Impact of treatment with HCL/alcoholic in the modification of corn starch

Abstract

The physical, chemical, or enzymatic modified starches are well suited for industrial applications. Acid hydrolysis changes the physicochemical properties without impairing the granular structure of starch. The acid hydrolysis in alcoholic solution can recover the granule starches after modification. Starch, the most abundant carbohydrate in grains, roots and tubers, is composed by amylose and amylopectin. Corn starch represents 85% of the global starch market. The aim of this study was to evaluate the effects of soft acid, acid–ethanol and acid methanol solutions, considering its application in the paper industry. One sample remained as native. The other six samples were modified with acid, acid–ethanol and acid–methanol solutions, at concentrations of 0.1 and 0.5 mol L−1 (hydrochloric acid). The acid treatment changed the thermal (TG) and rheological (RVA) properties of the corn starch. The TG/DTG results showed shifted (up to 8 °C) stability temperature ranges for the samples treated with a higher concentration of HCl in ethanol and methanol solutions. The RVA results for final viscosity of the treated samples showed an intense reduction of 1405 cP related to the native sample. DSC curves demonstrated that the treatments slightly modified the gelatinization behavior of the starch. The micrographs showed small changes in granules average diameter size after the modification process. Acid hydrolysis did not change the crystalline pattern of corn starch, and its relative crystallinity was slightly affected. According to the results obtained for the acid/alcohol, modified starches present suitable properties for their application in the paper industry.