Enhancement of the functional properties of Dioscoreaceas native starches: Mixture as a green modification process

Highlights: •The modification shifted the thermal resistance of the native starches by ≅17 °C. •The enthalpy to gelatinise the native starches was considerably reduced. •The starch paste characteristics were improved by the mixture proportions utilised. -- Abstract: To study the effect of the mixing, three types of starch from Dioscorea sp., Dioscorea piperifolia Humb. var. Wild. and Dioscorea Trífida tubers were mixed in different proportions and their thermal, structural and rheological properties were characterised. Using thermogravimetric (TG) and differential thermal analysis (DTA) it was found that all the mixed samples presented enhanced thermal stability. By differential scanning calorimetry (DSC) and viscoamylograph (RVA) techniques it was verified that the amylose content from the D. sp. starch influenced the gelatinisation and paste properties of the mixed samples. Furthermore, using scanning electron micrograph (SEM) analysis it was possible to suggest a correlation between the size of the starch granules and their relative degree of crystallinity, which was calculated by the X-ray diffraction (XRD) patterns. The colour analysis revealed that, irrespective of the proportion, the strong tendency to yellow of the native Dioscorea piperifolia predominated in the mixed samples.