The application of nanofibrillated cellulose (NC) films in packaging industry has been hindered by its lack of heat-sealing ability. Incorporation of NC films with the biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE) laminates can take advantage of each material and endow the films with novel functions for food packaging applications. In this study, a coating that consists of NC and nisin was applied onto a cold plasma treated BOPP/LDPE film to fabricate a novel active packaging with an improved oxygen barrier performance and an added antimicrobial effect. The results showed that cold plasma treatment improved the surface hydrophilicity of BOPP/LDPE films for better attachment of the coatings. NC coatings significantly enhanced oxygen barrier property of the BOPP/LDPE film, with an oxygen transmission rate as low as 24.02 cc/m 2 •day as compared to that of the non-coated one (67.03 cc/m 2 •day). The addition of nisin in the coating at a concentration of 5 mg/g caused no significant change in barrier properties but imparted the film excellent antimicrobial properties, with a growth inhibition of L. monocytogenes by 94%. All films exhibit satisfying mechanical properties and transparency, and this new film has the potential to be used as antimicrobial and oxygen barrier packaging.
In order to isolate cinnamyl acetate (CAc) and cinnamaldehyde (CA), which coexist in cinnamon oil, a crosslinked polymer of b-cyclodextrin polyurethane (CDPU) was synthesized via a facile route and investigated as a selective adsorbent. The successful crosslinking was confirmed by FTIR, TG-DSC, XRD, SEM and N 2 adsorption-desorption analysis. The adsorption mechanism was investigated through a series of instrumental analyses and theoretical calculations, indicating that the combination of noncovalent interactions (e.g., hydrogen bonding, hydrophobic interactions) accounts for the superior affinity of CAc to CDPU, compared with CA. The adsorption behaviors of CAc and CA on CDPU were performed in the static adsorption mode, in which CDPU exhibited a selective adsorption property to CAc. The adsorption kinetics and isotherms in a single component system agreed well with the pseudosecond-order kinetic model and Freundlich isotherm model, respectively. It is noteworthy that the equilibrium adsorption amount was enhanced in the presence of the co-solute, presumably resulting from the cooperative effect arising from Lewis acid-base and p-p stacking interactions between the adsorbed CAc and CA molecules. Due to the stronger adsorption affinity of CAc to CDPU, adsorption enhancement of CAc in the presence of CA is greater than that of CA in the presence of CAc, resulting in higher CAc/CA selectivity with increasing concentrations of the equimolar mixture of CAc and CA.Additionally, CDPU could be easily regenerated and maintained high adsorption capacities and separation efficiency even after six adsorption/desorption cycles.
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