Effect of High Hydrostatic Pressure, alkaline and combined treatments on corn starch granules metal binding: Structure, swelling behavior and thermal properties assessment

Modification of corn starch granules to transform them into carriers for molecules of nutritional interest was assayed by alkaline and high pressure treatments. Changes in the granular structure of starches were revealed by porosimetry and swelling power studies, while confocal microscopy evaluated the mode of disruption of the granules. Both alkali and high pressure treatments increased the number of pores in the granules while the combined procedures led to a central disruption and an increased deep pore number. The high pore volume found in alkali treated starches resulted in a high swelling power and created more binding sites to load high amounts of minerals, such as zinc and magnesium, as determined by atomic emission spectrometry. The extent of gelatinization process was affected differently in treated starches. The reduction in temperature and enthalpy, associated to high pressure granular starch suspensions, was moderated by the creation of new charged interactions due to alkali addition.