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Steam distillation of tea tree ( Melaleuca alternifolia ) oil
Author(s) -
Johns Michael R,
Johns Julia E,
Rudolph Victor
Publication year - 1992
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740580109
Subject(s) - melaleuca alternifolia , steam distillation , tea tree oil , maceration (sewage) , chemistry , melaleuca , pulp and paper industry , distillation , chromatography , botany , essential oil , materials science , biology , engineering , composite material
The steam distillation of tea tree ( Melaleuca alternifolia Cheel) oil was investigated in a small batch still to ascertain the effect of operating variables on the yield, composition and rate of recovery of oil. Provided suitable distillation times (2–3 h) were used, the oil yield and composition did not vary with steam rate or pretreatment of the leaves by maceration. However, the rates of recovery of individual oil components were markedly affected. The results demonstrate that the oil components can be divided into two main groups according to their distillation behaviour. Oxygenated components, particularly terpinen‐4‐ol and 1,8‐cineole, are recovered the most rapidly, despite their high boiling points relative to other components. Their rates of recovery are increased with increasing steam rate, but are insensitive to leaf maceration. A second group of components, characterised by either a hydrophobic structure (the monoterpenes) or a larger molecular size (sesquiterpenes), exhibited the opposite behaviour. The rates of recovery of these components were unaffected by steam rate and improved by leaf maceration. It is hypothesised that the rate‐limiting processes for oxygenated and hydrophobic components are different. For the former, recovery is mass‐transfer film controlled, whereas the latter are diffusion controlled. This understanding provides the basis for manipulating oil quality by process conditions.