Biodegradable foam tray based on starches isolated from different Peruvian species

Starch was isolated from three Andean-native crops — arracacha (Arracacia xanthorrhiza), oca (Oxalis tuberosa), and sweet potato (Ipomoea batatas) — for use as a raw material for the production of foam trays. The starches were characterized in their proximal composition, crystallinity, microstructure and thermal properties. The sweet potato starch showed the highest amylose content (42.65%) and the lowest protein content (0.30%). The oca starch granules were larger (10–30 μm) than sweet potato and arracacha starch. The highest crystallinity of sweet potato starch caused larger values of onset temperature (To), peak temperature (Tp), conclusion temperature (Tc) (67.64 °C, 72.83 °C, and 81.20 °C, respectively) than arracacha and oca starch. The novel foam trays showed good appearance, adequate expansion, and low density; however, all foam trays showed a water absorption capacity >50%, which was related to their porosity and low density. Also, sweet potato and oca starch trays showed high tensile strength (0.67 and 0.65 MPa, respectively) compared with arracacha starch trays (0.52 MPa).