RESUMO
Functional modifications of starch, such as paste properties, retrogradation, water absorption indexes, solubility, and swelling capacity, are induced by the amylose-lipid complex. This research comprehends the study of functional properties of extruded maize starch mixed with fatty acids (stearic acid, oleic acid, and maize oil) and the formation of amylose-lipid complexes. Maize starch with lipids (5 or 10 %), moisture (35 %) was extruded (single screw). Starch granule was modified by extrusion, to a lesser extent at 10 % of lipids, especially stearic acid, which covers starch granule surface. Viscosity decreased meaningfully with stearic acid addition. DSC showed both starch gelatinization enthalpy and amylose-lipid complex enthalpy for stearic or oleic acid, but it was just the first enthalpy for maize oil. X-ray diffraction showed orthorhombic crystals with or without the presence of lipids. Our results indicated that stearic acid yielded the highest amount of amylose-lipid complexes.
Assuntos
Amilose/química , Lipídeos/química , Ácido Oleico/química , Extratos Vegetais/química , Ácidos Esteáricos/química , Zea mays/química , Varredura Diferencial de Calorimetria , Cristalização , Temperatura Alta , Solubilidade , Viscosidade , Água/química , Difração de Raios XRESUMO
Sorghum (Sorghum bicolor L. Moench) has been sparsely used as human food due to certain anti-nutritional factors such as tannins that reduce its digestibility, although the grain is an important source of bioactive compounds such as phenolic compounds (PCs). This study aimed to assess the impact of cooking and alkaline cooking (nixtamalization) on the bioaccessibility and antioxidant capacity of PCs of two sorghum varieties (white/red). Nixtamalization was the most effective procedure for the reduction of tannins (74.3%). Gallic acid proved to be the most bioaccessible PC (6359⯵g/g). The total phenolics and condensed tannins correlated with the antioxidant capacity (ABTS/DPPH; R2: 0.30-0.43, pâ¯<â¯0.05). These results confirm the potential of thermal procedures to significantly modify the bioaccessibility of sorghum compounds, enhancing their concentrations and reducing anti-nutritional factors (tannins) while improving their antioxidant capacity.