Scale-up of the production of soy (Glycine max L.) protein films using tape casting: Formulation of film-forming suspension and drying conditions

The processing variables used to produce biopolymer films may have great influence on the material's properties and production time. The aim of this work was to determine i) a suitable formulation (concentration and rheological properties) for tape casting processing of soy protein suspensions ii) the effects of the drying method (heat conduction, C; and infrared radiation, IR) and temperature (40, 50 and 60 degrees C) on the drying kinetics and physical properties of resulting films. A soy protein isolate (SPI) concentration over 10.5% w/v was required for proper tape casting processing. Conduction drying at 60 degrees C (C-60) and IR60 showed short drying times and similar drying kinetics. However, drying by IR60 yielded films having poor mechanical properties. Raising the drying temperature increased film's tensile strength, Young's modulus, glass transition temperature (Tg), and heat seal strength. The results of this study demonstrated that it is possible to produce soy protein films at large scale by tape casting. The influence of the processing method and drying conditions on soy protein film properties are discussed. (C) 2016 Elsevier Ltd. All rights reserved.