Odour-active compounds in the traditional Armenian soup seasoning herb Heracleum transcaucasicum

The volatile fraction isolated from dried shoots of Heracleum transcaucasicum Manden (syn. Heracleum pastinacifolium C. Koch) by solvent extraction and solvent-assisted flavour evaporation was screened for odour-active compounds by application of an aroma extract dilution analysis. In the flavour dilution (FD) factor range of 1–2048, 51 odorants were detected, among which soup seasoning-like smelling sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) showed the highest FD factor (2048). Its characteristic odour, which closely matched the overall aroma of the dried shoots, in combination with its high FD factor and the absence of any further odour-active compound exhibiting a similar smell, suggested that sotolon constitutes the character impact compound in the aroma of H. transcaucasicum. Stable isotope dilution quantitation using (¹³C₂)sotolon as internal standard revealed a concentration of ~12 mg/kg sotolon in dried H. transcaucasicum shoots, which is several orders of magnitude higher than its odour detection threshold. Further quantitation experiments revealed that during traditional culinary use, sotolon is transferred from H. transcaucasicum shoots in odour-active amounts to Armenian karshm soup.