Designing of a wheat gluten/montmorillonite based system as carvacrol carrier: Rheological and structural properties

E-mail [email protected] audienceAn antimicrobial delivery system was designed from film-forming solutions containing wheat gluten 20% (wt/vol) (WG) as matrix, montmorillonites (Mmt) as structuring agent and carvacrol as active agent (15% wt/wt dry WG). The objectives of this work were to understand how the addition of montmorillonites (0-10% wt/wt dry WG) affects the carvacrol retention capacity of both the film forming solution and the resulting film obtained by casting. For this purpose, structural, granulometric and rheological changes that occurred in the film-forming solutions were studied. The introduction of carvacrol in a WG solution containing increasing amounts of Mmt resulted in dramatic changes in its rheological behaviour. Depending on the Mmt amount added (=5%), the viscosity evolved in different ways indicating an unexpected and specific effect of Mmt on the WG solutions that contain carvacrol. In the presence of a sufficiently high Mmt content (>=5%), particles size measurements and microscopic observations pointed out large aggregated structures. These aggregated structures were supposed to result in an entrapment of carvacrol molecules that could be responsible for a higher carvacrol retention exhibited by both WG film-forming solutions and cast films. Further indications of this assumption were provided by XRD measurements that confirmed the establishment of specific interactions between Mmt, carvacrol and WG. The investigated delivery system based on a WG matrix reinforced by high content of Mmt fillers (>=5%) was clearly efficient to retain and protect an antimicrobial active agent such as carvacrol during the processing stag

Diffusivity of propolis compounds in Polylactic acid polymer for the development of anti-microbial packaging films

Correspondance: [email protected] audienceA major research gap is the lack of packaging materials that can provide the release of active compounds at rates suitable for a wide range of food packaging applications. For this reason an anti-microbial/antioxidant release system for food packaging applications was realized by incorporation of propolis into Polylactic acid (PLA) film. The composition of the films was modified by adding polyethylene glycol (PEG) and calcium bentonite (CB) to the initial PIA casting solution; dispersed structures in fact open the molecular network and increase migration rates. The presence of the anti-microbial compound is required essentially at the food surface where the microorganisms are numerous and where they are intended to grow. The diffusivity of four polyphenols was measured in water and ethanol as food simulating liquids (FSL) and the concentration of additives at the interface PLA/Food Simulant was calculated using Fickian models. The external mass transfer coefficient at the interface polymer/FSL could be neglected (with Bi number higher than 200). This is due to the low diffusivity values of propolis polyphenols in the PLA matrix (0.03-0.83 x 10-13 m(2)/s) which lead to a predominant internal mass transfer phenomenon compared to the external one in the system PLA/water. The concentration at interface at equilibrium was different for each substance and depended of the thermodynamical parameter K. Such a delivery system for direct contact with liquid aqueous medium would be a very efficient delivery system because some active agents (polyphenols acids) would be released in relevant quantity in the food whereas others (flavonoids) would remain in the polymer to act at the polymer/food interfac

Anti-microbial effectiveness of relative humidity-controlled carvacrol release from wheat gluten/montmorillonite coated papers

International audienceWheat gluten coated papers containing carvacrol (15wt%) as anti-microbial agent and montmorillonite (0-7wt%) as filler were investigated as anti-microbial controlled delivery systems. The carvacrol losses were followed during the coating process and storage time at 30 infinity C under controlled RH from 40 to 100% RH. Increasing MMT content limited carvacrol losses during the coating process. A mathematical model based on Fick's second law was used to determine the apparent diffusivities of carvacrol from experimental data of kinetic release at 30 infinity C and controlled RH. Diffusivity values varied from 0.143 x 10(-14) m(2)/s (0wt% MMT, 40% RH) to 6.010 x 10(-14) m(2)/s (5wt% MMT, 100%RH) depending on both MMT% and RH. The carvacrol diffusivities increased with increasing RH, and the presence of a high amount of MMT(>= 5wt%) accentuated the RH-induced effect. Specific aggregated structure was evidenced by SEM and TEM in the presence of carvacrol and 5wt% MMT creating a preferential pathway for carvacrol diffusion. The anti-microbial efficiency of the MMT-WG-coated papers toward Escherichia Coil was assessed and showed that the antimicrobial effect was related to the carvacrol diffusivity. The diffusivity coefficients were utilized to optimize the packaging characteristics required to develop an efficient anti-microbial system and were finally validated against Botrytis cinerea

Nanoparticles/aroma compound/protein complexes for antimicrobial coating applications

International audienc

Nanoparticles/aroma compound/protein complexes for antimicrobial coating applications

International audienc