.jpg)
Macadamia is a genus of four species of trees in the flowering plant family Proteaceae. They are indigenous to Australia, native to northeastern New South Wales and central and southeastern Queensland specifically. Two species of the genus are commercially important for their fruit, the macadamia nut /ˌmækəˈdeɪmiə/ (or simply macadamia). Global production in 2015 was 160,000 tonnes (180,000 short tons).[3] Other names include Queensland nut, bush nut, maroochi nut, bauple nut and, in the US, they are also known as Hawaii nut.[4] It was an important source of bushfood for the Aboriginal peoples.
.jpg)
.jpg)
The nut was first commercially produced on a wide scale in Hawaii, where Australian seeds were introduced in the 1880s, and for more than a century they were the world's largest producer.[5][6] South Africa has been the world's largest producer of the macadamia since the 2010s.
The macadamia is the only widely grown food plant that is native to Australia.
Description
Macadamia is an evergreen genus that grows 2–12 m (7–40 ft) tall.
The leaves are arranged in whorls of three to six, lanceolate to obovate or elliptic in shape, 60–300 mm (21⁄2–12 in) long and 30–130 mm (11⁄8–51⁄8 in) broad, with an entire or spiny-serrated margin. The flowers are produced in a long, slender, and simple raceme 50–300 mm (2–12 in) long, the individual flowers 10–15 mm (3⁄8–9⁄16 in) long, white to pink or purple, with four tepals. The fruit is a hard, woody, globose follicle with a pointed apex containing one or two seeds. The nutshell ("coat") is particularly tough and requires around 2000 N to crack. The shell material is five times harder than hazelnut shells and has mechanical properties similar to aluminum. It has a Vickers hardness of 35.[8][9]
Taxonomy
Species
| Image | Scientific Name | Distribution |
|---|---|---|
 | Macadamia integrifolia Maiden & Betche | south east Queensland and northern New South Wales |
 | Macadamia jansenii C.L.Gross & P.H.Weston | Queensland |
 | Macadamia ternifolia F.Muell. | Queensland |
.jpg) | Macadamia tetraphylla L.A.S.Johnson | Queensland |
Nuts from M. jansenii and M. ternifolia contain cyanogenic glycosides.[10][11] The other two species are cultivated for the commercial production of macadamia nuts for human consumption.
Previously, more species with disjunct distributions were named as members of this genus Macadamia.[2] Genetics and morphological studies published in 2008 show they have separated from the genus Macadamia, correlating less closely than thought from earlier morphological studies.[2] The species previously named in the genus Macadamia may still be referred to overall by the descriptive, non-scientific name of macadamia.
Etymology
The German-Australian botanist Ferdinand von Mueller gave the genus the name Macadamia in 1857 in honour of the Scottish-Australian chemist, medical teacher, and politician John Macadam, who was the honorary Secretary of the Philosophical Institute of Victoria beginning in 1857.[15]
Cultivation
The macadamia tree is usually propagated by grafting and does not begin to produce commercial quantities of seeds until it is 7–10 years old, but once established, it may continue bearing for over 100 years. Macadamias prefer fertile, well-drained soils, a rainfall of 1,000–2,000 mm (40–80 in), and temperatures not falling below 10 °C (50 °F) (although once established, they can withstand light frosts), with an optimum temperature of 25 °C (80 °F). The roots are shallow, and trees can be blown down in storms; like most Proteaceae, they are also susceptible to Phytophthora root disease. As of 2019, the macadamia nut is the most expensive nut in the world, which is attributed to the slow harvesting process.[16]
Cultivars
Beaumont
A Macadamia integrifolia / M. tetraphylla hybrid commercial variety is widely planted in Australia and New Zealand; Dr. J. H. Beaumont discovered it. It is high in oil but is not sweet. New leaves are reddish, and flowers are bright pink, borne on long racemes. It is one of the quickest varieties to come into bearing once planted in the garden, usually carrying a useful crop by the fourth year and improving from then on. It crops prodigiously when well pollinated. The impressive, grape-like clusters are sometimes so heavy they break the branchlets to which they are attached. Commercial orchards have reached 18 kg (40 lb) per tree by eight years old. On the downside, the macadamias do not drop from the tree when ripe, and the leaves are a bit prickly when one reaches into the tree's interior during harvest. Its shell is easier to open than that of most commercial varieties.
Maroochy
A pure M. tetraphylla variety from Australia, this strain is cultivated for its productive crop yield, flavour, and suitability for pollinating 'Beaumont.'
Nelmac II
A South African M. integrifolia / M. tetraphylla hybrid cultivar, it has a sweet seed, which means it has to be cooked carefully so that the sugars do not caramelise. The sweet seed is usually not fully processed, as it generally does not taste as good, but many people enjoy eating it uncooked. It has an open micropyle (hole in the shell), which may let in fungal spores. The crack-out percentage (ratio of nut meat to the whole nut by weight) is high. Ten-year-old trees average 22 kg (50 lb) per tree. It is a popular variety because of its pollination of 'Beaumont,' and the yields are almost comparable.
Renown
A M. integrifolia / M. tetraphylla hybrid, this is a rather spreading tree. On the plus side, it is high yielding commercially; 17 kg (37 lb) from a 9-year-old tree has been recorded, and the nuts drop to the ground. However, they are thick-shelled, with not much flavour.
Production
In 2018, South Africa was estimated as the leading producer of macadamia nuts, with 54,000 tonnes out of global production of 211,000 tonnes.[17] Macadamia is commercially produced in many countries of Southeast Asia, South America, Australia, and North America having Mediterranean, temperate or tropical climates.[17]
History
The first commercial orchard of macadamia trees was planted in the early 1880s by Rous Mill, 12 km (7.5 mi) southeast of Lismore, New South Wales, consisting of M. tetraphylla.[18] Besides the development of a small boutique industry in Australia during the late 19th and early 20th centuries, macadamia was extensively planted as a commercial crop in Hawaii from the 1920s onward. Macadamia seeds were first imported into Hawaii in 1882 by William H. Purvis, who planted seeds that year at Kapulena.[19] The Hawaiian-produced macadamia established the well-known seed internationally, and in 2017, Hawaii produced over 22,000 tonnes.[20]
In 2019, researchers collected samples from hundreds of trees in Queensland and compared their genetic profiles to samples from Hawaiian orchards. They determined that essentially all the Hawaiian trees must have descended from a small population of Australian trees from Gympie, possibly just a single tree.[21] This lack of genetic diversity in the commercial crop puts it at risk of succumbing to pathogens (as has happened in the past to banana cultivars). Growers may seek to diversify the cultivated population by hybridizing with wild specimens.
Shelling
Macadamias are the world's hardest edible nut to crack.[22] Since ordinary nutcrackers apply insufficient force[23], various types of specialist macadamia nut crackers are available, many of which apply force to the micropyle (white dot) to fracture the shell.[22]
For commercial scale deshelling, rotating steel rollers are used.[23] In South Africa, the average crack-out rate, meaning ratio of usable nut to discarded shell, is 27.6% nut to 72.4% waste.[23]
Toxicity
Nuts from M. jansenii and M. ternifolia contain cyanogenic glycosides.
Allergen
Macadamia allergy is a type of food allergy to macadamia nuts which is relatively rare, affecting less than 5% of people with tree nut allergy in the United States.[24] Macadamia allergy can cause mild to severe allergic reactions, such as oral allergy syndrome, urticaria, angioedema, vomiting, abdominal pain, asthma, and anaphylaxis.[25] Macadamia allergy can also cross-react with other tree nuts or foods that have similar allergenic proteins, such as coconut, walnut, hazelnut, and cashew.[26] The diagnosis and management of macadamia allergy involves avoiding macadamia nuts and their derivatives, reading food labels carefully, carrying an epinephrine auto-injector in case of severe reactions, and consulting a doctor for further testing and advice.
Toxicity in dogs and cats
Macadamias are toxic to dogs. Ingestion may result in macadamia toxicity marked by weakness and hind limb paralysis with the inability to stand, occurring within 12 hours of ingestion.[27] It is not known what makes macadamia nuts toxic in dogs.[28] Depending on the quantity ingested and the size of the dog, symptoms may also include muscle tremors, joint pain, and severe abdominal pain. In high doses of toxin, opiate medication may be required for symptom relief until the toxic effects diminish, with full recovery usually within 24 to 48 hours.[27]
Macadamias are also toxic to cats, causing tremor, paralysis, stiffness in joints and high fever.[29]
| Nutritional value per 100 g (3.5 oz) | |||
|---|---|---|---|
| Energy | 3,080 kJ (740 kcal) | ||
13.8 g | |||
| Sugars | 4.57 g | ||
| Dietary fiber | 8.6 g | ||
75.8 g | |||
| Saturated | 12 g | ||
| Monounsaturated | 59 g | ||
| Polyunsaturated | 1.5 g | ||
7.9 g | |||
| |||
| Other constituents | Quantity | ||
| Water | 1.4 g | ||
| †Percentages estimated using US recommendations for adults,[30] except for potassium, which is estimated based on expert recommendation from the National Academies.[31] | |||
Uses
Nutrition
Raw macadamia nuts are 1% water, 14% carbohydrates, 76% fat, and 8% protein. A 100-gram reference amount of macadamia nuts provides 740 kilocalories and are a rich source (20% or more of the Daily Value (DV)) of numerous essential nutrients, including thiamine (104% DV), vitamin B6 (21% DV), other B vitamins, manganese (195% DV), iron (28% DV), magnesium (37% DV) and phosphorus (27% DV).
Compared with other common edible nuts, such as almonds and cashews, macadamias are high in total fat and relatively low in protein. They have a high amount of monounsaturated fats (59% of total content) and contain, as 17% of total fat, the monounsaturated fat, omega-7 palmitoleic acid.[32]
Other uses
The trees are also grown as ornamental plants in subtropical regions for their glossy foliage and attractive flowers. The flowers produce a well-regarded honey. The wood is used decoratively for small items.[33] Macadamia species are used as food plants by the larvae of some Lepidoptera species, including Batrachedra arenosella.[citation needed]
Macadamia seeds are often fed to hyacinth macaws in captivity. These large parrots are one of the few animals, aside from humans, capable of cracking the shell and removing the seed
Macadamia nuts are rich in vitamins, minerals, fiber, and antioxidants. Their benefits may include weight loss, improved gut health, and protection against conditions like diabetes or heart disease.
Macadamia nuts are tree nuts that have a subtle, butter-like flavor and creamy texture.
Native to Australia, macadamia trees are now grown in various places around the world, such as Brazil, Costa Rica, Hawaii, and New Zealand.
Like most other nuts, macadamia nuts are rich in nutrients and beneficial plant compounds. They’re also linked to several benefits, including improved digestion, heart health, weight management, and blood sugar control.
Here are 10 health and nutrition benefits of macadamia nuts.
Macadamia nuts are calorie-rich nuts that are high in healthy fats, vitamins, and minerals. One ounce (28 grams) offers (
- Calories: 204
- Fat: 23 grams
- Protein: 2 grams
- Carbs: 4 grams
- Sugar: 1 gram
- Fiber: 3 grams
- Manganese: 58% of the Daily
Value (DV) - Thiamine: 22% of the DV
- Copper: 11% of the DV
- Magnesium: 9% of the DV
- Iron: 6% of the DV
- Vitamin B6: 5% of the DV
Macadamia nuts are also rich in monounsaturated fats, a type of fat that may boost heart health by lowering your total and LDL (bad) cholesterol levels (
These nuts are low in carbs and sugar and have a moderate fiber content. This combination makes them unlikely to spike your blood sugar levels, which may be especially beneficial for people with diabetes (
Summary Macadamia nuts are rich in vitamins,
minerals, and fiber, yet low in carbs and sugar. What’s more, they boast healthy
monounsaturated fats.
Like most nuts, macadamia nuts are a great source of antioxidants.
Antioxidants neutralize free radicals, which are unstable molecules that can cause cellular damage and increase your risk of conditions like diabetes, Alzheimer’s disease, and heart disease (
Additionally, macadamia nuts boast some of the highest flavonoid levels of all tree nuts. This antioxidant fights inflammation and helps lower cholesterol (
Furthermore, this nut is rich in tocotrienols, a form of vitamin E with antioxidant properties that may help lower cholesterol levels. These compounds may even protect against cancer and brain diseases (
Summary Macadamia nuts are loaded with flavonoids and
tocotrienols, antioxidants that safeguard your body against cellular damage and
disease.
Macadamia nuts may lower your risk of heart disease.
Various studies suggest that eating 0.3–1.5 ounces (8–42 grams) of these nuts daily can lower total and LDL (bad) cholesterol levels by up to 10% (
Interestingly, a small study in people with high cholesterol noted that a diet rich in macadamia nuts reduced levels of this blood marker as much as a heart-healthy, low-fat diet recommended by the American Heart Association (
What’s more, eating 1.5–3 ounces (42–84 grams) of macadamia nuts each day may significantly reduce markers of inflammation, such as leukotriene B4. Inflammation is a risk factor for heart disease (
Researchers believe the heart benefits of macadamia nuts may come from their high monounsaturated fat content.
This fat is consistently linked to better heart health and a lower risk of stroke and fatal heart attacks (
Summary Macadamia nuts are rich
in heart-healthy monounsaturated fats. Eating small amounts each day may help
reduce heart disease risk factors, such as high cholesterol and inflammation.
Metabolic syndrome is a cluster of risk factors, including high blood sugar and cholesterol levels, that raise your risk of stroke, heart disease, and type 2 diabetes (
Research shows that macadamia nuts may protect against both metabolic syndrome and type 2 diabetes.
For instance, one recent review linked diets rich in tree nuts, including macadamia nuts, to reductions in fasting blood sugar levels.
The diets included in this review had people eat 1–3 ounces (28–84 grams) of tree nuts per day. They experienced significantly improved levels of hemoglobin A1c, a marker of long-term blood sugar control (
Furthermore, diets rich in monounsaturated fats — which comprise 80% of the fat in macadamia nuts — may help reduce risk factors for metabolic syndrome, especially in people with type 2 diabetes (
In general, nut intake is also linked to lower blood sugar and body weight in people with metabolic syndrome or type 2 diabetes (
Summary Regularly eating tree nuts, including
macadamia nuts, may reduce your risk of metabolic syndrome and contribute to
lower, more stable blood sugar levels.
Despite being rich in calories, macadamia nuts may help you lose weight.
This may be partly explained by their amounts of protein and fiber, two nutrients known to reduce hunger and promote feelings of fullness (
Research further shows that a portion of the fats in nuts may remain in the nut’s fibrous wall during digestion. Thus, macadamia and other nuts may provide fewer calories than previously thought (
In one 3-week study, 71 young Japanese women ate bread daily with either 10 grams of macadamia nuts, coconut, or butter. Those in the macadamia group lost 0.9 pounds (0.4 kg) by the end of the study, while those in the other groups remained at the same weight (
Macadamia nuts are also rich in monounsaturated fats, especially the omega-7 fat palmitoleic acid, which may protect against unwanted weight gain.
In one 12-week study, obese mice fed high-fat diets with large amounts of macadamia oil — rich in palmitoleic acid — had significantly smaller fat cells than those given none of this product (
However, it’s unclear whether macadamia nuts offer the same benefits in humans.
Summary Macadamia nuts may reduce hunger and promote
feelings of fullness, which can benefit weight loss. They may also provide
fewer calories than previously believed.
Macadamia nuts contain fiber, which can benefit your digestion and overall gut health.
As is the case with most nuts, the soluble fiber in macadamia nuts can act as a prebiotic, meaning that it helps feed your beneficial gut bacteria (
In turn, these friendly bacteria produce short-chain fatty acids (SCFAs), such as acetate, butyrate, and propionate, which can reduce inflammation and protect against conditions like irritable bowel syndrome (IBS), Crohn’s disease, and ulcerative colitis (
Summary The soluble fiber in macadamia nuts aids your
digestion by feeding your beneficial gut bacteria. In turn, this can improve
your gut health.
Emerging research suggests that macadamia nuts may offer a few additional health benefits, including (7,
- Providing anticancer properties. Macadamia nuts
contain flavonoids and tocotrienols, plant compounds that test-tube
studies indicate may help fight or kill cancer cells. However, more
research is needed. - Boosting brain health. Test-tube and
animal research shows that tocotrienols may also protect brain cells from conditions like
Alzheimer’s and Parkinson’s. Still, human research is needed. - Bumping up your
longevity.
Regular intake of nuts, including macadamia nuts, may help cut your risk
of dying prematurely by around one-third.
Keep in mind that these potential attributes are far from proven. More human studies are needed.
Summary Regularly eating macadamia nuts may reduce
your risk of dying prematurely and help protect against cancer and brain
diseases. It’s important to note that more research is needed before strong
conclusions can be made.
Macadamia nuts are found in most supermarkets but can also be ordered online. They’re versatile and easy to incorporate into most diets.
In general, raw macadamia nuts are the healthiest form. Dry-roasted ones provide a good alternative if you don’t have the time to roast them yourself, but try to stay away from oil-roasted versions, which contain unnecessary added fats.
You can snack on whole macadamia nuts, grind and sprinkle them onto soups and warm dishes, or swap them for croutons in salads.
Macadamia butter is another way to enjoy this nut. Like peanut butter, it can be spread on bread, crackers, and fruit slices, or added to oatmeal or yogurt.
Finally, these nuts can be soaked and ground into a paste to make dairy-free cheese or milk. This paste can also provide a base for various desserts.
Macadamia nuts can be stored at room temperature for one to five months, ideally in an airtight container. Storing them in your refrigerator will keep them fresh even longer — up to one year (38).
Summary Macadamia nuts are a versatile addition to
most diets. They can be eaten whole, ground, raw, roasted, or as a nut butter
and make for an interesting addition to main courses, snacks, and desserts.
Macadamia nuts are rich in vitamins, minerals, fiber, antioxidants, and healthy fats.
Their potential benefits include weight loss, improved gut health, and protection against diabetes, metabolic syndrome, and heart disease.
If you’re curious about this nut, try adding it to your diet today.
Comments
Post a Comment