A multifunctional baicalein-loaded carboxymethyl chitosan/ectoine film for blueberry preservation: from ultra-high pressure-assisted extraction to antibacterial mechanism and fresh-keeping application.

Postharvest fruit spoilage caused by moisture loss, microbial contamination and oxidative deterioration remains a persistent bottleneck for food preservation. This study developed an integrated strategy for the efficient fabrication of safe, multifunctional food preservation materials using plant-derived antibacterial compounds. Molecular dynamics (MD) simulation was employed to guide solvent selection for the ultra-high pressure extraction (UHPE) of baicalein (BAI). By comprehensively optimizing solvent compatibility, pressure-induced cell disruption and mass transfer efficiency, a maximum BAI yield of 67.29 ± 0.05 mg/g was achieved. The purified BAI effectively inhibited Staphylococcus aureus with MIC and MBC values of 40 and 80 μg/mL, respectively. Mechanistic investigations revealed that BAI interfered with tricarboxylic acid cycle metabolism, disrupted intracellular NAD+/NADH homeostasis, and further induced respiratory energy dysfunction and excessive accumulation of secondary reactive oxygen species, which ultimately caused irreversible damage to bacterial cells. Ectoine (Ect) was innovatively incorporated as an antioxidant component into biocompatible carboxymethyl chitosan (CMCS)-based film, while BAI served as a functional antibacterial and hydrophobic agents. The fabricated BAI-CMCS/Ect film enabled sustained BAI release and improved water barrier properties, thereby effectively alleviating film cracking and fruit moisture loss. Benefiting from the synergistically enhanced antibacterial and antioxidant activities, the film extended the shelf life of blueberry by over 60% under both 25 and 4 °C storage conditions. Collectively, this work establishes a feasible and practical integration strategy combining MD-guided efficient extraction of baicalein, antibacterial mechanism clarification, and multifunctional composite film fabrication, which provides a promising technical approach for postharvest fruit preservation.