden in their thick, hard-to-crack shells – you’re missing out.
Perhaps you have only ever seen them standing in a packet on a supermarket shelf or in the bulk bin at your local health food shop, bright creamy white and nearly perfectly round? Well when on the tree they are triple the size and the nuts themselves covered in their vibrant green husk before they are picked. This is removed after harvesting and they are left in the shell to dry, before being cracked open to leave raw or roast and flavour with salt or spice.
Grown on green-leafed trees that can stretch to 25m tall, the nuts are Australia’s leading commercially grown native crop. It’s those straight from the tree macadamias that Hugh Fearnley-Whittingstall gathers up in the very first episode of River Cottage Australia, when he travels to the New South Wales south coast to meet would-be farmer Paul West.
Another thing that makes macadamias stand out is their status status among nuts as one of the fattiest of them all. Normally the words ‘high in fat’ and ‘high in calories’ would never be followed by ‘good for you’. But it’s the case with the macadamia.
And it’s the fat in the macadamia that makes them healthy – and increasingly popular around the world. Australia is the world’s leading producer of macadamia nuts. We export 70 per cent of our crop of approximately 40,000 tonnes, to more than 40 countries per year.
It’s the level of monounsaturated fat that makes macadamias stand out. Consumption of this particular fat has been proven to lower the rate of coronary heart disease, by decreasing the levels of LDL-cholesterol and by influencing other cardiovascular risk factors. Macadamias also contain protein, fibre, plant sterols and a range of vitamins and minerals.
Admittedly, macadamias aren’t cheap – often up to $45 per kilogram for shelled nuts. But there are many factors that contribute to the cost. For starters, it takes five to twelve years for a tree to produce any nuts – patience is still a must for those growing them.
Julian Mateer must have oodles of it. He has been growing macadamias for several years since he moved to his farm in the Byron Hinterland (perfect growing conditions for the macadamia). His farm is organic and a recent bout of nut rot has pushed his levels of patience further,
But, he says, it’s “Just one of the many daily hurdles of being a farmer in general.”
When it comes to macadamias, one of his biggest challenges is the cracking of the nut itself. Those nut crackers every grandpa in Australia seems to have on his lounge room side table in among the bowl of walnuts won’t do the job with macadamias, and while a hammer suffice for those of us cracking into a batch of macadamias at home, a producer needs expensive machinery to get the job done.
So why grow them? “Well that’s simple, for starters they taste absolutely delicious, addictive almost, and they look beautiful growing in the orchard, a vibrant green colour pre-harvest, plus they are so good for us.”
“That and the fact that they are the only native food found on the land – not the sea – that people actually eat and recognise without question in Australia”. Kangaroo, of course, is widely recognised, but not so widely consumed.
But it hasn’t always been the case.
Australia nearly lost a thriving industry and the name itself to overseas competition in the 1890s when nuts were taken from Queensland to Hawaii and a successful industry flourished on the American island. Back then the nuts were largely ignored by many Australians, but not by Indigenous Australians.
The nut’s scientific name (there are four specis of macadamias – Macadamia integrifolia and Macadamia tetraphyllaare the two that are commercially grown – refers to John Macadam, who worked with botanist Ferdinand von Mueller, who first described them for science in 1857. However, our first Australians ate them for thousands of years and knew them, among other names, as kindal kindal, gyndl, jindilli and boombera. They were not a staple as they are today in some diets, in fact they were considered a delicacy and were cherished and collected wherever they were found (which was mainly in their native north eastern New South Wales and central and south eastern Queensland) and they were also traded between tribes and used as special ceremonial gifts at inter-tribal corroborees. Eaten as a nut, made into flour or pressed into oil for medicinal purposes, the macadamia had multiple uses. Stones with special indentations were used to crack open the nuts.
Go nuts: macadamias top to this cherry and macadamia cake.
Today, Australia has more than 850 Aussie macadamia growers. It’s driven by our growing appetite for the creamy tree nut, along with growing interest in the Asia Pacific – Japan is our biggest overseas consumer, with interest growing in countries including Taiwan and Korea.
Macadamia and farm images by Rebecca Sullivan.
cracking good Charred carrot salad with sorrel, macadamia and herb vinaigrette
Chargrilling carrots this way releases their natural sweetness. Once tossed with the nuts and dates in the zingy mustard dressing, it is sure to become your go-to side.
Superfood granola with homemade almond-macadamia milk
This superfood granola incorporates a large amount of nuts, seeds and grains that have high nutritional integrity.
Sweet-and-salty toffeed macadamias
1. Let nuts fall naturally.
(a) Rake from under trees, pick up and separate from leaves. Pick up at least once a week.
(b) Remove husks. A large pair of pliers works well.
(c) Spread the husked nuts in a shallow screen-bottom tray in a dry place protected from the sun for two or three weeks.
2. Dry nuts further until shells are dry and brittle or nuts are loose in the shell and approach crispness. This can be done as follows:
(a) Place in a screen-bottom container over furnace register for 72 hours or more depending on nuts and amount of heat.
(b) OR – Place in a shallow pan in the oven at lowest temp. (about 100-115°). Stir occasionally and watch that you don’t cook the nuts. The warm setting on an electric oven is about right. Time required is usually about 12 hours.
3. Store nuts in a cool place until needed. A heavy plastic bag will prevent nuts from absorbing moisture.
OR – Crack and store nutmeats in a tightly covered container in refrigerator or freezer.
TO HOME ROAST MACADAMIA NUTS
Nuts thoroughly dried according to the above methods are tasty and ready to eat, but some people prefer them lightly roasted as follows:
1. Use nuts which have been thoroughly dried.
2. Pre-heat oven to 250°.
3. Place nut meats in a shallow pan, no more than two-deep, preferably a pan with screen-bottom tray to assure good air circulation.
4. DO NOT ROAST SMALLER WITH HALVES AND WHOLE NUTS AS THEY WILL SCORCH. Sort nuts and pieces into similar sizes and process each size separately.
ROAST NUTS 40-50 minutes, stirring occasionally. Remove from oven as soon as they start to tan, as the browning process continues after removal from the oven.
As there are variations in nuts, oven temperature regulators etc., it is best to watch closely and adjust time and temperature to meet your own conditions and tastes.
5. Remove from heat, add a dab of butter or neutral flavor oil and sprinkle with salt. Serve hot.
OR COOL and store in a tightly sealed jar in refrigerator or freezer.
Macadamias are a hard nut to crack, but that’s not the only step in the production of macadamia kernel.
The process starts on farm with growers harvesting the nuts, removing the fibrous outer husk and visually inspecting the nuts and removing any that are obviously defective. The nuts are then stored in a silo until a grower has a sufficient quantity ready to dispatch to MPC.
The nuts are received at MPC in a range of ways – from 400kg bins right up to B double loads of 35 tonnes. The weight delivered by a grower is recorded and samples are taken that are used to assess the mositure content and the quality of the nuts delivered. This information is used to determine how much a grower is paid for their consignment.
After sampling, the nuts are transferred via series of conveyors to a state of the art drying facility. This brand new drying facility utilises the latest in energy saving technology. The heat used for drying comes from the burning of macadamia shell – a by-product in the processing operation. The drying facility uses a recirculation system and when the air is too wet for drying, special fans exhaust this wet air from the building. At the same time, new drier air is brought into the drying facility from a specially designed roof area that is pre-heated by the sun.
The drying system is not only good for macadamia kernel quality but also the environment. By burning macadamia shell for drying, a renewable fuel source, MPC has been able to reduce its carbon emissions for drying by 99.6%
To avoid damage to the nuts when filling the large drying bins, a specially designed easy let down system is used. All of the drying steps are controlled by a computer system, allowing precise regulation of the temperature and humidity of the drying system.
After drying, the nuts are cracked. A purpose built machine breaks open the hard macadamia shell, revealing the creamy white kernel inside. A series of processes are used to separate the shell from the kernel – such as sizing graders, air separators (called aspirators) and electronic colour sorters. At the end of the process, macadamia kernel free from shell is then sent for manual inspection.
The first stage of sorting utilises state of the art electronic colour sorters. The machine is programmed to remove unsound kernel and/or shell by measuring colour intensities. These machines are fast! The colour sorter works like this:
During machine set-up, trained operators take pictures of good and bad kernels using the 2 cameras in the machine (one top and one bottom). The operator then uses the inbuilt software to identify the colour of the defect and the size of the colour area the defect covers. Each pixel is 0.1mm2 and the sorters can differentiate 16 million colours!
In operation, the macadamia kernel passes between the cameras where it is photographed, the computer scans the image of each kernel checking for bad colours and the area that the bad colour covers – with defective kernels being rejected by firing a short sharp burst of compressed air, which deflects the product into the reject stream. All of this happens in 4.3 milliseconds!
A Colour Sorter in operation
The kernel that passes through the colour sorter goes to the sorting area for manual inspection. The product that the colour sorter rejects is collected under the colour sorter and is further processed to recover saleable kernel. Reject kernel is not wasted – it is sent off and used for macadamia oil production.
The manual inspection area is where specially trained sorting staff inspect the kernel a final time to remove any defects missed at the other steps. From here the kernel moves to a sizing tower – this is where the kernel is separated into its different sizes (better known as styles) – these being whole kernels, halves and pieces.
Final manual sorting of macadamia kernel
Once sorted and sized, the kernel is tested to ensure it meets the highest standards. If the kernel does not meet the standard, it is resorted. Kernel that passes the rigorous testing process proceeds to pasteurisation where it is treated to ensure food safety. The pasteurisation process has been validated to provide 5 log reduction of food pathogens like Salmonella. After pasteurisation the kernel is packaged. Here a special machine dispenses an exact amount of kernel into cartons. The cartons are checked for weight and proceed along a conveyor system, where they have two identifying barcode labels attached – these labels identify the product and provide full traceability back to the farm.
All finished product is packed in vacuum sealed-nitrogen flushed foil pouches within cardboard cartons – this ensures the kernel stays as fresh as the day it was produced. From packing the cartons are stored in a warehouse – that operates at approximately 12 degrees celcius. A cool temperature is used to ensure the freshness of the kernel is maintained. From the warehouse kernel is dispatched to customers – both locally and all over the world, to make the finest macadamia products possible.
High quality packaging systems and state of the art cold storage is used to ensure the best quality and logest shelf life of kernel
The macadamia nut tree is a fast-growing, medium-sized evergreen tree with heavy, dark green foliage that hails from Australia. Its leaves – which are blunt tipped, oblong, and generally a foot or more longer – develop in either whorls of twos, threes, or fours, but are rarely solitary. Macadamia flowers are small and whitish, hassled and growing on long spikes, while its nuts can ripen throughout the year, though they primarily ripen in the fall and the spring. The nut has a leathery case that is 1 inch in diameter, containing either a spherical nut or two hemisphere nuts. They also have a smooth hard shell that encases a white kernel.
While macadamia nuts originate and are grown in Australia, commercial production is mainly in Hawaii. Some countries in Latin America, Africa, and Asia also grow macadamia nuts, while trees can be found in California and Florida for the continental United States.
The highest quality macadamia kernels are not only free of defects or insect and fungal damage, but also contain at least 72 percent oil. The kernels with less than 72 percent oil are usually immature and harder and will over-brown when roasted.
In Hawaii, commercial macadamia nut orchards are planted with grafted seedlings. Generally, the trees are at their most vulnerable during the first four years after tree establishment, after which the rows can grow together for a continuous canopy that makes the trees less prone to damage. After that, trees are likely to bear a small crop in the fifth year after planting and will reach full production in 12 to 15 years. A good tree can produce macadamia nuts for 40 years.
They prefer deep, well-drained soils that have a pH of 5.0 to 6.5, and require 60 to 120 inches of rainfall per year. They can be grown from sea level to an elevation of 2,500 feet. Macadamia trees have lower nut yields than other nut trees, meaning that it can take a while to start and maintain a positive cash flow. Because of this and harvesting expenses, macadamia orchards generally require a major capital investment.
The trees prefer subtropical climates, though too much humidity can increase the risk of blossom blights. Temperatures should not fall below -1 degree Celsius or regularly rise above 35 degrees Celsius, since the low temperatures increase the risk of damage while the high temperatures reduce vegetative growth, increases premature nut drop, decreases nut growth and oil accumulation, and may cause leaf burn.
Since they have only limited heat, frost, wind, drought, fire, and poor drainage resistance, finding a farm block of workable size for the macadamia trees can be difficult. In addition, blocks that have steep (more than 15 percent incline) or broken terrain will be more expensive to produce and manage, while blocks in drier areas (less than 1200 millimeters/47.25 inches of annual rainfall) will require irrigation. Strong wind is also a major concern for macadamia nut trees, because it can cause severe tree loss. However, narrow profile cultivars such as Kau and Pahala are more wind resistant than others.
Macadamia trees need a lot of management for profit and good nut quality. Because they are susceptible to many pests and diseases, they require regular monitoring and control measure applications. Orchard operations are also required to minimize environmental risk, due to increasing scrutiny, which means that issues such as noise pollution from de-husking, spray drift control, and soil erosion from high rainfall, shade, and mechanical harvesting need to be addressed.
Macadamia yields vary with location, season, variety, and management level. A well-managed orchard with tree spacings of 8 meters by 4 meters (or 312 trees per hectare) is expected to yield a peak of 3.5 to 4 tons of in-shell nuts per ha (12 to 13 kilograms per tree) at maturity, though poorly managed orchards or those on poor sites may not reach these figures.
Interplanting two cultivars of macadamia, such as cultivars 344 and 660, helps to improve yield through cross-pollination. Intercropping macadamia nuts with more quickly bearing crops is also a way to generate early returns. For example, in the Kona district on the big island of Hawaii, coffee is sometimes grown between macadamia nut trees.
Fertilization needs can be determined by semiannual leaf tissue analysis if it is possible. If the orchard appears normal, one sample collected before new leaf growth (February or March) or before fertilization (September or October) per tree should be enough. The branches for leaf tissue analysis should have a bud at the tip that is just opening and beginning to grow. They should not be branches with false flush buds, which have long, hard red scales and will not open for months.
Fifteen leaves from four to five trees are needed for each sample for analysis. The samples should be placed in plastic bags and labeled with name, date of sampling, and sample number.
Poorer land in Hawaii yields around 5,200 pounds per acre, while better land can yield at least 7,000 pounds per acre. In Australia, good orchards will yield around 4,000 to 5,000 pounds per acre.
Diseases that affect macadamia trees include macadamia root rot (Kretzschmaria clavis) and truck canker (Phytophthora cinnamomi). Dieback or slow decline can occur when there is trunk or root rot, soil compaction or poor drainage, poor root structure from planting root bound trees, toxic chemicals from herbicide or improper fertilizer application, or nutritional problems.
Macadamia quick decline (MQD) can also occur. While the stress factors for MQD are unknown stressors such as waterlogged soil, low pH, nutritional problems, ambrosia beetle attacks, and fungal/stem rots are suspected to be factors. Xylaria and Nectria fungi are frequently associated with MQD.
Flower blights can be caused by Phytophtora capsici or Botrytis cinerea, with Cladosporium usually as a secondary problem affecting raceme tips. While most premature nut drop is normal, environmental stress may cause excessive premature drop.
In addition to providing the nuts for harvest, macadamia trees can also help to generate honey production for nearby beehives. Sheep also can be used as natural lawn mowers to reduce the costs of herbicides and weeding, decreasing the risk of chemical toxicity in the soil and providing additional income with wool products.
Macadamia nuts are harvested manually after falling, which occurs for eight to nine months of the year in Hawaii (July to March). On relatively even land, large-scale producers use mechanical sweepers and pickup devices to offset the high cost of agricultural labor. CTAHR has developed a tractor-mounted pickup device that works for smaller orchards. To prevent losses from mold, germination, and animal damage, macadamia nuts should be harvested at least every four weeks during rainy weather, though they don’t need to be harvested as frequently during dry weather.
Unhusked nuts should not be stored for more than a day. Rather, it is best to husk the nuts immediately and either air dry them or take them to the processor the next day. In cases where the nuts were picked and cannot be husked or deliver to the processor, the in-husk nuts should be dried, by spreading them on a wire or slotted rack that is out of the rain and in direct sunlight.
While the shell accounts for most of the macadamia nut’s weight, with Hawaii’s average kernel recovery rate being around 23.5 percent during 1989-1990, an improved cracking system, along with better shell-kernel separators and high kernel cultivars, could raise the recovery rate to 35 percent.
In 1988-1999, 49 million pounds of gross, wet, in-shell nuts were delivered to processors and 3.5 million pounds (7.1 percent of the gross) were culled. This was primarily because of mold and rot, immature nuts, stink bugs, germinating nuts, koi seed worm (Cryptophlebia illepida), and the macadamia shot hole borer (Hypothenemus obscurus)
Prices paid by processors vary depending on world market forces of supply and demand, as well as Australia’s exchange rate. From 1990 to 2003, prices for in-shell nuts with 33 percent sound kernel recovery, 3.5 percent unsound kernel recovery max, and 10 percent moisture content ranged from $1.60 to $3.20 per kilogram.
Cost of Production
Before macadamia trees start to bear fruit, it can cost around $3,000 to $3,500 per hectare per year to operate a 312 tree per hectare orchard, making each tree around $10 to $12. This includes fertilization, irrigation, mulching, pest/disease/weed control, tree training, machinery operation, and labor costs. With harvesting, mechanical harvesting, de-husking, drying, and storing costs are generally around $1,000 to $1,500 per hectare, if there is a yield of 3,500 kilograms in-shell nuts per hectare. As a result, annual production costs for a mature orchard are around $4000-5000.
Significant income shouldn’t be expected until the sixth year, when the trees are mature and costs generally exceed income until the eighth year. Accumulated costs generally exceed accumulated income until at least the eleventh year. At an in-shell nut price of $2.50 per kilogram, a yield of 3,500 kilogram in-shell nuts per hectare, and production costs of $4,500 per hectare, the income from mature trees should be around $4,000 to $4,500 per hectare before fixed or overhead costs are subtracted. This makes a mature, 20-hectare orchard’s income roughly $80,000 to $90,000 before fixed or overhead costs are subtracted, though these figures can vary and taxation will affect the breakeven point.
There are no regulations or restrictions in the market of macadamia nuts, so the prices are determined by supply and demand market forces. The largest markets for macadamia nuts exported from South Africa are the United States, Europe, and Asia.
Currently, macadamia nuts are used for confectionary, baking, ice cream, and snack food industries. Because of the oil’s rich, cushiony skin feel and high oxidative stability, it is also suitable for heavy creams and skin care formulas. Research has shown that macadamia nut consumption may significantly lower heart disease risk.
The kernel, which is the main product of the macadamia nut tree, is oil or dry roasted after the husk is removed. Oil that is extracted from the culled nuts is commonly used in soaps, sunscreens, and shampoos, while the remaining press cake can be used in animal feed. An ounce of oil-roasted macadamia nut, which is about 10 to 12 whole kernels, has 204 calories, 21.73 grams fat, 2.06 grams protein, and 3.66 grams carbohydrates, along with 13 milligrams calcium, 33 milligrams magnesium, 57 milligrams of phosphorus, 94 milligrams of potassium, and 2 milligrams of sodium.
While the kernel and oil are the main products of macadamia nuts, both the shells and the husks also have uses. Macadamia shells can be used as mulch, as fuel in macadamia nut processing, as a planting medium for anthurium cultures (flowering plants native to tropical America), for plastic manufacture, or as a sand substitute for sandblasting. Macadamia husks can be used as mulch or compost for fertilizer.
Macadamia Crop Information
Links Checked October 2017.
How do I grow Macadamias?
Why not plant an edible Australian? The macadamia nut is arguably our finest contribution to the culinary world and it will grow particularly well in coastal gardens from Sydney to Queensland. It will also grow in all but the harshest of cooler climates if protected from frost in the first few years.
It is actually a member of the Proteaceae family (this includes waratahs, banksias and grevilleas), which means it should only be fertilised with low phosphorus feeds designed for native plants.
Under ideal conditions it will grow to a height of perhaps fifteen metres but less in cooler climates. As well as the delicious nuts it is also a rather ornamental plant as well,with interesting foliage and sprays of small but abundant white or pink flowers in spring. It can be somewhat messy once the flowers drop due to their abundance, so make allowances for this.
It makes a useful shade tree, with the bonus of being able to harvest your own crop of macadamia nuts. There are more dwarf varieties available for smaller gardens too, but always be aware that trees can have root systems that can cause issues with drains and sewers. If in doubt, there are root barrier systems that can be used to block the progress of ranging roots.
There are two varieties of Macadamia, M. tetraphylla with pale pink flowers, and M. integrifolia with cream flowers. Macadamia tetraphylla will take cooler weather, so is a better variety for southern states.
Seedling grown trees will bear nuts after around 10 years, but more reliable results come from grafted or cutting grown trees. The nuts take around 6 months to mature, and will fall to the ground when ripe where they can be collected. The nut is encased in a green outer husk which is removed and discarded. The nut should then be dried until the shell is hard, which will help with cracking the nut. This can take up to a month or two to do naturally.