Abstract: This study investigated the effects of different concentrations of inulin (1%, 2%, 3%, 4%, and 5%) on the quality characteristics of frozen Zongzi after freeze-thaw cycles. The regulatory effects of inulin on the freezing rate, water loss rate, water distribution, freezable water content, starch aging, texture characteristics, sensory evaluation, and microscopic structure of frozen Zongzi were evaluated. The results showed that freeze-thaw treatment increased the water loss rate of frozen Zongzi, promoted outward water migration, and increased the freezable water content. It also significantly promoted starch aging and increased the hardness and chewiness of frozen Zongzi. Meanwhile, the microstructure of glutinous rice developed a honeycomb-like pattern, and the overall sensory score decreased. In contrast, adding inulin effectively delayed the deterioration process and this effect significantly increased with increasing its concentration (1%–5%). When the inulin concentration was 5%, the freezing rate significantly increased. Compared with the frozen-thawed group without inulin, the water loss rate of frozen Zongzi decreased, the tightly bound water content increased by 1.18%, the freezable water content significantly decreased by 9.69%, the relative crystallinity of starch decreased by 3.39%, and the R1 047/1 022 value decreased by 0.021. At the same time, the hardness and chewiness decreased significantly, the numbers of pores and cracks in the microscopic structure of glutinous rice significantly fell, and the comprehensive sensory score was closer to that of the non-frozen-thawed group. In conclusion, freeze-thaw cycles led to starch aging and ice recrystallization, significantly affecting the taste and quality of frozen Zongzi. Adding inulin could effectively delay quality deterioration. This study provides a theoretical basis for the application of inulin in quick-frozen glutinous rice products and the industrial production of frozen Zongzi.

Key words: frozen Zongzi; inulin; freeze-thaw cycle; quality characteristics