Caracterização físico-química, reológica, morfológica e térmica dos amidos de milho normal, ceroso e com alto teor de amilose Physicochemical, rheological, morphological, and thermal characterization of normal, waxy, and high amylose corn starches

The objective of this work was to evaluate normal, waxy, and high amylose corn starches from National Starch, through the determination of the physicochemical, morphological, thermal, and rheological properties. The high amylose corn starch (AM) presented amylose content of 71%, and the value of this component for the normal (M) and waxy (AP) corn starch was 27.8 and 1.8%, respectively. Traces of protein and lipids were observed in all samples. The waxy corn starch presented higher peak viscosity and lower tendency to retrogradation when compared with the normal corn starch. The (AP) starch presented the lowest gelatinization enthalpy. This can be observed in the DSC analysis, in which the gelatinization temperature obtained was 71 °C and the enthalpy was 3.34 J.g –1 . In the RVA analysis, the paste temperature was also equal to 71 °C. The retrogradation enthalpy of AP starch was 25.8% lower than the M starch. The AM starch presented a retrogradation enthalpy value equal to 26.38 J.g –1 validating the higher interaction of amylose molecule on the retrogradation process. This was also observed in the force of gels, in which the AM gel presented force 99.18% higher than other starches. The normal and waxy corn starches presented A X-ray diffraction pattern and the high amylose starch presented B X-ray diffraction pattern determined by X-ray diffraction analysis.