Paper presented at the IFEAT Int. Conference in Cape Town

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Species identity in plantationsBecause vegetative propagation wasnot developed until recently, all ofthe early buchu plantations wereestablished using individualseedlings and there has often beengreat confusion regarding geneticidentity of many plantations [6] .In particular, A. crenulata and thehybrid A. betulina x crenulata plantsare practically identical, even beyondthe seedling stage.To add to this confusion, the two phenotypically indistinguishable chemotypes of A. betulina (adiosphenol and an isomenthone chemotype), with drastically different essential oil compositions, areoften found mixed in plantations.These factors, together with competitive behaviour of some oil distillers and the lack of sufficientanalytical facilities, have caused great confusion regarding the production of the individual species andchemotypes of buchu oil. Many a farmer has ended up with a beautiful field of cultivated A. crenulataplant material instead of the more valuable A. betulina that he intended to cultivate, ditto regarding thechemotypes of A. betulina.Furthermore, these confusions have even filtered through to the oil market with the result that eventoday some of the largest traditional users of buchu oil for flavour and fragrance applications havespecifications for ‘Betulina buchu oil’, which is in fact obtained from A. crenulata, or worse a ‘secret’mixture of A. betulina and A. crenulata.The species buchu oil that a client requires is sometimes not mentioned at all, thus putting the onus onthe distiller to exhaustively match a specific client’s specification. Even when ‘Betulina buchu oil’ isrequested, the chemotype is never known until a sample is approved. Clearly this situation is not ideal.Interestingly, it is our experience that very rarely are pure forms of either chemotypes of A. betulinarequired.There is currently no ISO standard for buchu oil(s), and only general CAS and FEMA numbers (CAS:68650-46-4; FEMA: 2169) are assigned to ‘Buchu oil’, representing all the various types and speciesof buchu oil available.Essential oil chemistryModern gas-chromatographic analyses have made the identification of the exact species / chemotypeof buchu plant material a routine exercise.A. betulina (both chemotypes), A. crenulata and A. betulina x crenulata essential oils all containnearly the same chemical components, but in greatly varying amounts:• The main flavour contributors in buchu oils are the unique high-boiling 8-mercapto-pmenthan-3-one(FEMA 3177) isomers and their acetates, 8-acetylthio-p-menthan-3-one(FEMA 3809) [4,7,8] .101
• Other major components in buchu oils, pinene (α- and β-), myrcene, d-limonene,menthone/isomenthone, ocimene, linalool, pulegone and diosphenols play minor, but notinsignificant, roles in the organoleptic properties of buchu oils.It is only the greatly varying concentrations of diosphenols vs. menthone/isomenthone that sets the oilsof the different chemotypes of A. betulina apart. Both, however, owe their uniquely buchucharacteristic organoleptic properties to their 8-mercapto-p-menthan-3-one isomer content (for whichbuchu is the only botanical source of this important sulphur containing high-impact aroma chemical).By GC (FID) analysis, commercial A. betulina essential oils are generally characterised by relativelylarge amounts of d-limonene, menthone/isomenthone or diosphenols (0-45% combined Ψ-diosphenoland diosphenol and/or menthone/isomenthone with the relative concentration of one, at the expense ofthe other), relatively small amounts of pulegone (typically
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Paper presented at the IFEAT Int. Conference in Cape Town

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