Improvement in freeze-thaw stability of rice starch gel by inulin and its mechanism

•Inulin improved the freeze-thaw stability of rice starch gel.•Inulin with lower DP was more effective for improving the freeze-thaw stability.•Inulin bound water and reduced the amount of freezable water of the gel.•Retrogradation of the gel during freeze-thaw cycles was retarded by adding inulin. Three types of inulin with different degree of polymerization (average DP 23) were used to improve the freeze-thaw stability of rice starch gel. The gels with or without addition of inulin were subjected to seven freeze-thaw cycles (FTC). Inulin enhanced the water holding capacity and reduced the amount of freezable water of the gels, thereby decreasing the syneresis of the gels during seven FTC. In addition, the amylose and amylopectin retrogradation of the gels were retarded. By adding inulin, the microstructure of gel network was stabilized, and the deterioration in viscoelastic properties of the gels during seven FTC was reversed. Therefore, inulin was an effective additive for preserving the quality of freeze-thawed rice starch gels. Furthermore, low DP inulin had higher water holding capacity than high DP one, as a result the inulin with lower DP was more effective.