Abstract
Microcellular nanocomposite foams functionalized with cinnamaldehyde (Ci) were obtained through two-step supercritical foaming and impregnation processing. PLA nanocomposite foams with different C30B concentrations (1, 2, and 3 wt.%) were obtained by foaming with scCO2 at 25 MPa and 135 °C and impregnated with Ci at 12 MPa and 40 °C. The effect of the C30B content and Ci incorporation on the morphological, structural, thermal, and release properties of the developed foams were investigated. The incorporation of Ci was not influenced by C30B’s addition. The presence of C30B and Ci incorporation reduced the average pore diameter slightly and the crystallinity degree of the foams extensively. Simultaneously, the experimental and theoretical characterization of the Ci release from the PLA nanocomposite foams in EtOH 50% was analyzed. The mechanism of Ci release from the foams was defined as a quasi-Fickian diffusion process that could be successfully described using the Korsmeyer–Peppas model. The active PLA foams presented a higher potential of migration and faster release when compared with that reported in commonly used PLA films, showing that biopolymeric foams could be potentially used as active food packaging to improve the migration of active compounds with low migration potentials in order to improve their biological activity in foods.
Highlights
Introduction iationsThe concept of active packaging has emerged in the last few decades as an innovative strategy to increase the shelf-life and safety and enhance the sensory properties of minimally processed foods while preserving their quality
These density values were lower than the reported densities for Polylactic acid (PLA) foams obtained by chemical foaming [32] and by CO2 -assisted extrusion foaming [33], which was related to the obtaining of PLA foams with lower pore sizes
Representative scanning electron microscopy (SEM) images of the neat PLA foam, PLA nanocomposite foams with different concentrations of the nanoclay Cloisite® 30B nanoclay (C30B), as well the images of the impregnated PLA
Summary
Polylactic acid (PLA) 2003D (specific gravity 14 1.24; MFR g/10 min (210 ◦ C, 2.16 kg)). Was purchased from Natureworks® Co., (Minnetonka, MN, USA). Absolute ethanol and methanol (99.9% HPLC grade) were supplied by Merck (Darmstadt, Germany). Cinnamaldehyde (Ci) (≥99.5%) was purchased from Aldrich® Chemistry (St. Louis, MO, USA). The commercial organo-modified montmorillonite Cloisite® 30B nanoclay (C30B). (100 meq/100 g) was provided by Southern Clay Products (Austin, TX, USA). The C30B presented a plate-like geometry with typical particle sizes Carbon dioxide was supplied by Linde (Santiago, Chile)
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