Modulation of starch-based film properties for potential application as coating systems

Starch-based coating systems find application in different industrial sectors as eco-friendly carriers of bioactive compounds such as in fertilizers and seeds. However, starch cannot be used as the only matrix component because of its high hygroscopicity and poor mechanical qualities. Here, we investigated the effects of the sequential addition of maltodextrin, cellulose, glycerol, and bentonite on the physicochemical characteristics of starch-based films potentially applied in coating systems. It observed that the addition of bentonite tends to increase hydrophobicity, but association with glycerol contributed to its reduction. The sequential reduction in water vapor permeability was observed, achieving lower values with the addition of bentonite. Viscosity variation was also verified, still in gel form. The matrices with or without glycerol showed a significant increase in viscosity with the addition of bentonite. The adjustment of this parameter is essential in the coating system. This trend is also observed for mechanical properties. In this case, cellulose addition provided a remarkable variation. Additionally, the water content between the starch chains is considerably reduced, as well as the brittleness and uniformity are improved with the simultaneous addition of fillers and glycerol-containing matrices.