Dynamic analysis of polar metabolites and volatile compounds in sesame seeds during roasting

Background and objectives The changes in polar metabolites and volatiles in sesame seeds during roasting were analyzed to provide new information for the formation mechanism of sesame oil aroma. Findings The results showed that the typical sesame aroma components, heterocyclic compounds, increased with the extension of the roasting time and reached 43.78% at 12 min. However, the proportion of aliphatics and terpenoids decreased with the roasting time. In addition, the main polar metabolites in sesame seeds, free amino acids and monosaccharides, continually decreased from 497.14 mu g/g and 268.85 mu g/g in raw seeds to 144.59 mu g/g and 7.52 mu g/g in 12-min roasted seeds, respectively. Conclusions Based on the changes in specific polar metabolites and volatile compounds, it could be inferred that pyrazines mainly generated through Maillard reaction with Ala and glucose as the possible primary substrates. While S-heterocycles might be mainly formed through the thermal degradation of proteins and subsequent reactions. Significance and novelty: The results of this study provide important information and new details for the aroma formation process of sesame seeds during roasting and would provide a reference for the study and optimization of sesame roasting and oil extraction processes, as well as the development of sesame seed products. In addition, relevant information can also provide clues for the artificial synthesis of sesame seed aroma components.