Macadamia integrifolia Maiden & Betche - Proteaceae - macadamia nut, Queensland nut, Macadamia
Evergreen tree, native to Australia, cultivated elsewhere as a fruit tree or namental (Hawaii, Africa, Brazil, Mexico).
„Three of the four species - Macadamia integrifolia, Macadamia ternifolia, and Macadamia tetraphylla - are of commercial importance.“ https://en.wikipedia.org/wiki/Macadamia
„The family Proteaceae includes about 10 species of the genus Macadamia, two of which produce edible nuts: M. integrifolia and M.tetraphylla or hybrids of these. The major species of commerce is M.integrifolia. Macadamia nuts are native to Australia and are produced there as well as in Hawaii, Central and South America and parts of Africa. Nearly all production consists of grafted trees of cultivars developed in Hawaii or Australia. The edible kernel is enclosed in a thick, hard shell that, in turn, is enclosed in a husk that separates from the tree at about the time the seed is mature. The kernel is nearly spherical, consisting of joined equal-sized halves, ie., cotyledons.“ http://www.fruitservices.com/hb66/157macadamia.pdf
Dimethylsulfide, methylpropanal, 2-methylbutanal and 3-methylbutanal have been found in the headspace of roasted Macadamia integrifolia nuts. Important components of the dichloromethane extracts were pyrazines like 2,5-dimethylpyrazine and 2-ethyl 3,5-dimethylpyrazine and phenylacetaldehyde e.g.
[Crain, W.O., and Tang C.S. „Volatile components of roasted macadamia nuts.“, Journal of Food Science, Volume 40 (1), 1975, 207-208]
„The volatile constituents macadamia nuts play an important role in the flavour quality characteristics of this nut… In this study, simultaneous steam distillation-solvent extraction (SDE, water; ether/pentane) was compared to high-vacuum distillation for extracting the volatile compounds present in raw/wet, raw/dry and roasted kernels of Macadamia integrifolia var 344. SDE was found to be more effective in extracting the volatile compounds. The concentrated ether/pentane extracts were analysed using gas chromatography (GC) and gas chromatographymass spectrometry (GC-MS) to identify and quantify the individual volatile compounds. Several compounds were identified including several benzene derivatives, aliphatic compounds, pyrazines, pyridines, furans and sulphur compounds. There were a significant number of volatile compounds produced during the drying and roasting processes that may contribute to the unique flavour of this nut. The main volatile compounds identified in raw/wet, raw/dry and roasted macadamia kernels were dihydro-2-methyl-3(2H)-furanone-, furfural, phenol, benzeneacetaldehyde, 5-methyl-2-furancarboxaldehyde, benzyl methyl ketone, nonanal, and benzenepropanal. However, in raw/dry and roasted macadamia kernels, other volatiles were identified including sulphur compounds and pyrazines, which may also contribute to the characteristic macadamia flavour. “
[Netiwaranon, S., Mason, R., & D'Arcy, B. R. (2000). Volatile constituents in macadamia nuts. In 33rd Annual Convention of Australian Institute of Food Science & Technology (pp. 26-26). Australian Institute of Food Science & Technology]