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

The investigation of aroma compounds of the essential oils of dried fruits of black pepper (Piper nigrum) and black and white “Ashanti pepper” (Piper guineense) from Cameroon by means of solid-phase microextraction (SPME) was carried out for the first time to identify the odorous target components responsible for the characteristic odor of these valuable spices and food flavoring products. By means of GC–flame ionization detection (FID) and GC–MS (using different polar columns) the main compounds (concentration >3.0%, calculated as % peak area of GC–FID analysis using a non-polar fused-silica open tubular RSL-200 column) of the SPME headspace samples of P. nigrum (black) and P. guineense (black and white) were found to be: P. nigrum (black)—germacrene D (11.01%), limonene (10.26%), β-pinene (10.02%), α-phellandrene (8.56%), β-caryophyllene (7.29%), α-pinene (6.40%) and cis-β-ocimene (3.19%); P. guineense (black)—β-caryophyllene (57.59%), β-elemene (5.10%), bicyclogermacrene (5.05%) and α-humulene (4.86%); and P. guineense (white)—β-caryophyllene (51.75%), cis-β-ocimene (6.61%), limonene (5.88%), β-pinene (4.56%), linalool (3.97%) and α-humulene (3.29%). The most intense odor impressions of the essential oils of the various dried pepper fruits were given by professional perfumers as follows: P. nigrum (black)—fine, pleasant black pepper note; P. guineense (black)—black pepper top-note; and P. guineense (white)—pleasant white pepper note. These analytical results for the SPME headspace samples of three different pepper species from Cameroon are in accordance with the olfactoric data of the corresponding essential oils. A GC–sniffing technique was used to correlate the single odor impression of the identified SPME headspace volatiles of the three investigated pepper samples with the following results: the main compounds such as β-caryophyllene, germacrene D, limonene, β-pinene, α-phellandrene and α-humulene, as well as minor constituents such as δ-carene, β-phellandrene, isoborneol, α-guaiene, sarisan, elemicin, calamenene, caryophyllene alcohol, isoelemicin, T-muurolol, cubenol and bulnesol, are of greatest importance for the characteristic pepper odor notes of these three Piper samples. Further aroma impressions can be attributed to mono- and sesquiterpenes, hexane, octane and nonane derivatives.