Combining ozone and ultrasound technologies to modify maize starch.

In this work, maize starch was modified using ultrasound (US) and ozone (O) treatments, each one alone and also in combination. The starch molecular structure, granule characteristics and properties were evaluated. The US treatment alone did not show influence on the starch physical characteristics. On the other hand, the O treatment, alone or in combination with US, led to significant changes on starch molecules by increasing carbonyl and carboxyl groups and the apparent amylose content, while decreasing pH and the starch molecular size distribution. The granules' particle size distribution (PSD), their morphology and crystallinity were not affected by any of the treatments. Regarding the starch properties, water absorption index (WAI), water solubility index (WSI), pasting properties and gel strength were clearly more affected by the ozone treatment as compared with the ultrasound treatment. However, the paste clarity was significant higher when the combined treatments were applied, especially when US was used before O. These results are prompting the hypothesis that the US treatment improved the subsequent action of O.