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Olearia Phlogopappa: aspects of clonal cultivation and essential oil characterisation

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Dragar, V A(Valerie Annette) (1991) Olearia Phlogopappa: aspects of clonal cultivation and essential oil characterisation. Unspecified thesis, University of Tasmania.

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Abstract

The species Olearia phlogopappa was found to exhibit variation
in both form and essential oil properties in populations around
Tasmania. Six locations, Great Lake, Paradise Plains, Mount
Wellington, Eaglehawk Neck, Elephant Pass and Buckland, were
surveyed for a plant which yielded maximal quantities of
organoleptically suitable essential oil from each site.
Some preliminary morphological, dry matter and infra-red
photographic studies were carried out which revealed a positive
relationship between the rate of dry matter accumulation and height
measurements. This, together with a small scale seasonal variation
trial led to the development of multi-location trials.
A rank order of clones was established on the basis of growth
rate and oil yield. The major source of oil appeared to be the
juvenile leaves in all cases. The effect of harvest was studied
at two trial sites. A combination of a pruning trial and seasonal
variation trials led to the recommendation that Olearia phlogopappa
clones should be grown in a hedgerow and harvested in late summer.
The plants can be cut to a height of approximately 30 cm, and the
regenerative growth may be harvested a second time in August. In
this way, the maximum oil yield may be obtained.
The characterisation of the essential oil of each of six clones
was carried out using a combination of gas chromatography/mass
spectrometry, nuclear magnetic resonance spectroscopy, high
performance liquid chromatography and Fourier transform infra-red
techniques.
The essential oil was pre-fractionated by means of a simple
silica gel column. Through the use of this technique, fractions
were obtained for further characterisation work. The separation
occurred on the basis of polarity, so that hydrocarbons, oxygenated
compounds and alcohols were obtained in separate fractions. This
simplified the hplc purification and subsequent identification by
nmr of several important components. Some 2D nmr experiments, in
addition to standard 1 H and 13C nmr techniques were used. The major
components identified were as follows:
a-pinene, (3-pinene, cineole, linalool, a-terpineol, caryophyllene,
germacrene-D, bicyclogermacrene, spathulenol, a-eudesmol,
13-eudesmol, y-eudesmol, liguloxide, caryophyllene oxide and
kessane.
In addition to the above components, there are some 50 minor
components present in the oils, some of which contribute to the
characteristic tomato, exotic fruity odour of these products.
Changes in oil composition were suspected to be occurring
during the steam distillation process, and these were investigated.
The essential oil released from the plant material was compared to
the release of volatiles from a solvent extract.
The diversity of the clonal material was investigated
concentrating on differences in several morphological features and
growth rates. The seasonal variation of essential oil in the leaves
was monitored and the greatest quantities of oil were found to be
present in late summer, early autumn. The bulk of the oil is
located in the current seasons growth, rather than in matured
leaves. The quality of the oil was also observed to change through
the monitoring of chemical composition.
Organoleptically, the oils from the six clones under
consideration were markedly different from one another. For
instance, the desirable spicey, tomato-like properties were
predominantly found only in one clone. This odour characteristic
was also present in the other oils but was masked or over-ridden by
other exotic fruity notes. In other cases, native bush, floral, or
citrus notes were predominant in the oil.
The major components of the oil were identified as
germacrene-D, bicyclogermacrene and spathulenol. In some instances,
(3-eudesmol or caryophyllene comprised the greatest part of the oil.
However, the greatest contribution to the overall characteristic
spicey odour was made by kessane and liguloxide. Minor components
were not identified, but are also likely to be responsible for the
complex aroma of the oil.
This work makes a contribution to the body of knowledge
relating to essential oils in endemic species. The uniqueness of
Olearia oil is illustrated by its odour, and by its adaptability to
a cropping situation. The commercial production of a natural essence such as this one heralds the inception of a potentially
viable new industry.

Item Type: Thesis (Unspecified)
Copyright Holders: The Author
Additional Information:

Includes bibliography

Date Deposited: 09 Dec 2014 00:16
Last Modified: 11 Mar 2016 05:55
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