PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2009; 22: 161–170 Published online 21 November 2008 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/pts.839 Chitosan Tailor-Made Films: The Effects of Additives on Barrier and Mechanical Properties By Cristiana M. P. Yoshida,* Enio Nazaré Oliveira Junior and Telma Teixeira Franco School of Chemical Engineering, State University of Campinas, PO Box 6066, 13083-970, Campinas, São Paulo, Brazil With the aim of achieving ‘tailor-made’ chitosan films, the effects of several variables on the properties of chitosan films were studied. These variables were chitosan concentration and molecular weight of thermally depolymerized chitosan, addition of lipids (palmitic acid, beeswax or carnauba wax) and plasticizer (glycerol). The water vapour transmission rate (WVTR) and mechanical properties of these films were measured. The innovative feature of this study is that it provides specific information to support the design of tailor-made films. These can only be formulated when the effects of the important variables are well understood. It was found that WVTR was reduced by 57% in film made from chitosan that had been thermally treated for 7 h at 100°C (molecular mass 13.7 kDa), while in the emulsion films, the WVTR was increased by incorporation of palmitic acid, beeswax or carnauba wax incorporation. The mechanical properties (tensile strength and elongation at break) were improved when glycerol was used as plasticizer, resulting in more elastic films (increasing the elongation at break by 62%). Copyright © 2008 John Wiley & Sons, Ltd. Received 26 February 2008; Revised 6 October 2008; Accepted 10 October 2008 KEY WORDS: chitosan; plasticizer; lipid incorporation; water vapour transmission rate; mechanical properties; thermal depolymerization * Correspondence to: Cristiana M. P. Yoshida, School of Chemical Engineering, State University of Campinas, PO Box 6066, 13083-970 Campinas, São Paulo, Brazil. E-mail: kity@feq.unicamp.br Copyright © 2008 John Wiley & Sons, Ltd. INTRODUCTION Biodegradable packaging films continue to be important food and pharmaceutical research targets, owing to the very significant potential commercial applications. 1 The interest in edible biodegradable packaging has been increasing, owing to several advantages. 2 Polysaccharides, proteins and lipids constitute a group of biomateri- als that readily form biofilms. 2,3 Natural polymer films have been investigated for their ability to retard the transport of moisture, gases, flavour and lipids. The treatment of natural polymers to improve their barrier and mechanical properties is important in food systems to prolong the shelf life of food products. 4 Chitosan is a polysaccharide derived from chitin by removing acetyl groups with alkali. Chitin is very abundant in nature, being found in fungal walls and exoskeletons of crustaceans and insects. 5 Chitosan is an excellent film-forming linear polymer with a backbone consisting of β-(1–4)-