Synergistic effects of konjac glucomannan and curdlan on the qualities and starch digestibility of extruded gluten-free rice pasta

Konjac glucomannan (KGM, 6 %) and curdlan (CUD, 1-3 %) were mixed with rice flour to develop extruded rice pasta with improved qualities and reduced starch digestibility. Moreover, the underlying mechanisms were explored. When KGM and CUD were added, the pasting viscosities, the apparent viscosity, storage modulus (G'), loss modulus (G'') of rice flour increased, as did the hydrogen binding, short-range order and relative crystallinity of starch. In addition, the decrease in cooking loss and the increase in hardness, chewiness, springiness, cohesiveness and resilience were observed in rice pasta made from the rice flour-KGM-CUD mixture. Furthermore, the minimum estimated glycemic index (eGI) values of RP-RKC were achieved when CUD content was 3 %, which corresponded to the most compact and continuous network structure in its cross-section. These findings indicated that the incorporation of KGM and CUD into rice flour is a novel strategy for producing high-qualities and low-starch digestibility rice pasta.