Antimicrobial-releasing films and coatings for food packaging based on carvacrol and ethylene copolymers

Abstract

Efficiency in antimicrobial packages based on the release of active agents depends on their retention into the packaging materials and on the extent and rate of their release to the package headspace. In this work, the effects of polymer chemical composition and matrix morphology on the release of carvacrol were explored. Films and coatings containing carvacrol, and manufactured from four polyolefin latexes of a range of polarities (ethylene-octene (LLDPE) < ethylene-vinyl acetate (EVA) < < ethylene-methacrylic acid (EMA) ≈ ethylene-alkaline methacrylate (ION)), were characterized in terms of their active and functional properties. Scanning electron microscopy images evidenced that films presented heterogeneous structures caused by an incomplete coalescence of their polymeric particles. Consequently, different film structures of decreasing heterogeneity, porosity and roughness (LLDPE > EVA > > ION > EMA) were obtained, exhibiting morphologies generally correlated with the melting temperatures and active behaviours of the polymers. LLDPE and EVA, the most heterogeneous polymers, were generally more permeable, less resistant, more deformable, less transparent and more wettable than EMA and ION, of coalesced structure. For carvacrol, LLDPE and EVA yielded higher values of the diffusion coefficient, in agreement with their permeability results, whereas EMA and ION showed higher solubilities, according to their greater affinity for the active molecule, as derived from their ionic nature. The evolution of the release of carvacrol from the studied films was experimentally measured and theoretically predicted through determination of its solubility and diffusivity parameters. Excellent agreement between both experimental and predicted data was finally observed.

Development of Bilayer Biodegradable Composites Containing Cellulose Nanocrystals with Antioxidant Properties

“…As release kinetic curves in Figure 5 and RMSE values in Table 5 show, theoretical curves greatly fitted with the experimental data, showing that release of quercetin from bilayer PLA/ZN composites was principally controlled by the diffusion phenomenon in the zein layer defined by the second Fick's law. This behavior was in agreement with the release of other active agents from zein layer and films [50][51][52]. The curve slope of quercetin kinetic releases depended on the presence of CNC in the zein layer and on the type of food simulant.…”

Chromatic Sensor to Determine Oxygen Presence for Applications in Intelligent Packaging

“…The microstructural morphology of the sensor film was analysed by field emission scanning electron microscopy on the surface of a cryogenic fracture, following the procedure reported by Cerisuelo, et al [19]. A digital image of the final sensor structure obtained industrially was acquired with an Eclipse 90i Nikon microscope (Nikon Corporation, Tokyo, Japan) with a 16× objective equipped with a digital camera (Nikon DS-5Mc, Nikon Corporation, Tokyo, Japan).…”

Antimicrobial packaging based on a LAE containing zein coating to control foodborne pathogens in chicken soup

“…Films exposed to these food simulants were dried in a dessicator for 12 h, and immersed in liquid nitrogen where they were cryofractured. The fracture surface was analysed by field emission scanning electron microscopy on the surface of a cryogenic fracture, following the procedure reported by Cerisuelo et al (2015). SEM analysis was carried out using an S-4800 unit (Hitachi Ltd, Tokyo, Japan) equipped with an FEG electronsource, a BSE detector and an image capture system, using an accelerating voltage of 10 kV.…”