Extrusion Blow‐Moulded Oregano Essential Oil/Poly(butylene adipate‐co‐terephthalate) Functional Films for Citrus Preservation

ABSTRACT

Essential oils are promising active agents for food packaging, but their volatility and limited thermal tolerance hinder incorporation into melt‐processed films. Herein, oregano essential oil (OEO)/β‐cyclodextrin (β‐CD) inclusion complexes (CD‐O) were fabricated to improve the handling and thermal retention of OEO during melt processing. The synthesized CD‐O was blended with poly(butylene adipate‐co‐terephthalate) (PBAT) via extrusion blow moulding to prepare biodegradable active packaging films. The resultant CD‐O achieved 61.0% encapsulation efficiency and an inhibition‐zone diameter of 22.60 ± 1.31 mm against Penicillium digitatum . Its dispersion at 10.0 mg/mL exhibited a DPPH radical scavenging rate of 75.6%. The release behaviour of OEO from CD‐O in n ‐hexane followed the Higuchi model ( R ²  = 0.9961), consistent with sustained release under the tested conditions. Thermogravimetric characterization validated that the initial volatilization temperature of OEO in CD‐O increased to 150°C, representing greatly enhanced thermal stability. CD‐O mitigated the loss of tensile strength and the increase in water vapour permeability associated with β‐CD addition. At 15% CD‐O loading, oxygen transmission rate was not significantly different from that of neat PBAT. For P. digitatum ‐inoculated Bingtang oranges, CD‐O/PBAT composite film delayed the onset of disease symptoms by 2 days. For fresh oranges, the composite film suppressed fruit respiration intensity and weight loss and maintained high levels of ascorbic acid and total phenols throughout storage. This work supports the feasibility of melt‐processed CD‐O/PBAT films for active citrus packaging, which possess great potential for fruit preservation.