RESEARCH ARTICLE Physical properties of biodegradable films from heat-moisture-treated rice flour and rice starch Mahsa Majzoobi 1 , Yasaman Pesaran 1 , Gholamreza Mesbahi 1 , Mohammad Taghi Golmakani 1 and Asgar Farahnaky 1,2 1 Department of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz, Iran 2 School of Biomedical Sciences, Graham Centre for Agricultural Innovation and ARC Industrial Transformation Training Centre for Functional Grains, Charles Sturt University, Wagga Wagga, NSW, Australia Native starch and flour are not successful in biodegradable film production. Heat moisture treatment (HMT) is a physical modification to improve functional properties of starch and flour, however, it is not fully understood if this method can enhance their film properties. This research, compares physical properties of biodegradable films produced from native rice flour (RF), rice starch (RS), and their heat-moisture-treated counterparts (HMTRF and HMTRS, respectively). Water solubility of the films reduced in the following order: RS film (23.91%) > RF film (19.77%) > HMTRS (19.50%) > HMTRF (16.22%). Water vapor permeability values of RF and RS films were 0.032 and 0.017 g mm m À2 h À1 KPa À1 which were increased to 0.043 and 0.027 g mm m À2 h À1 KPa À1 , respectively, after HMT. RF film was darker, more reddish, and yellowish but less transparent than RS film. HMT increased all the color parameters and further reduced the transparency of the films particularly for RF film. RS films had less flexibility, higher elongation at break, and tensile strength than RF films. HMT reduced films firmness, tensile strength, and resistance to stretch of both films. Overall, biodegradable films from HMTRF and HMTRS showed lower transparency, water solubility, rigidity, and extensibility while higher permeability to water vapor compared to their native counterparts. Received: April 21, 2015 Revised: July 14, 2015 Accepted: July 19, 2015 Keywords: Edible film / Heat moisture treatment / Rice flour / Rice starch 1 Introduction The negative effects of non-degradable waste materials on the environment and human health have been of great concern in recent years. Therefore, production of biode- gradable materials, particularly those suitable for food packaging is growing rapidly. Edible and biodegradable films are mainly used to preserve the quality of foods by preventing changes in taste, aroma, texture, and to extend the shelf-life. These materials are generally produced from polysaccharides and proteins obtained from different sources [1]. Starch is a natural and abundant polysaccharide which is frequently used in production of biodegradable and edible films. The physicochemical properties of edible films from different starch sources including potato, cassava and yam, corn, wheat, rice, and other sources have been studied previously [1–7]. The results have indicated that most of the films obtained from native starches have poor mechanical properties, gas permeability, and clarity. These shortcomings can be significantly improved by blending of starch with protein, polysaccharides, or addition of plasticizers [6, 8, 9]. Recently, the use of cereal flours in production of biodegradable films has attracted increasing attention because of the availability of the raw materials and the presence of a natural mixture of polysaccharides, proteins, and lipids which are usually used to improve the quality of Correspondence: Dr. Mahsa Majzoobi, Department of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz 7144165186, Iran E-mail: majzoobi@shirazu.ac.ir Fax: þ98-711-2286110 Abbreviations: HMT, heat moisture treatment; RF, rice flour; RS, rice starch; WVP, water vapor permeability DOI 10.1002/star.201500102 Starch/Stärke 2015, 67,1–8 1 ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.starch-journal.com