Volatile and capsaicinoid composition of ají (Capsicum baccatum) and rocoto (Capsicum pubescens), two Andean species of chile peppers.

Background: Ají (Capsicum baccatum L. var. pendulum) and rocoto (Capsicum pubescens R. & P.) are two species of chile pepper used for millennia in Andean cuisine. The introduction of these relatively unknown Capsicum species to new markets requires an understanding of their flavour-related compounds. Thus both heat level (Scoville method and gas chromatography/mass spectrometry (GC/MS)) and, particularly, aroma (headspace solid phase microextraction and GC/MS/olfactometry) were studied in different accessions of ají and rocoto and a C. chinense control.

Results: Ajíes and rocotos are mildly pungent compared with C. chinense (13-352 vs 1605 mg kg(-1) total capsaicinoids). More than 200 volatiles were detected and marked differences in volatile pattern were found between the studied accessions. The powerful fruity/exotic aroma of the C. chinense control is due to esters such as ethyl 4-methylpentanoate, norcarotenoids such as β-ionone and the hydrocarbon ectocarpene. In contrast, the Andean peppers had more earthy/vegetable/bell pepper-like aromas. Rocotos also exhibited a distinct additional cucumber odour, while one of the ajíes had a distinctive sweet/fruity note. The aroma of C. pubescens fruits is mainly due to substituted 2-methoxypyrazines and lipoxygenase cleavage products (e.g. 2-nonenals, 2,6-nonadienal). 2-Heptanethiol, 3-isobutyl-2-methoxypyrazine and several phenols (e.g. guaiacol) and terpenoids (e.g. α-pinene, 1,8-cineol, linalool) are the basis of C. baccatum aroma, with some 3-methyl-2-butyl esters contributing to fruity notes.

Conclusion: In this study the compounds responsible for heat and aroma in the Andean peppers C. baccatum and C. pubescens were identified. The results will be of use to inspire future studies aimed at improving the flavour of these species.