Tailoring soy protein film properties by selecting casting or compression as processing methods

Abstract This work describes how the manufacturing process selected to prepare soy protein films can affect both material properties and environmental impacts. Casting (wet process) and compression (dry process) were the processing methods employed, giving rise to films with different properties. In particular, the changes observed in thermal, optical, barrier and mechanical properties were related to the changes in the film structure and to the intermolecular forces involved during the film formation. On the one hand, casting films presented a higher hydrophobicity and water resistance and a lower yellowish colour. On the other hand, compression films were more transparent and had a smoother surface due to a higher degree of protein denaturation. Moreover, compression moulding allows less time-consuming manufacturing, which can be considered a benefit for industrial applications, but also for sustainability concerns. With this regard, life cycle assessment (LCA) was carried out in order to compare the two processing methods employed in this study due to the fact that the environmental aspects are an essential criterion for decision making when selecting materials and manufacturing processes.