Emprego de técnicas e termoanalíticas na análise de amidos nativos e modificados de mandioca

Abstract

Starch is an abundant carbohydrate in nature, can be extracted from several botanical sources and has many industrial applications, mainly in the food sector.Due to some limitations of native starch, the production of modified starch has been an alternative to overcome these restrictions and promote increase in use of this polymer. This study used techniques thermoanalitycal TG, DTA and DSC for the evaluation of thermal properties (stability, gelatinization and enthalpy). Also has been applied optical microscopy and X-ray diffraction in samples of native cassava starch, extracted in laboratory and commercial sample wich were modified by action of H2O2 in different concentrations (1, 2 and 3%) with and without addition of the catalyst FeSO4 (0,01%). The results of thermal analysis showed that the onset temperature (To) and peak (Tp), and enthalpy of gelatinization (ΔHgel) vary with the degree of oxidation. The native starch granules showed characteristic morphology and only showed small changes in morphology after treatment with H2O2 in the concentration of 3%. Through X-ray diffraction can be seen the typical crystallinity of starches and were observed few changes in the patterns of crystallinity of the modified starches.