Modificação por ultrassom e caracterização das propriedades termoanalíticas, físico-químicas e estruturais de amido orgânico da mandioquinha-salsa (arracacia xanthorrhiza)

Abstract

Starches are abundant carbohydrates in nature and serve as a source of energy. Due to its energetic and sensory properties, there is a growing interest in the possibilities inherent to its use within the food industries, especially in the functional aspects of resistant starch and its function in the formulation of foods with a lower glycemic index, a factor that contributes to the reduction of lipids and improvements in bowel function. The general objective of this study was to characterize the native starch of Arracacia Xanthorrhiza and the starches physically modified by ultrasound. And the specific objectives were: to extract, in aqueous medium, parsley starch; to investigate, from RVA viscoamylography, the influence of the modification in the paste profile of the treated samples and compare with the native starch; verify the stability and thermal decomposition of the native and modified samples, by thermogravimetric analysis, TG/DTG; obtain gelatinization curves of starch samples from differential scanning calorimetry, DSC; analyze and compare the morphology of starch granules before and after treatment, by scanning electron microscopy by field emission, FEG and determine the crystallinity profile of samples with and without modification, by X-ray diffraction. Methodology: physical treatment was performed of starch granules by ultrasound waves, using as variables for the analysis, different parameterizations of vibrational intensities (40%, 50%, 60% and 70%). Parsley persimmon (Arracacia Xanthorrhiza) was used as a botanical source for starch extraction. The extraction of starch from this vegetable was carried out using aqueous means and resulted in utilization rates close to those found in the bibliography. Enzymatic inactivation was performed by sodium metabisulfite. Analyzes were performed using viscoamylography (RVA), thermogravimetry (TG/DTG), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FEG) and X-ray diffraction. The results of the analyzes demonstrate that when treated with the correct vibrational intensities, the starches present less breakage (QV) and a tendency to retreat, suggesting good shear resistance (amplitude of 40%), higher values of peak viscosity and final viscosity (amplitude of 40%, 50%, 60% and 70%), greater tendency to retrogradation (range 40%, 50%, 60% and 70%), higher degradation temperature (range 50%) greater range of thermal stability (range 60%) , lower enthalpy of gelatinization (40% amplitude), greater increase in granular size (50% amplitude) and decrease in crystallinity (40%, 50%, 60% and 70% amplitude). Such changes demonstrate the great influence of ultrasound and its correct parameterization on the structure and thermal behavior of starches, which is a promising technology for modifying starch properties to achieve specific functionalities desired by food manufacturers.