Polyphenols in sorghum seeds can slow down the breakdown of starch in rice flour. When sorghum extract is added to heated rice flour, the breakdown of amylose (a type of starch) is significantly slowed down compared to amylopectin. This slowdown is due to sorghum components binding to amylose. In suspendable starch, the breakdown of amylopectin is efficiently slowed down by the sorghum extract, possibly due to a complex formation with shorter amylose. This effect is not seen in glutinous rice flour, which is mostly amylopectin. The findings suggest that sorghum components can affect the breakdown of different types of starch in rice flour.