Differentiation and characterization of volatile organic compounds from different parts of saffron based on HS-SPME-GC-MS

Saffron ( Crocus sativus L. ) is a valuable perennial bulbous medicinal herb, often referred to as the “golden spice”. Although previous studies have investigated the non-volatile components and bioactive constituents in various parts of saffron, comprehensive profiles of its volatile organic compounds (VOCs) remained limited. This study employed headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with cluster heatmaps, principal component analysis (PCA), and orthogonal partial least squares-discriminant analysis (OPLS-DA) to analyze and compare the VOCs in seven parts of Zhejiang-cultivated saffron, namely stigma (SS), petal (SP), pollen (SPO), filaments (SF), corms (SC), buds (SB), and leaves (SL). A total of 72 VOCs of saffron were identified, comprising 10 alcohols, 7 esters, 19 ketones, 7 aldehydes, 17 alkenes, and 12 other compounds. Among these, fatty acid methyl esters were the predominant VOC components in SC, whereas safranal or isophorone exhibited relatively higher abundances in the other six parts, which were also enriched in trimethylcyclohexane or cyclohexene derivatives. Cluster heatmaps and PCA grouped the seven saffron parts into three major clusters: SS, SPO and the remaining five parts. Furthermore, 15 significantly differential compounds were screened using the scatter loading plot (S-plot) of the OPLS-DA model combined with variable importance in the projection (VIP) values. Isophorone, 2,2,6-trimethylcyclohexane-1,4-dione (DOIP), and 2,6,6-trimethyl-1,3-cyclohexadiene-1-carbaldehyde (safranal) were identified as common key discriminant compounds across all comparisons, and while SS, SP, SF, SB and SL each contain unique marker compounds. These findings provide a scientific foundation for the authentication, quality assessment and comprehensive utilization of saffron resources.