Effect of sucrose on the freeze–thaw stability of rice starch gels: Correlation with microstructure and freezable water

Rice starch gels subjected to repeated freezing and thawing tend to decrease in quality. This study investigated how the addition of sucrose to rice starch gels affects factors commonly used to measure quality. Rice starch gels containing 0–20% sucrose were treated to 5 freeze–thaw cycles. The result showed that sucrose effectively reduced the % syneresis. Scanning electron micrographs of freeze–thaw gels showed that smaller pore size and a thicker surrounding matrix corresponded with increasing sucrose concentration. Furthermore, the amount of freezable water in starch systems decreased with increasing sucrose concentrations, which also corresponded with gel microstructure. These results suggest that re-association of starch chains (retrogradation) induced by freeze–thaw treatment is retarded by sucrose. This study showed that sucrose is an effective agent for preserving the quality of freeze–thawed rice starch gels.