Preparation of Antibacterial Cellulose Paper Using Layer-by-Layer Assembly for Cooked Beef Preservation at Ambient Temperature

Positively-charged epsilon-poly(L-lysine) (epsilon-PL) and negatively-charged carboxymethyl cellulose (CMC) were alternately deposited on a cellulose paper surface by the layer-by-layer (LBL) assembly technique. The formation of epsilon-PL/CMC multilayers was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), and zeta potential measurement. The morphologies of the multilayer-modified cellulose paper were observed by scanning electron microscopy (SEM). The epsilon-PL/CMC multilayers effectively improved not only the antibacterial activity of cellulose paper against both Escherichia coli and Staphylococcus aureus, but also the cellulose paper tensile strength property. Cellulose paper modified with a (epsilon-PL/CMC) 4.5 multilayer exhibited the strongest antibacterial activity, selected for preserving cooked beef for nine days at ambient temperature, could extend the shelf-life of beef for about three days compared with common commercial PE films. The prepared antibacterial paper did not show any evidence of the cytotoxic effect since it could not increase the cytoplasmic lactate dehydrogenase release from L-929 fibroblast cells in contact with the antibacterial paper, suggesting the possibility of utilization in food packaging field.