Identification of volatile compounds in salep (Serapias vomeracea) tubers and effects of harvest time and drying method on composition variation

Abstract

Serapias vomeracea is an economically valuable plant belonging to the Orchidaceae family; particularly, its tubers are consumed as hot drinks. Past studies on S. vomeracea have focused on volatile components only in the aerial parts of this orchid. This study is the first to investigate the volatile compounds present in S. vomeracea tubers, which have a high commercial value. Additionally, we determined the effect of harvest time and drying method on the volatile compound profile. The tubers were harvested on two different days (May 17, 2022, and June 6, 2022) and subjected to four different drying conditions (shade drying, oven drying, shade drying after boiling, and lyophilizer drying). To determine the volatile compound profile, sample extracts were prepared by solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry. Overall, 22 volatile compounds were identified: 3 esters, 3 aldehydes, 3 alcohols, 3 terpenes, 3 alkanes, 3 carboxylic acids, 1 phenol, 1 ketone, 1 lactone, and 1 furan. The results revealed that p-cresol was the main compound. During harvesting and subsequent drying, some compounds were lost, and some new compounds were formed. Moreover, harvest time had quite limited effects on volatile compounds in the lyophilizer method. Cluster analysis revealed that the combination of harvest time and drying was effective in the distribution of volatile compounds in salep powder.