Low-starch potato peel for the development of starch-based composites obtained by thermocompression moulding

Abstract

In this study, the effect of incorporating low-starch potato peel, whether thermally treated or not, into starch-based films on their functional properties was evaluated. The films, obtained by melt blending and thermo-compression moulding, were characterised in terms of barrier, thermal and optical properties together with the microstructure, FTIR analysis and antioxidant activity. The potato peel particles subjected to the thermal pre-treatment exhibited a more homogeneous size distribution and increased phenolic content. The incorporation of potato peel into the starch matrix led to films that were mechanically more reinforced as compared to the neat starch films (up to 233% and up to 448% higher tensile strength and elastic modulus, respectively) with improved water vapor barrier capacity (up to 30%). In general, these improvements were slightly greater in films incorporating the thermally pre-treated potato peel, likely because these films presented a better integration of the residue components into the polymeric matrix. Furthermore, the composite films presented strong light barrier capacity and exhibited notable antioxidant activity, which could be of interest to limit oxidative processes in oxidation-sensitive foods. Thus, these results showed that it is possible to obtain films with up to 50 g/100 g starch (or 27 g/100 g film) of low-starch potato peel with enhanced properties at a lower cost.