Fat resistance properties of chitosan-based paper packaging for food applications

The objective of this study was to potentially replace fluorocarbon-treatment of paper-based materials by chitosan coating to produce oil barrier packaging. With this work, the nature of interactions existing between fatty acids, chosen as model lipids (such as oleic acid, largely present in the food field), and chitosan was particularly investigated. The influence of the fatty acid content and the effect of pH were studied. The ability of chitosan to interact with lipid was shown to be pH sensitive. In acidic conditions, the polycationic chitosan exhibited a stabilization of the fatty acid emulsion, which was attributed to its capacity to bind with anionic lipid molecules, as suggested by the sudden change in residual free oleic acid concentration with a slight shift in pH. Since calcium adsorption from foodstuff is known to decrease the nutritional value of the product and since chitosan exhibits chelating properties, interaction between chitosan and calcium was concurrently investigated. Whatever the pH used, adsorption of Ca2+ ions by chitosan was found to be minor. The fat barrier properties of paper and chitosan-coated paper were also compared in application tests. It was concluded that chitosan coating could be used as fat barrier but treatment cost remained high compared with fluorinated resins. In an attempt to decrease both treatment cost and fat transfer, other natural molecules such as cellulose ethers and alginates were included with chitosan, in the coating formulations. Alginates were found to give the best results. (C) 2005 Elsevier Ltd. All rights reserved.