Macadamia nuts

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Macadamia Nuts


Macadamia intergrifolia

Macadamia tetraphylla




Queensland nut, Australian nut, bopple nut, bauple nut, popple nut, kindal kindal, boombera, burrawang (Aboriginal)


Macadamia is indigenous to coastal rainforests of South Queensland and the northern river districts of New South Wales, Australia (Cavaletto). It has since been introduced to many- other countries, particularly in Africa.

The trees cannot tolerate frost and are suited best to areas where there are alternate wet and dry seasons (Cavaletto).


HAWAII, AUSTRALIA, USA, Kenya, Guatemala, Costa Rica, Malawi, Zimbabwe, South Africa, Brazil, Fiji.

In 1978 Hawaii, for example, produced 9 500 tonnes of inshell nuts (Rosengarten).


Two species of the family produce edible nuts, M. tetraphylla known as rough shell macadamia and M. intergrifolia known as smooth shelled macadamia. The fully mature nut consists of a nearly round nut in hard spherical brown testa, or shell, about 25 mm in diameter and 2-3 mm thick which is in turn surrounded by a fibrous green pericarp some 2 to 4 mm thick. Normally only one nut develops in each fruit. The tree begins to bear fruit when it is about 6-7 years old and has a lifespan of approximately 60 years. Trees can yield between 27 - 68 kg of nuts per year (Cavaletto). Nuts have an oil content of 60% (Maefalane).


The kernels are mainly sold whole as high value edible nuts. Macfalane and Harris (NRI, 1981) show that reject kernels can be processed to yield an edible oil. The shell is used as a mulch or, if mixed with pineapple and molasses, for animal feed (Woodroof). It can also be used as a source of fuel. Some industrial units use the shell to fire their boilers. (calorific value 10,000 BTU/lbs) (Rosengarten). The oil extraction process produces an oilcake which is suitable as a feed for non ruminant animals (Macfalane). The hull powder is used as a filler in the plastics industry (Woodroof).




Macadamia trees are usually grown in plantations, especially in Hawaii where there has been extensive research into the crop.

Trees can be grown from seedlings but it is suggested that this type of planting yields low oil content as there are too many variations in productivity and kernel quality.

A preferred method of planting is by grafting trees of selected varieties. New grafting methods have reduced propagation from 2 years to 1 year and have also increased success from 66.8% - to 94.8% (Campo-Dall'Orto).


10 Spp of Macadamia have been identified, M. intergrifolia and tetraphylla are the only two that produce edible oil nuts. In Hawaii 9 selections of intergrifolia have been used for creating varieties. The rough shelled M. tetraphylla has less desirable processing characteristics than intergrifolia.

It is not really grown for commercial purposes. The varieties used are: (HAES 246) Keauhou, (HAES 333) Ikaika, (HAES 508) Kakea, (HAES 660) Kcaau, (HAES 344) Ka'u, (HAES 741) Mauka, (HAES 800) Makai, (HAES 294) Purvis, and (HAES 788) Pahala (Cavaletto).

Listed below is a summary of insect pests which attack Macadamia, taken from different sources.

Peoudotheraptus wayi

Maladera matrida

Monolepta australis

Cryptoblabes gnidiella larvae

Spectrobates ceratoniae

Crvtophlebia leucotreta

Nezara spp.

Erysichton lineata

Ulonemia spp.

Toxoptera aurantii

Amblypelta nitida

Cryptophlebia ombrodelta

Damage from rats can also be serious, cases have been noted where 50% of the crop has been lost as a result of rat infestation.

Major diseases noted: In Taiwan 1982, extensive root decay in macadamia was noted, caused by Ganoderma tucidum and Kretzschmania clavus (Ann). Phytophthora cinnamomi has been noted to cause trunk canker disease in Australia (Pegg).


About 215 days after flowering, the nuts mature and fall to the ground. Harvesting extends over a seven month period, therefore several harvests are required.

In general, harvesting in the northern hemisphere occurs between August and February while harvesting in the southern hemisphere takes place between March and September (Cavaletto). During the main harvest, nuts are gathered at intervals of 2 weeks. For the rest of the harvest period they are collected once a month (Woodroof).


Harvesting is usually by manual collection of the nuts from the ground. Picking is generally avoided as there is great difficulty in distinguishing between immature and mature fruits (Grimwood). In Hawaii, to provide a smooth surface for the nuts to fall upon, some areas are covered with volcanic cinders. Mechanical harvesting methods have been developed. For example, an inexpensive tractor mounted nut recovery attachment has been designed. Experiments show that it is 90% efficient and can replace 30 hand pickers (Paquin). Other methods use nets hung between trees to catch the falling nuts. This is not often used as the nets are expensive and are often contaminated with fallen leaves (Cavaletto).




The husks are removed and the nuts are dried within 24 hours of harvest. Failure to do so initiates undesirable physiological activity which causes fermentation and spoilage.

For the production of edible nuts it is important to dry the nuts from an initial moisture content of 45% to between 5% - 1.5%. This is done by passing air through the nuts for a week, followed by an application of low heat (38 deg C - 54 deg C), for an additional 7-10 days (Cavaletto). At a smaller scale nuts are placed 2-3 deep in trays which have good air circulation and these are left to dry for about 2-3 weeks (Rosengarten).

If stored in bulk, respiratory activity results in increased temperatures and creates high relative humidity. In such conditions lipolysis and moulds become storage problems. The nuts should be stored in a rainproof shelter or drying shed (Rosengerten).

Simple drying racks can be made from 1.27-0.635 cm meshed cloth stapled to a light wooden frame (Rosengarten).




A range of technical options exist for shelling, or decorticating, the nut". These range from simple hand methods, through to machines that apply pressure with a rotating rubber tyre (Cavaletto), to large commercial crackers. Walnut decorticators have teen used with some success in Hawaii, but are expensive (Woodroof). Other machines use counter rotating steel rollers. Experiments in Hawaii have been successful in showing that flame drying can be used to decrease the macadamia nutshell moisture below that of the kernel so causing it to become brittle and easy to crack (Tang).

After the nuts have been removed from their shells they are graded. Fresh nuts are placed into a saline bath of specific gravity 1.024.

If they float they are placed into a water bath. The nuts that rise to the surface are classed as grade I nuts and are packaged as "Top Quality Edible Nuts". Those that sink are classed as grade II nuts and are sold whole for edible purposes.

The nuts that sink during the first immersion are placed into another saline bath which has a specific gravity of 1.15. If they float they are graded as Grade III and are used for oil extraction. The debris, such as shells, usually sink at this stage.

Those nuts falling into Grade III can account for about 25% of the nuts processed (Macfalane).


Oil is extracted from reject grade III nuts using small expellers and finds use as cooking oil, and by the cosmetic industry. (Anon). It has been shown that it is necessary to add a proportion of fibre in the form of press cake to the feed of kernels to obtain good extraction rates (Macfalane). In Malawi the oil is made into soap.


Myristic acid 0.7%
Palmitic acid 9.1%
Palmitoleic acid 21.9%
Stearic acid 2.2%
Oleic acid 59.9%
Linoleic acid 1.9%
Arachidonic acid 1.8%
Eicosenoic acid 2.0%

(Source: Cavaletto)

A high oleic acid to low linoleic acid ratio suggests that the oil is quite stable to oxidative deterioration (Macfalane).

The oil extracted using expellers is pale yellow in colour and has a taste and smell similar to unprocessed macadamia nuts (Macfalane).


Decorticators, driers, Saline bath. An expeller with a throughput of about 25 kg/hr has been recommended for small scale production (Macfalane).

Additional information was unidentifiable for the following areas: AGRICULTURAL ASPECTS, planting period, major pests and diseases; PROCESSING AND OIL EXTRACTION, nomenclature of products.



ANON, "Macadamia Beauty Products", Chemist & Druggist, 1984, 221, No. 5402, p.87.

ANN, P.J. KO, W.H. "Root Rot of Macademia Caused by Ganoderma tucidum and Kretzschmania clavus in Taiwan", Journal of Agricultural Research China, 37, 4, pp. 424429, 1988.

CAMPO-DALL'ORTO, K.A. OJIMA, M. BARBOSA, W. SABINO, J. C. RIGITARIO, O. "Early Grafting of Macadamia Seedlings", Bragantia, Instituto Agronomico de Campinas Brazil, 45, 2, pp. 289-295, 1988.

CAVALETTO, C.G. "Macadamia Nuts", pp.542-559, "Tropical and Subtropical Fruits, Composition, Properties and Uses", Edited by NAGY, S. SHAW, P. E. AVI Publications Company, 1980.

CAVALETTO, C.G. "Handbook of Tropical Foods", pp.362-392, Edited by CHAN, H. T. Marcel Dekker Inc.

CROIX, E.A.S. la. "THINDWA, H.Z. "Macadamia Pests in Malawi. IV. Control of Bugs and Borers", Tropical Pest Management, 32, 2, 1986.

GOLBERG, A.M. YATHOM, S. ALMOGI-LABI, A. FRIDLAND-WUNDER, G. "Diurnal and Seasonal Occurrence, Feeding Habits and Mating Behaviour of Maladera matrida Adults in Israel", Phytopareeitica, 17, 2, pp. 81-89, 1989.

GRIMWOOD, B.E. "The Processing of Macadamia Nuts", pp. 3-4, Tropical products Institute, July 1971.

IRONSIDE, D.A. "The Macadamia Flower Caterpilla", Queenaland Agricultural Journal, 104,1, 1978.

MACFALANE, N. HARRIS, R.V. "Macadamia Nuts as an Edible Oil Source", Edited by PRYDE, E.H. PRINCEN, L.H. MUKNERJEE, X.D. American Oil Chemists Society, 1981.

MAALANE, N. HARRIS, R.V. "Extraction of Macadamia Oil Using a Small Expeller", Tropical 8cience, Vol 23, 3, pp. 205-215, 1986.

MEULEN, T. van der, "The Coconut Stink Bug Gets Out of Hand", Information Bulletin, Citrus and Subtropical Fruit Research Institute South Africa, 202, 1989.

PAQUIN, D,G, LAING, T. "Sweeping Efficiencies of a Macadamia Nut Harvester on Difficult Orchard Surfaces", Journal of Agricultural Engineering Research, 45, 2, pp. 8999, 1990.

PEGG, K.G. "Macadamia Trunk Canker Disease", Queensland Agricultural Journal, 99, 11, pp. 595-596, 1973.

QUEENSLAND DEPARTMENT OF PRIMARY INDUSTRIES ENTONOMY BRANCH, "Macadamia Summary of Insect Control Recommendations", Queensland Agricultural Journal, 101, 3, pp.286-290, 1978.

ROSENGARTEN, F. "The Book of Edible Nuts", Walker and Co New York, 1984.

SARIG, Y. GROSZ, F. RASIS, S. "The Development of a Mechanical nut Cracker for Macadamia Nuts", Journal of Agricultural research, 25, 4, pp. 367-374, 1980.

TANG, G.P. "Flash Drying Macadamia Nuts for Improved Kernel Extraction", Transactions of the A.S.A.E. (American Society of Agricultural Engineers), 25, 6, pp. 1733-1736, 1982.

TREVERROW, N. "Monolepta Beetle", Agfacts, No 42, Agricultural Research Centre Wollongbar, New South wales Australia, 1986.

WOODROOF, J.G. "Tree Nuts, Production, Processing, Products, Vol 1.", pp.313-337, AVI Publications Company, 1967.

WYSOKI, M. "New Records of Lepidopterus Pests of Macadamia in , Israel", Phytoparesitica, 14,2, 1986.

Mango seed



Mango Kernel Oil


Mangifera indica








While considerable variations occur depending on variety on average the dry stone makes up some 10% of the fruit weight. The -kernel makes up 75% of the seed weight and contains, on average, 10% oil (Bring)).

It has been estimated that in India alone some 30,000 tons of oil could be extracted from 4 million tons of the total annual harvest of 7 million tons (Bring)). Some mango kernel oil has been commercially extracted in India with 150 tons being exported in 1976 rising to 850 tons in 1978 (Bring)).


The main use of mango is as a fresh fruit and as an ingredient in a wide range of fruit products. The kernels are edible, have a protein content of about 9% and are eaten, particularly in times of food scarcity. Oil is commercially extracted from the kernels in India and finds use as a cocoa butter substitute. The cake remaining after oil extraction is used in animal feed.

The mango tree yields a gum, a tannin and a yellow dye. The bark, leaves and seeds are used to prepare a range of traditional medicines (Narasiahachar).




See standard agricultural texts


In India, April to September.


The fruit is generally harvested by picking from the trees. The major constraint to mango kernel oil production lies in the procurement of stones. These are to be collected by hand for income in a similar way to waste paper etc.




Mango stones have to be dried, usually in the sun, so reducing the kernel moisture content from about 48% to 13%. In India the collection period coincides with the monsoon making drying a problem. Good drying is essential to prevent the growth of the fungus Aspergilla niger and to avoid the development of FFA rancidity. FFA levels in raw stones can rise from 2% to 7% after 20 days and to 46% after 120 days (Bring)).

After drying the stones are decorticated, usually by hand. A continuous mango stone decorticator has been designed (Narasiahachar).




The following system has been used in India. Prior to oil extraction the mango kernels are sieved to remove foreign matter and broken in a hammer mill. The broken kernels are further reduced in size by use of a roller breaker. The material is heated to soften it and finally feed to flaking rollers. The final flakes, which should be very thin and have a moisture content of 10-12% are solvent extracted with hexane (Bring)).


Mango kernel oil is pale yellow in colour. The fatty acid composition varies with both variety and climatic conditions. Typical values are:

Palmitic acid 5.1-8.0%
Stearic acid 42-48%
Oleic acid 35-42%



Driers, decorticators, hammer mills, roller mills, solvent extraction plant.

There is a lack of identifiable information on methods of oil extraction, particularly pressing and expelling are required.



BRINGI, N.V. "Non-Traditional Oilseeds and Oils in India", Oxford & IBH Publishing Co. PVT. Ltd.. New Delhi, India pp 73-95.

NARASIMHACHAR, B.L., et al., J.Oil Technol. Assn. India, 94, 1979

3. ABBIW.D.K.," Useful Plants of Ghana."

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