Pasting, thermal and rheological properties of octenylsuccinylate modified starches from diverse small granule starches differing in amylose content

Waxy maize (a standard starch of normal granule size) and five small granule starches from different botanical sources (rice, wheat B type, oat, quinoa and amaranth) were subjected to 2-octenyl-1-succinic anhydride (OSA) modification. Changes of pasting, gel texture, thermal and rheological properties were investigated. Different small granule starches showed quite different property changes after OSA modification. Pasting viscosity was generally increased in OSA starches, among which OSA oat starch had notably high peak and breakdown viscosity but low setback viscosity. Gel hardness of rice, wheat B type, oat and quinoa starches was reduced by OSA treatment, whereas that of waxy maize and amaranth starches was increased. Amylose content was considered to be the major factor influencing pasting, gel and thermal property of OSA starches. Esterification increased pseudoplastic flow behavior of all starches, while OSA oat starch uniquely had reduced flow consistency coefficient. The dynamic rheological properties were also changed differentially among OSA starches. Viscoelastic properties of rice, wheat B type, oat and quinoa starches were increased after OSA treatment, whereas those of waxy maize and amaranth starches were decreased. This study showed that diverse functionalities from OSA small granule starches may fulfil different demands in product development.