Effects of amylose content on the paste properties and emulsification of octenyl succinic starch esters

Octenyl succinic starch esters were prepared from 12 strains of native indica rice starches with AM contents (AC) of 1.6527.15%. The paste properties and emulsification were also investigated to evaluate the effect of ACs on starch properties. Results indicated that the degree of substitution for octenyl succinic starch ester were 0.02120.0252. Rapid visco analyzer (RVA) parameters demonstrated that octenyl succinic starch esters had higher relative viscosities than the native counterparts. Moreover, AC correlated negatively with the major RVA parameters (e.g. peak viscosity and breakdown viscosity). Compared with the native starches, octenyl succinic starch esters had higher paste clarity, decreased retrogradation, better freezethaw stability, and excellent gel texture, depending on ACs of the native starches. SEM showed that the gels from octenyl succinic starch esters had less and smaller pores, however, the gels from native starches changed to sponge-like structure after three freezing/thawing cycles. Fluorescence photomicrographs and droplet size distribution indicated that octenyl succinic starch ester was an effective emulsifier for oil-in-water emulsions. This type of modified rice starch can potentially be employed as a thickener and emulsifier in frozen foods.