Improvement in quality deterioration of frozen cooked rice during freeze-thaw cycles: Antifreeze protective effect of inulin addition

Frozen cooked rice undergoes multiple freeze-thaw cycles (FTC) during production-transport-marketing process, resulting in significant quality deterioration. Therefore, developing effective strategies to improve frozen cooked rice freeze-thaw stability is crucial. This study innovatively introduced a natural cryoprotectant, inulin (1-3 g/100 g raw rice). It significantly improved the freeze-thaw stability of medium-chain triglyceride and tea polyphenol fortified cooked rice (MCT-TP-FCR) by inhibiting water migration and maintaining the hydrogen bond network of starch molecules. The hydrophilic groups (-OH) of inulin formed hydrogen bonds with combined water molecules in MCT-TP-FCR, enhancing water-binding capacity while inhibiting water migration and ice crystal formation/growth. Consequently, the freezable water content decreased significantly from 83.23% to 61.00%. Simultaneously, inulin formed hydrogen bonds with starch molecules, preserving its short-range order and microstructural integrity during FTC. Additionally, inulin retarded the decline in hardness and chewiness of MCT-TP-FCR, reduced polyphenol loss by 4.81%, and increased the contents of volatile esters (especially butyl propionate content increased by 27.19%), thus significantly improving the textural profile, antioxidant properties and enhancing its flavor characteristics. Therefore, inulin is an effective cryoprotectant that significantly inhibits the quality deterioration of MCT-TP-FCR during FTC, improving the freeze-thaw stability of frozen cooked rice. • Inulin improved the quality deterioration of medium-chain triglyceride and tea polyphenol fortified cooked rice (MCT-TP-FCR). • Inulin binds water/starch molecules in MCT-TP-FCR via hydrogen bonds. • Inulin significantly decreased the freezable water content from 83.23% to 61.00%. • Inulin reduced polyphenol loss of MCT-TP-FCR by 4.81% during FTC. • Inulin significantly increased ester content, enhancing aroma of MCT-TP-FCR.