Unraveling the influence of lipids on aroma formation during microwave roasting of hazelnuts based on lipidomics

• This study first integrates lipidomics and volatile organic compounds (VOCs) profiles to investigate the impact of lipids on aroma formation in microwave-roasted hazelnuts. • The 23 differential lipids and 22 key differential VOCs can be used as potential markers to distinguish between different microwave treatment groups. • Correlation analysis showed that PC (18:4/18:1), PC (18:0/18:2) and PE (22:5/18:1) are the key lipids that form the burnt aroma of hazelnuts after microwave roasting. To elucidate the relationship between the generation of volatile organic compounds (VOCs) and lipid modifications during the microwaving of hazelnuts, HS-SPME-GC/MS and UHPLC-QE Orbitrap/MS/MS were used to determine the lipid and VOC changes of hazelnuts under different microwave treatment conditions. A total of 1244 lipids and 124 VOCs were identified, from which 23 significantly different lipids and 22 key aroma substances were selected. Phosphatidylcholines (PCs) and phosphatidylethanolamines (PEs) were significantly up-regulated in microwaved hazelnuts, while triglycerides (TGs) were significantly down-regulated. Lipids were dominated by TGs in raw hazelnuts compared to microwave-treated hazelnuts. Further analyzed by Spearman correlation, PC (18:4/18:1), PC (18:0/18:2), and PE (22:5/18:1) were the key lipids for the formation of pyrazines, and TGs were the main source of fruity and nutty aromas in raw hazelnuts. The present study reveals a correlation between hazelnut lipid changes and their VOCs formation.