Aroma compound analysis of Piper nigrum and Piper guineense essential oils from Cameroon using solid-phase microextraction–gas chromatography, solid-phase microextraction–gas chromatography–mass spectrometry and olfactometry
Introduction
Many essential oils of black pepper (Piper nigrum, Piperaceae family) seeds and leaves from various geographic origins have been analyzed for their aroma components, and more than 250 volatiles have been identified in this valuable spice and flavoring material for food and perfumery products [1], [2], [3], [4], [5]. Using olfactoric evaluations (e.g. aroma extract dilution analysis or the sniffing technique) in combination with gas chromatographic analyses [6], [7], [8], [9] the flavor and off-flavor compounds were found to be monoterpenes, minor aldehydes and pyrazines.
In contrast to the well-known composition of P. nigrum essential oils, the volatiles of the West African pepper (Piper guineense Schum. and Thom., syn. Piper leonense C.DC., Piper famechonii C.DC.; Piperaceae family; so-called “Ashanti pepper”) have been investigated very rarely [10], [11], [12], [13], [14]. Monoterpenes, sesquiterpenes and benzenoids (e.g. dillapiole and myristicin) were identified as the main compounds. In addition to the importance of “Ashanti pepper” as a spice and for the flavoring of food products, this Piper species is also used in traditional African medicine, because of its various pharmacological effects (e.g. antimicrobial, insecticidal, anticonvulsive, antihypertensive, sedative and tranquillizing activities [15], [16], [17], [18], [19]).
An investigation of the aroma compounds of the essential oils of dried fruits of black P. nigrum and black and white P. guineense from Cameroon by means of solid-phase microextraction (SPME), GC, GC–MS, the GC–sniffing technique and olfactometry (odor evaluations) has not been performed previously. Therefore, the objective of this study was to identify the aroma impact compounds of these SPME samples responsible for the characteristic odor of these natural products using the very effective combination of analytical and olfactoric methods given above [20], [21], [22], [23], [24], [25], [26], [27], [28].
Section snippets
Plant material
The plant materials (black Piper nigrum, black and white Piper guineense seeds) were collected from a local market at Douala (Cameroon) in November 1998. The species were identified by a local botanist, and the specimens deposited at the National Herbarium in Yaounde. The seeds were dried naturally at room temperature for 1 month before hydrodistillation.
Isolation of volatile compounds
The three different pepper seed samples (20 g each) were powdered and subjected to hydrodistillation in a Clevenger-type apparatus for 4 h.
Results and discussion
The essential oils of black Piper nigrum and black and white Piper guineense dried seeds were evaluated olfactorically by professional perfumers for their characteristic aroma as follows: fine, pleasant black pepper note with intense pinene and limonene side-notes (P. nigrum); black pepper top-note, nutmeg- and clover-like notes, fruity and herbal/vegetable-like side-notes, in the background fatty-oily (P. guineense, black); and pleasant white pepper note, spicy (direction of clove) and
Conclusion
In summary, we can report that the significant aroma of essential oils of Piper nigrum and of black and white Piper guineense from Cameroon is the result of the odor impression of various identified headspace SPME constituents of the three corresponding oil samples. In particular, mono- and sesquiterpenes were found to be of essential importance for the fine, pleasant pepper aroma (all essential oils), with pinene and limonene (black pepper oil), clove and nutmeg, herbal/vegetable-like and
Acknowledgements
We acknowledge the botanical identification of the plants by Dr. P.M. Mapongmetsem and Dr. S. Yonkeu, botanists of the University of Ngaoundere, and the olfactoric evaluations by Mr. V. Hausmann and Mr. W. Höppner, chief perfumers of Dragoco, Vienna, Austria, as well as the valuable communication on aroma compounds with Dr. F.-J. Hammerschmidt, Dragoco Gerberding, Holzminden, Germany.
References (43)
- et al.
Phytochemistry
(1998) - et al.
J. Ethnopharmacol.
(1993) J. Chromatogr. A
(2001)J. Chromatogr. A
(2001)- et al.
J. Chromatogr. A
(2001) J. Chromatogr.
(1990)J. Chromatogr. A
(1997)- BACIS, Volatile Compounds in Food Database, Pepper, TNO, Zeist, Netherlands,...
- et al.
J. Essent. Oil Res.
(2000) - et al.
J. Essent. Oil Res.
(2001)