OSA Esterification of Amaranth and Maize Starch Nanocrystals and Their Use in “Pickering” Emulsions

Emulsions are widely used in food, drug, and cosmetic products. Due to their small size, starch nanocrystals are proposed to stabilize Pickering emulsions. However, this application is effective only when starch nanocrystals offer a strong amphipathic character. Waxy maize and amaranth starch nanocrystals are treated chemically with octenyl succinic acid (OSA) to obtain particles which are able to stabilize of oil-in-water emulsions. The emulsification capacity of OSA-treated starch nanocrystals is compared with the capacity offered by non-treated starch. It is shown that OSA treatment enhanced the emulsification capacity, and the effect is attributed to the increase of repulsive forces as reflected by ζ-potential. Compared with nanocrystals obtained from waxy maize starch, amaranth exhibits superior emulsification ability, which is preserved under storage conditions. Overall, the results show that OSA-treated starch nanocrystals are viable alternatives for the stabilization of emulsion systems.