Abstract
The physicochemical properties of sorghum determine its application. This study investigated the differences and relationships in the physicochemical properties of four typical japonica sorghum starches (JSS, including JZ159, JZ167, JZ169 and FZ4) and three waxy sorghum starches (WSS, including JN, LML and NL). The results showed that there were significant differences in their hydration properties, thermal properties, gelatinisation properties and digestibility. The water solubility index (WSI) of all starches was positively related to the swelling power (SP). With the increase in temperature (75-95 °C), the SP values of JSS and WSS samples increased significantly, and the SP of WSS samples was higher than that of JSS samples. Before 60 min, the digestibility of JZ159 and JZ167 was significantly lower. At 180 min of digestion, the digestibility of all starches was close (87.49-93.15%). At different temperatures, the SP and WSI values of WSS samples were significantly correlated with the predicted glycemic index (pGI), resistant starch (RS) and rapidly digestible starch (RDS), while the relationships among these parameters in JSS samples varied with temperature. This study also revealed the hydration characteristics of different sorghum starches and the influence of their hydration behaviours on physicochemical and digestive properties.