GC trace of <strong>the</strong> essential oil of A. betul<strong>in</strong>a (isomenthone chemotype).In addition to conta<strong>in</strong><strong>in</strong>g all of <strong>the</strong> above-mentioned compounds (<strong>in</strong> different amounts), A. crenul<strong>at</strong>aessential oils also conta<strong>in</strong> <strong>the</strong> high olfactory impact cis/trans-8-acetylthio-p-menthan-3-one isomers.By GC (FID) analysis a typical commercial A. crenul<strong>at</strong>a essential oil conta<strong>in</strong>s 10-20% limonene, 5-15% menthone/isomenthone, 35-55% pulegone, 0-5% diosphenols (comb<strong>in</strong>ed Ψ-diosphenol anddiosphenol), 0.5-3.5% cis/trans-8-mercapto-p-menthan-3-one isomers <strong>in</strong> a 8:1 to 4:3 trans:cis isomerr<strong>at</strong>io, and <strong>the</strong> unique cis/trans-8-acetylthio-p-menthan-3-one isomers, 1-6%, <strong>in</strong> a ~10:1 trans:cisisomer r<strong>at</strong>io.GC trace of <strong>the</strong> essential oil of A. crenul<strong>at</strong>a.103
A. betul<strong>in</strong>a x crenul<strong>at</strong>a essential oils tend to show a lot of vari<strong>at</strong>ion <strong>in</strong> <strong>the</strong>ir chemical compositions,presumably due to <strong>the</strong> degree of hybridiz<strong>at</strong>ion and/or <strong>the</strong> chemotype of A. betul<strong>in</strong>a genetic m<strong>at</strong>erialth<strong>at</strong> was <strong>in</strong>volved <strong>in</strong> <strong>the</strong> cross<strong>in</strong>g. These oils are never<strong>the</strong>less generally characterized by GC (FID) ashav<strong>in</strong>g a medium limonene level (15-25%), vary<strong>in</strong>g concentr<strong>at</strong>ions of menthone/isomenthone (0-20%), with correspond<strong>in</strong>gly <strong>in</strong>versely vary<strong>in</strong>g diosphenol (Ψ-diosphenol and diosphenol comb<strong>in</strong>ed)concentr<strong>at</strong>ions (0-20%), medium to high pulegone concentr<strong>at</strong>ions (15-40%), vary<strong>in</strong>g amounts ofcis/trans-8-mercapto-p-menthan-3-one isomers (<strong>in</strong> a 1:4 to 3:4 trans:cis isomer r<strong>at</strong>io, but always moretrans than cis isomers present) and vary<strong>in</strong>g amounts of cis/trans-8-acetylthio-p-menthan-3-oneisomers (0.1-2%, <strong>in</strong> <strong>the</strong> same 8:1 trans:cis isomer r<strong>at</strong>io found <strong>in</strong> A. crenul<strong>at</strong>a oil).GC trace of <strong>the</strong> essential oil of A. betul<strong>in</strong>a x crenul<strong>at</strong>a (typical)Although <strong>the</strong> identity of each of <strong>the</strong> compounds found <strong>in</strong> buchu oils has been known s<strong>in</strong>ce 1975 [4] , itwas not until 1996 th<strong>at</strong> <strong>the</strong> exact chemotaxonomy of <strong>the</strong> various buchu oils was described [3] . Until<strong>the</strong>n <strong>the</strong> chemical composition of a general ‘buchu oil’, which could chemically look like any of <strong>the</strong>oils described above (or any mixture of <strong>the</strong>m), was gre<strong>at</strong>ly dependant on <strong>the</strong> <strong>in</strong>itial historicalagricultural source of <strong>the</strong> oil. In th<strong>at</strong> <strong>the</strong> unique olfactory properties of each <strong>in</strong>dividual type of buchuoil was never formally described, due to <strong>the</strong> failure of buchu oil distillers to recognize or haveknowledge of <strong>the</strong> various types of buchu oils available, <strong>the</strong> use of each type of buchu oil forspecialized applic<strong>at</strong>ions is poorly developed, <strong>the</strong>reby limit<strong>in</strong>g <strong>the</strong> use of buchu oil to fewerapplic<strong>at</strong>ions than <strong>the</strong>ir potential.Oils from specific species / chemotypes or blends of species / chemotypes may <strong>in</strong>deed have a desiredeffect <strong>in</strong> specific applic<strong>at</strong>ions. Fur<strong>the</strong>rmore, <strong>in</strong>consistencies <strong>in</strong> chemical compositions, and <strong>the</strong>reforealso olfactory characteristics, of general ‘buchu oils’, as a result of <strong>the</strong> vari<strong>at</strong>ions <strong>in</strong> oils and <strong>the</strong>historical <strong>in</strong>ability to accur<strong>at</strong>ely determ<strong>in</strong>e and control any such vari<strong>at</strong>ions, have certa<strong>in</strong>ly also brandedbuchu oil as a raw m<strong>at</strong>erial of <strong>in</strong>consistent quality <strong>in</strong> <strong>the</strong> past. Large scale harvest<strong>in</strong>g / poach<strong>in</strong>g ofbuchu from wild sources, where many uncontrollable factors (e.g. wild fires, droughts, pests etc.)come to play, fur<strong>the</strong>rmore, made <strong>the</strong> availability of buchu plant m<strong>at</strong>erial <strong>in</strong>consistent, to say <strong>the</strong> least.When comb<strong>in</strong><strong>in</strong>g variablility of supply with gre<strong>at</strong> vari<strong>at</strong>ions <strong>in</strong> composition / quality, it becomesobvious why buchu oil rema<strong>in</strong>ed a niche product <strong>in</strong> <strong>the</strong> flavour and fragrance <strong>in</strong>dustry for such a long104
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