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Progress in Essential Oils
By: Brian M. Lawrence
Posted: April 21, 2006, from the May 2006 issue of P&F magazine.
Tea Tree Oil
Tea tree oil has been produced commercially since the late 1920s. Until the 1980s, the industry in Australia produced 5-15 metric tonnes per annum (Davis 1999). By the beginning of the 21st century, this level of production had increased to ca. 300 metric tonnes. As a result, the composition, existence of chemotypes and genuineness of the oil have become subjects of considerable study.
According to the International Standard for tea tree oil (Anon 1996), the compositional requirements for this oil of Melaleuca alternifolia Cheel are as follows:
alpha-pinene (1.0-6.0 percent)
sabinene (t-3.5 percent)
alpha-terpinene (5.0-13.0 percent)
limonene (0.5-4.0 percent)
1,8-cineole (0-15.0 percent)
gamma-terpinene (10.0-28.0 percent)
p-cymene (0.5-12.0 percent)
terpinolene (1.5-5.0 percent)
terpinen-4-ol (> 30.0 percent)
alpha-terpineol (1.5-8.0 percent)
aromadendrene (t-7.0 percent)
delta-cadinene (t-8.0 percent)
globulol (t-3.0 percent)
viridifl orol (t-1.5 percent)
t = trace (< 0.5 percent)
Homer et al. (2001) examined the natural variation of tea tree oil produced from 615 individual trees. Analyses of the oils revealed the existence of six chemotypes: terpinen-4-ol-rich, 1,8-cineole-rich and terpinolene-rich, while the other three were all 1,8-cineole-rich but differed in the terpinolene or terpinen-4-ol levels.
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