The antimicrobial properties of chitosan solutions and films against selected bacteria and the effect of chitosan incorporation into gelatin films were studied. The bactericidal effect of chitosan solutions increased with time and temperature of sample incubation. Two psychrotrophic strains Pseudomonas fluorescens and Listeria innocua were more sensitive to chitosan than mesophilic strains Escherichia coli and Staphylococcus aureus. The growth of bacteria under chitosan discs was inhibited. In the case of two component gelatin-chitosan films strong antimicrobial effect was also observed.

The aim of this work was to improve the mechanical and water barrier properties of composite films prepared from starch and clays, plasticized with glycerol at different concentrations. The effects of hydrophilic Closite Na þ and Nanomer PGV were compared with that exerted by organically modified more hydrophobic Nanofil 2 and NanoBent ZR-1. The antimicrobial activity of composites containing hydrophobic clays was also investigated. The hydrophilic Nanomer PGV at concentrations of 5-10% increased the tensile strength (TS) of unplasticized composites, but starch-Closite Na þ composites were too brittle to measure their mechanical properties. The hydrophobic clays did not improve the mechanical properties of the unplasticized composites. In the presence of glycerol at concentrations of 20-30%, TS of composites containing hydrophilic clays and even hydrophobic NanoBent ZR-1 increased in comparison to plasticized films without clay. None of the clays improved the water barrier properties of the unplasticized composites, while in the plasticized composites all the clays decreased the water vapor permeability to an extent dependent on the kind and concentration of clay and glycerol concentration. Starch-NanoBentZR-1 composite showed very high activity against gram-positive Staphylococcus aureus and Listeria innocua. StarchNanofil 2 composites were characterized by smaller activity. Neither composite showed any antimicrobial activity, or their activity against gram-negative bacteria was low.

No abstract

The aim of work was the improvement of the mechanical and water barrier properties of nanocomposites prepared from fish gelatin and nanoclays (5–15%), plasticized with glycerol at different concentrations. The effect of hydrophilic Cloisite Na+ and Nanomer®PGV was compared with that exerted by organically modified more hydrophobic Nanofil®2 and NanoBent ZR‐1. Antimicrobial activity of nanocomposites containing hydrophobic nanoclays was also investigated. In a nanocomposite with 5% Cloisite Na+ and 15% glycerol, the Tensile strength (TS) was by 20% higher than that for plasticized films without nanoclay. The improvement of TS was also evidenced for plasticized nanocomposites containing 5% of hydrophobic NanoBent ZR‐1 and Nanofil®2. Nanocomposites containing 5% of Cloisite Na+ with 15% glycerol, and these containing 5% Nanofil®2 or NanoBent ZR‐1 with 20% glycerol, showed 23% and about 15%, respectively, lower water vapor permeability than gelatin films. Gelatin‐NanoBent ZR‐1 nanocomposite caused complete inactivation of gram‐positive bacteria S. aureus and L. innocua. Practical applications The environmentally friendly food packaging materials based on natural polymers such as proteins and polysaccharides are promising alternative for nonbiodegradable, synthetic packages. The other advantage is using for the preparation of fish gelatin that can be obtained from fish industry offals, mainly skins—very burdensome for the environment. As packages based on natural polymers are most often edible, fish gelatin matrices are important for healthy and religious reasons. Incorporating fillers like some nanoclays into gelatin films can be a promising way for improving their mechanical strength and barrier properties against water. About 5% addition of hydrophilic Cloisite Na+ or 5% addition of hydrophobic NanoBent ZR‐1 increases tensile strength of gelatin films plasticized with 15% glycerol. Additionally, activity of NanoBent ZR‐1 against gram‐positive bacteria allow to obtain active packaging material that can be useful in extending the shelf life and keeping high quality of the food products.