Comparative analysis of flavor profiles in Chinese hybrid hazelnut (Corylus heterophylla × Corylus avellana) under different roasting conditions using HS-SPME-GC-MS and UPLC-MS/MS.

Roasting impacts the sensory and quality of hazelnuts, yet the metabolic mechanisms underlying thermal-induced flavor changes remain unclear. This study investigated the effects of temperature and duration on the sensory attributes and metabolite profiles of 'Dawei' hazelnuts. Sensory evaluation identified optimal roasting conditions (110 °C_150 min, 130 °C_50 min, 150 °C_35 min) that balanced nutty aroma, color, and texture. HS-SPME-GC-MS identified 147 volatile organic compounds (VOCs), with carbonyls (e.g., E-2-nonenal), pyrazines (e.g., trimethyl-pyrazine) and esters (e.g., hexanoic acid, ethyl ester) significantly correlated with flavor and sensory indices (p < 0.05). UPLC-MS/MS identified 72 core non-VOCs linked to 46 significantly enriched metabolic pathways in roasted groups (p < 0.05). Correlation and KEGG enrichment analyses determined key pathways driving flavor formation: tryptophan metabolism (core non-VOC: 5-(2'-carboxyethyl)-4,6-dihydroxypicolinate) regulated browning and aroma, while arginine/proline metabolism (core non-VOC: L-phosphoarginine) modulated taste and color. These findings reveal key metabolic shifts driving hazelnut flavor development and provide a basis for optimizing roasting strategies.