Characterization of the Key Aroma Compounds in Fresh Leaves of Garden Sage (<i>Salvia officinalis</i> L.) by Means of the Sensomics Approach: Influence of Drying and Storage and Comparison with Commercial Dried Sage

Abstract

The overall aroma profiles of commercial dried sage differ significantly from the profile of macerated fresh leaves. To clarify changes in the key aroma compounds, first an aroma extract dilution analysis was applied on an extract/distillate prepared from the fresh leaves of Italian garden sage cultivated in a green house in Germany. Among the 39 aroma active compounds characterized, (<i>Z</i>)-3-hexenal, 1,8-cineol, borneol and eugenol showed the highest flavor dilution (FD) factors. Odorants identified with FD factors between 64 and 8192 were quantitated to calculate odor activity values (OAV; ratio of concentration to odor threshold). The highest OAVs were determined for myrcene, (<i>Z</i>)-3-hexenal, (1S,2R,4S)-borneol and 1,8-cineol. A mixture of 22 key reference aroma compounds in the same concentrations as determined in the fresh sage leaves successfully mimicked the overall aroma profile of the spice. To get insight into changes induced by drying, all key aroma compounds were quantitated in sage leaves from the same plant by drying at 50 °C. While all monoterpenes remained nearly unchanged during drying, in particular highly volatile compounds such as dimethyl sulfide or 2- and 3-methylbutanal were decreased. Almost a total loss occurred for 3-(methylthio)propanal, phenylacetaldehyde, and (<i>Z</i>)-3-hexenal. By contrast, storage of the dried leaves for 12 months at room temperature in the dark did not much effect the concentrations of selected key odorants, thus indicating that drying is the most important factor for the changes in aroma compounds. Sensory profiling of six commercial sage samples showed different aroma profiles, which also clearly differed from the profile of the sage dried in lab scale, which was rated to elicit the most typical sage aroma. In addition, the concentrations of selected key aroma compounds as well as the total amount of volatiles were clearly lower in all commercial samples.