Engineering of ex-situ modified bacterial cellulose nanofibers as well-interconnected sandwich-type film for active packaging application.

In this study, a cost-effective biodegradable film-based high-performance food packaging film was developed utilizing bacterial cellulose (BC) nanofiber with polycaprolactone (PCL) and zinc metal-organic framework (Zn-MOF: MOF-5 and ZIF-8) as an efficient coating layer for sandwich-type food packaging films. This study focuses on enhancing the properties of PCL-BC film by the integration and addition of two different properties of ZnMOF in PCL. The presence of intermolecular interactions among BC, PCL, and Zn-MOF leads to superior adhesion and coating layer among the components results in remarkable film-forming capability. The BC film is effectively sandwiched between the PCL-ZnMOF coating layers on both sides. The ZnMOF formed as ZnBDC (Zn with 1, 4-benzene dicarboxylic acid) and incorporated in the PCL-BC-ZnBDC showed outstanding properties among the other films. The PCL-BC-ZnBDC composite film exhibited an efficient water contact angle (75.03°), water vapor permeability (1.43 × 10-10 g.m-1.s-1.Pa-1), mechanical properties (tensile strength: 26.34 MPa), which is more effective than the pristine BC and PCL films, and more favorable for food packaging applications. The PCL-BC-ZnBDC demonstrates impressive preservation abilities for cut cherry tomatoes (Solanum lycopersicum var. Cerasiforme), maintaining a considerable level of visual freshness during the initial days and exhibiting minimal visible deterioration by day 7 based on photographic observations. The PCL-BC-ZnBDC nanocomposite films showed impressive effectiveness against E. coli and S. aureus bacteria, with a zone of inhibition value of 6.89 ± 0.2 and 9.32 ± 0.2 mm, respectively. The findings indicate that the developed biodegradable film PCL-BC-ZnBDC shows considerable potential as a material for the postharvest preservation of fruits.