Processing and characterization of starch-based materials from pehuen seeds (Araucaria araucana (Mol) K. Koch)

Starch isolated from pehuen seed (Araucaria araucana (Mol) K. Koch) was employed for producing thermoplastic starch (TPS). Pehuen starch was characterized, stating that the granules are rounded and small (12–21 μm), with an amylose content range 38–40%, a crystalline C-type structure and thermally stable, with decomposition temperature above 300 °C.The effect of plasticizer type (glycerol and sorbitol) and starch/plasticizer ratio on TPS properties was also investigated. X-ray diffraction patterns of TPS showed the formation of processing-induced crystallinity, which depended on plasticizer employed. Thus, glycerol plasticized TPS presented the VH-type structure, while sorbitol plasticized TPS presented the EH-type structure. Sorbitol plasticized TPS had a higher thermal stability than glycerol plasticized TPS. Sorbitol plasticized TPS provided a material with more brittles and less flexibility. In contrast, glycerol plasticized TPS was tough and ductile. The tensile strength of TPS decreased with the increase in plasticizer content.

► Pehuen starch from Araucaria araucana was used to obtain thermoplastic starch (TPS).
► Pehuen starch had crystalline C-type structure and high thermal stability.
► Mechanical/thermal properties of TPS depend on starch/plasticizer ratio.
► Glycerol plasticized TPS are though and ductile.