Ultrasound-Assisted Esterification of Andean Native Potato Starches Increases the Degree of Substitution and Reaction Efficiency

The esterification of starches with octenyl succinic anhydride (OSA) under alkaline conditions is a modification process that takes a long time. Ultrasound-assisted esterification was investigated as an alternative for obtaining esterified starches with higher degree of substitution (DS) and reaction efficiency (RE), which could have more possibilities of application. Andean native potato starches were subjected to a conventional esterification process (OSA) and esterification with ultrasound-assisted treatment (US-OSA). The morphological and size distribution of granules, molecular features (infrared spectroscopy and X-ray diffraction), thermal, and rheological characteristics were assessed. The DS and RE for US-OSA starches were higher than those for OSA ones. Modified starches showed some peeled granules with a few pores in their surfaces, and also, span values of US-OSA starches were lower than OSA ones. Molecular studies showed that both starches, OSA and US-OSA, did not exhibit notable differences. Enthalpy of gelatinization for US-OSA starches was lower than of OSA ones. Hence, the results suggest that the esterification process of starches can be facilitated with a green technology such as ultrasound-assisted treatment, which is fast-paced and does not change the esterified starch characteristics.