Carbon Dots as Antifreeze Agents: Impact on the freeze-thaw stability, Molecular, and Microstructural properties of different starch gels

This study investigated the effects and underlying mechanisms of carbon dots (CDs) on the freeze-thaw stability of wheat starch (WS), corn starch (CS), and sweet potato starch (SPS) gels. The core innovation lies in revealing the differential antifreeze behavior of CDs in starch gels with different amylose-amylopectin ratios. After five freeze-thaw cycles, the incorporation of CDs significantly reduced the syneresis of WS-CDs and CS-CDs gels by 14.63% and 21.05%, respectively, while increasing that of SPS-CDs gels by 13.14%. CDs enhanced water-holding capacity and modified the microstructure of WS and CS gels, while exerting negligible or even opposite effects on SPS gels. Spectral analysis confirmed that CDs reduced the recrystallization of WS and CS gels but accelerated it in SPS gels during the freeze-thaw process. These findings indicate that the antifreeze effect of CDs depends on the structure of starch, mainly enhancing the freeze-thaw stability of WS and CS gels through the inhibition of ice crystal formation, competitive hydration and steric hindrance. This research establishes a theoretical foundation for the development of high-performance frozen starch-derived materials.