Effects of gums on physical properties, microstructure and starch digestibility of dried-natural fermented rice noodles

The effects of gums including carboxymethyl cellulose (CMC), xanthan gum (XG) and guar gum (GG) on physical properties, microstructure and starch digestibility of dried-natural fermented rice noodles were investigated. The gums, each at 0.05 and 0.10 g/100 g wet basis, were added to the flour during rice noodle production. Control was the sample without the addition of gums. Physical properties (color, water absorption, cooking loss and firmness), microstructure, starch composition and in vitro starch digestibility were determined. Generally, the addition of gums improved the physical qualities of rehydrated fermented rice noodles as evidenced by high water absorption and low cooking loss. CMC provided the best result for improvement of the physical properties of rice noodles. The addition of gums promoted the porous microstructure in rice noodles. In terms of starch digestibility, the addition of gums increased the rate of starch digestion and consequently provided high estimated glycemic index (GI). Samples with XG showed the highest starch digestion rate and estimated GI values when compared with CMC and GG. It is concluded that CMC, XG and GG improved the texture and cooking quality of dried-natural fermented rice noodles but they had negative effects on starch digestion rate and estimated GI.