Sodium alginate/carboxymethyl cellulose films containing pyrogallic acid: physical and antibacterial properties

BACKGROUND Antibacterial films were prepared using sodium alginate ( SA ) and carboxymethyl cellulose ( CMC ) as a matrix, glycerin as a plasticizer and CaCl 2 as a cross‐linking agent, and by incorporating the natural antibacterial agent pyrogallic acid ( PA ). The present study describes the microstructure and the physical, barrier, mechanical, optical and antibacterial properties of blended films prepared by incorporating different concentrations of PA into the SA / CMC matrix. RESULTS The microstructure of the films was investigated by Fourier transform infrared spectroscopy and scanning electron microscopy, which revealed that PA interacts with the SA / CMC matrix through hydrogen bonding. Moreover, the incorporation of PA increased the moisture content, water vapor permeability and oxygen permeability of SA / CMC films. Films containing 40 g kg −1 of PA had the highest elongation at break result (39.60%). Compared with pure SA / CMC films, the incorporation of PA improved the barrier properties against ultraviolet light; however, it decreased the color parameter L * value and increased the a * and b * values of the films. Furthermore, films with PA , especially at higher concentrations, were more effective against Escherichia coli and Staphylococcus aureus . CONCLUSION Antibacterial SA / CMC films incorporating PA appear to have good potential to enhance the safety of foods and food products. © 2016 Society of Chemical Industry