Roasting-induced changes in the metabolite profile of laver (Neopyropia yezoensis): Focus on mycosporine-like amino acids and antioxidant activity.

This study investigated non-volatile metabolites in laver (Neopyropia yezoensis) roasted under different temperature/time conditions. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based metabolomics identified 69 metabolites, including mycosporine-like amino acids (MAAs) and their dehydrated derivatives. Multivariate analysis showed that dehydrated MAAs were among the key roasting-responsive metabolites. As roasting intensity increased, MAAs decreased to 0.08-fold of the initial value, while dehydrated MAAs increased 1.22- to 13.61-fold. Antioxidant activity increased, with ABTS+ radical scavenging activity and FRAP exhibiting maximum increases of 4.55- and 4.18-fold, respectively. Pearson's correlation analysis revealed strong positive associations (r > 0.93) between dehydrated MAAs and antioxidant activity. This pattern is consistent with the extended conjugation and enhanced electron delocalization of dehydrated MAAs, which may facilitate radical stabilization. These findings provide insight into metabolite and antioxidant activity changes during roasting and offer fundamental data for optimizing roasting conditions.