Comparative Analysis of Aroma Profiles in Walnut, Pecan and Hickory Nuts During the Roasting Process Using E-Nose, Hs-Spme-Gc-Ms, and Hs-Gc-Ims

Walnut, pecan, and hickory nuts are well known for their nutritional value and outstanding aroma. However, the impacts of thermal processing on their aroma formation are less known. Using electron nose (E-nose), headspace solid-phase micro extraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), aroma profiles during the roasting process were analyzed for identification of potential authenticity markers. Sensory evaluation and E-nose analysis suggested thermal processing significantly impacted sensory characteristic and hickory nuts had a special nutty aroma compared with walnut. HS-SPME-GC-MS and HS-GC-IMS analysis respectively identified 118 volatiles (33 heterocyclic compounds, 18 aldehydes, 11 aromatics, 18 ketones, and others) and 63 volatiles in the three nuts. Notably, some components like 1-octanol, 2-pentyl-furan, hexanal, acetylpyrazine, benzophenone, and octyl ester may participate in unique odors of pecan and hickory nuts. These results provide valuable information for understanding the flavor formation of the three nuts and the optimization of roasting process.