Functional characterization of native starches through thermal and rheological analysis

Abstract

Native starch samples (corn, rice, and tapioca starches) were prepared in an aqueous slurry and dough system, and their functional properties were evaluated in terms of thermal and rheological characteristics. The pasting property results of starch slurries showed that rice starch exhibited the lowest peak temperature, whereas the highest peak viscosity was observed in tapioca starch. When starch suspensions were subjected to dynamic oscillatory temperature sweep testing, the increased storage moduli and reduced tan δ derived from starch gelatinization were clearly observed in all starch samples, showing that the gelatinized starch granules became more elastic. Steady shear measurements revealed the shear-thinning behaviors of starch pastes, which were dominant in tapioca starch, compared to the other starches. In addition, the distinct endothermic peaks of starch gelatinization were observed at 73.15, 62.25, and 70.55°C for corn, rice, and tapioca starches, respectively and these trends were in good agreement with the pasting and viscoelastic results. However, upon incorporation of the native starches to a wheat dough system, the highest dough consistency during heating and cooling was observed in corn starch probably due to the rigidity of its particle. Thus, the physicochemical response of native starches to temperature appeared to be different in different concentration regimes.