Blends of chitosan (from Cuban lobster) and clay micro/nanoparticles were prepared by dispersion of the clay particles in the film matrix and the films obtained were characterized in terms of water solubility, water vapor, oxygen and carbon dioxide permeability, optical, mechanical and thermal properties using an Instron universal testing machine, differential scanning calorimetry, thermogravimetric analyses and scanning electron microscopy (SEM). The water vapor barrier properties of the films were significantly improved by incorporation of clay in their composition, while the water solubility decreased as the clay concentration increased (for a constant chitosan concentration). The tensile strength of chitosan/clay films increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. T m increased with the increase of chitosan concentration, but the changes in T m with the addition of clay were not significant. Polynomial models were fitted to the experimental data in order to facilitate future design of chitosan/ clay film systems.

This study aimed at determining the effect of chitosan coating on shelf life extension of salmon ( Salmo salar ) fillets. The success of edible coatings depends highly on their effective wetting capacity of the surfaces on which they are applied. In this context in a first stage the surface properties of salmon fillets and the wetting capacity of the coatings on fish were evaluated. In terms of wettability there were no significant differences (p > 0.05) between the solutions presenting higher values (solutions 1-4); therefore, solution 1 with a spreading coefficient (Ws) of -4.73 mN m(-1), was chosen to be subsequently analyzed and applied on fish fillets. For shelf life analyses the fillets were coated and stored at 0 °C for 18 days. The control and coated fish samples were analyzed periodically for total aerobic plate count (TPC), pH, total volatile base nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and ATP breakdown products (K value). The results showed that fish samples coated with chitosan presented a significant reduction (p < 0.05) for pH and K value after 6 days and for TVB, TMA, and TBA values after 9 days of storage, when compared to control samples. In terms of microbial growth, a slower increase in TPC was observed for the coated fish, indicating that chitosan-based coatings were effective in extending for an additional 3 days the shelf life of the salmon. These results demonstrate that chitosan-based coatings may be an alternative for extending the shelf life of salmon fillets during storage at 0 °C.

The objectives of this work were to determine the effects of the concentrations of glycerol and sorbitol (as hydrophilic plasticizers), Tween 80 (as surfactant) and chitosan on the wettability of Cuban chitosan-based edible coatings in view of their application on tomato and carrot and to develop a model allowing the optimization of coating composition.The values of the polar and dispersive components of the superficial tension of the foods were determined to be 3.04 and 25.67 mN/m, respectively, for tomato, and 0.34 and 26.13 mN/m, respectively, for carrot, the sum of the two components being the superficial tensions of tomato and carrot (28.71 and 26.48 mN/m, respectively). The skins of both foods are therefore low-energy surfaces, meaning that the Zisman method for the determination of wettability could be applied.The best experimental values of wettability were obtained for the following coating composition: 1.5% (w/v) of chitosan and 0.1% (w/w) of Tween 80.The increase in the concentration of chitosan and glycerol or sorbitol as plasticizers decreased the values of wettability and adhesion coefficients.The results of wettability were adjusted to a polynomial model that describes the dependence of the adhesion coefficient (W a ), cohesion coefficient (W c ) and spreading coefficient (W s ) on chitosan and Tween 80 concentrations. The optima calculated by the model equations were in excellent agreement (relative error below 3%) with the experimental values. r