Mechanisms underlying the regulation of anthocyanin metabolism in postharvest blueberries by microcapsule-containing thymol coatings

This study developed a novel microcapsule-containing thymol (THY) coating to stabilize anthocyanin accumulation in postharvest blueberries and to elucidate its underlying regulatory mechanism. The microcapsules were fabricated using β-cyclodextrin (β-CD) modified with polyethylene glycol 6000 (PEG6000) and sucrose fatty acid ester (SE-15). An orthogonal experimental design was employed to optimize the preparation process. The optimized controlled-release coating stabilized THY release while enhancing its antioxidant and antimicrobial properties. Among the coatings with different THY concentrations, the coating containing 30 mg·L⁻¹ THY (CR-30) most effectively preserved blueberry quality and promoted anthocyanin accumulation by regulating the activity of key enzymes related to anthocyanin metabolism. Integrated metabolomic and transcriptomic analyses of the CR-30 treatment identified 20 differentially accumulated metabolites (DAMs), which were enriched in anthocyanin, flavonoid, and related biosynthesis pathways, alongside 21 differentially expressed genes (DEGs) involved in anthocyanin synthesis. Furthermore, key differential transcription factors, including MYB, WRKY, and bHLH, showed significant correlations with the DAMs and DEGs, highlighting their regulatory roles in anthocyanin metabolism. This study elucidates the regulatory mechanisms of THY on anthocyanin metabolism, providing a theoretical foundation for the development of innovative postharvest quality management technologies in blueberries.