Hydrolysis of the low gelatinization temperature Araucaria angustifolia pine seed starch

Abstract

Starch is the most abundant carbohydrate found in grains, roots and tubers. Modified starches are employed to overcome most of native starch limitations in industrial applications. Pinhao is the seed of Araucaria angustifolia and starch is approximately 36% of its composition. Acid hydrolysis changes the starch physicochemical properties without impairing the granular structure. The native and hydrochloric acid- modified (0.1 and 0.5 mol L−1) pinhao starches were investigated using thermal (TG-DTA and DSC), rheological (RVA), structural (XRD and SEM) and statistical analysis (ANOVA and Tukey). The aim of this study was to evaluate the effects of acid modification of pinhao starches in aqueous solutions. The starches were chosen because of their low gelatinization temperature (below 60 °C). TG-DTA results in air atmosphere showed that treated samples presented higher thermal stability. The same analysis using nitrogen atmosphere showed similarities between the samples. DSC results indicate that highest acid concentrations promoted crystallinity reduction and losses in the internal structure of the granule. The genetic sources demonstrated different behaviors. The viscosity parameters decreased with the intensity of acid treatment. The XRD identified the type C pattern for the starches and the relative crystallinity increased according to the intensity of the acid hydrolysis. Superficial changes in the granules were observed by SEM. Therefore, modified pinhao starch has potential use for industrial applications. Further studies are necessary to extend these applications.