Effects of amylose and resistant starch on glycaemic index of rice noodles

Rice is generally high in glycaemic index (GI). Amylose and resistant starch (RS) play an important role in controlling the GI. The levels of amylose and RS in the mixed flours for rice noodle production (rice flours mixed with tapioca starch) were manipulated by adding high amylose maize starch. This resulted in the increase of amylose and RS from 32 to 50 and 0.4 to 16 g/100 g dry sample respectively. The mixed flour samples were used to produce rice noodles. Their GI values were estimated by an in-vitro enzymatic digestion assay and confirmed by an in-vivo method. It was found that the GI of rice noodles decreased as amylose and RS increased. However, high amylose and RS affected the texture as they reduced the tensile strength of the noodles.