Effects of Four Extraction Methods on Volatile Aroma Compounds of Four Osmanthus fragrans Cultivars Based on GC-MS

The volatile aroma of Osmanthus fragrans flowers is governed by both cultivar background and extraction technique, yet their relative contributions remain unquantified. Here, four representative cultivars from Xianning, China—‘Boye Yingui’ (BYYG), ‘Daye Jingui’ (DYJG), ‘Xiaoye Dangui’ (XYDG), and ‘Mantiaohong’ (MTH)—were processed in parallel by solid-phase microextraction (SPME), solvent extraction of intact flowers (IF), solvent extraction of ground flowers (GF), and rotary distillation (RD), and the resulting profiles were analyzed by GC-MS combined with PCA, Venn analysis, and ANOVA. In total, 78 volatile compounds in seven chemical classes were detected across the 16 cultivar–method combinations. Variance partitioning showed that the extraction method, rather than the cultivar, was the dominant source of variation (77.2–79.2% of total variance). RD preferentially enriched alcohols (73.9–78.6%) and esters (up to 19.8%) but largely eliminated aldehydes, alkenes, and alkanes; SPME produced the highest relative proportions of ketones and alkenes in its volatile profile; and GF delivered the broadest compound coverage and the most unique compounds in three of the four cultivars. DYJG accumulated the most linalool (10.6 ± 6.4%), whereas MTH was distinguished by γ-decalactone (11.2 ± 6.6%, reaching 19.3% under RD). A target-component-oriented method–cultivar matching strategy is proposed for the efficient utilization of O. fragrans aroma resources.