Introduction An edible coating or film has been defined as a thin, continuous layer of edible materials, which may be eaten together with the food, formed or placed, on or between foods or food components. Their function is to provide a barrier to mass transfer (water, gas and lipids), to serve as a carrier of food ingredients and additives (pigments, flavours, etc.), or to provide mechanical and microbial protection. Water vapour adsorption data give the hydration properties of polymers. Thus, sorption isotherms (adsorption and desorption) of these films have been extensively studied [1–6] to investigate the moisture sorption behaviour of methyl cellulose films in order to evaluate some functional properties of films such as barrier property and stability of the films. The objective of this work is to produce and characterize cellulose-based films. For this purpose sodium carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) were used as the cellulose-based film forming materials. Films were characterized by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD). In addition, the water vapour sorption properties of the films were determined. Experimental Materials The film forming materials hydroxypropyl cellulose (HPC) (M w =370.000 g mol –1 ) and carboxymethyl cellulose sodium salt (NaCMC) (M w =250.000 g mol –1 ), used in this study, were supplied by Sigma-Aldrich. Glycerol was used as the plasticizer and was purchased from Merck. Deionized water was used as a solvent throughout the experiment. Film preparation To prepare films HPC or NaCMC (3, 4 or 5 g) were first dissolved in deionised water (100 cm 3 ) at room temper- ature by continuously stirring the solution for 4 h. After complete dissolution of film forming materials, glycerol was added as a plasticizer at 10% dry mass and the solu- tions were homogenized with a magnetic stirrer at room temperature for 1 h. Then, the solutions were kept in a vacuum oven at 25°C for about 48 h to remove airbub- bles or dissolved air. Finally, the solutions were spread on glass plates by using an automatic film applicator (Sheen Automatic Film Applicator 1133N). The spread films were dried at room temperature for 48 h, then at 60°C in an oven for 25 min. Finally they were detached from the glass plates, covered with paper and stored at room tem- perature. The thickness of the films were measured with a digital micrometer at ten different locations. Film thicknesses were approximately measured as 10, 20 and 30 mm for films prepared from solutions with 3, 4, 5 mass% polymer concentration, respectively. Methods Morphology of the films using SEM Each film was mounted on aluminum stubs using alu- minum sticky tape and coated with gold palladium film in a VG Microtech SC 7610 Sputter coater. Then, the specimen was examined using a Philips XL 30S FEG electron microscope. 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2008 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 683–686 SORPTION AND DIFFUSION OF WATER VAPOUR ON EDIBLE FILMS D. Berkün * , D. Balköse, F. TÏhmÏnlÏoÈlu and S. A. AltÏnkaya Izmir Institute of Technology, Department of Chemical Engineering, Gülbah ¸e Köyü, 35437 Urla-Izmir, Turkey Two types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were determined. The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore di- mensions of the NaCMC films. Keywords: cellulose films, diffusion, sorption, surface characterisation * Author for correspondence: didemberkun@iyte.edu.tr