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Effect of Amylose Content on Expansion of Extruded Rice Pellet

¹Graduate Institute of Food Science and Technology, National Taiwan University. ²Corresponding author. E-mail: yehs@ccms.ntu.edu.tw Phone: +886-2-2363-3148. Fax: +886-2-2362-0849.

Rice pellets were prepared by single-screw extrusion cooking with an in-barrel water content of 50 wt%. Three different types of rice, indica glutinous, japonica, and indica, were used as raw materials. Reconstituted rice flour was made to study the effect of amylose content on pellet expansion. The glass transition (T_g) and expansion (T_e) temperatures of extruded pellet were determined by differential scanning calorimetry (DSC) and noncontact infrared thermometer, respectively. The amylose content was not significantly affected by extrusion cooking. The reduction in intrinsic viscosity indicated that amylopectin experienced some degradation. The T_g and T_e were not functions of amylose content, which affected the expansion ratio of the pellets. The Gordon-Taylor equation was applied to estimate the T_g of the rice pellets.