Physicochemical and morphological characteristics of nixtamalized maize starch

The effect of nixtamalization on physicochemical and morphological characteristics of starch was studied. Determination of total starch, ash and amylose content, of swelling and solubility, gelatinization characteristics and morphological studies were carried out in starch isolated from native (S) and nixtamalized (NS) maize flours. Thermal analysis showed that nixtamalization produced starch annealing due to the higher gelatinization temperature obtained for NS. However, S had slightly lower enthalpy values. The swelling profile was similar for both starches, but the solubility values at the temperatures assessed were slightly higher in the NS samples. At temperatures below gelatinization, the granules showed the Maltese cross while at higher temperatures only ghost of granules were observed. The nixtamalized starch had larger granule sizes than the native starch, due to the partial swelling produced in the heating during the nixtamalization process. Larger granule sizes were also observed by image analysis, because major axis and area parameters were higher in NS samples than in S samples. The nixtamalization process produced changes in chemical, thermal and morphological characteristics, becoming important in products obtained from nixtamalized maize.