Aroma‐impact compounds in Lysimachia foenum‐graecum extracts

Two different extraction methods were used to obtain representative extracts from stems and leaves of Lysimachia foenum‐graecum, a Chinese plant with a smoky, spicy, green, woody and caramel aroma. An extract was obtained by steam distillation followed by pentane back‐extraction. Plants were also extracted with dichloromethane, and the non‐volatile compounds were separated from volatiles by high‐vacuum distillation (SAFE). Compared to the steam distillate extract, the SAFE‐distilled extract was judged to be more similar to the aroma of the starting materials. The aroma‐impact compounds of the SAFE extract were then determined using multidimensional GC. From the detection frequencies and the intensities of the peaks, 47 peaks with odour‐activity were determined, using an adaptation of the GC–SNIFF method, to have an impact on the overall aroma of the extract. Fifty‐four compounds responsible for the peaks presenting odour‐activity were identified from mass spectral data, retention indices, olfactory character and co‐injection of authentic standards.