Comparative Analysis of Volatile Fingerprints and Aroma-Active Compounds in Green and Red Sichuan Pepper Essential Oils Using GC-IMS and GC-O-MS.

Green (Zanthoxylum schinifolium, ZSEO) and red (Zanthoxylum bungeanum, ZBEO) Sichuan pepper essential oils are widely used spices whose characteristic aromas differ markedly, yet a systematic comparison of their volatile fingerprints and aroma-active compounds is still lacking. To address this, the two essential oils were characterized and compared by combining headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS). HS-GC-IMS detected 94 volatile signals; multivariate analysis clearly separated the two oils (R2Y = 0.993, Q2 = 0.986) and identified 40 differential markers including 37 aroma-active compounds, with ZSEOs enriched in minty and green-note compounds like isomenthone and ZBEOs in woody, ester and acid compounds such as bornyl acetate. GC-O-MS identified 37 aroma-active compounds, of which linalool was the most prominent odorant in both Eos; a total of 27 were shared, while four and six were unique to the green and red EOs, respectively. Cross-referencing the two datasets showed that volatile abundance and odor contribution were not always concordant. The combined approach clarifies the chemical basis of the aroma difference between the two species and offers a transferable strategy for linking volatile fingerprints to perceived aroma in Zanthoxylum essential oils.