Abstract: In order to clarify the effect of vitamin C (VC) on physicochemical properties and digestibility of lotus seed starch (LSS) during freeze-thaw cycles, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to characterize the multi-scale structure of the starch, and its rheological properties and in vitro digestibility were determined. The results showed that the pore size of starch gels became lager and the syneresis decreased with increasing freeze-thaw cycles. VC addition promoted the formation of tighter gels during freeze-thaw cycles, resulting in lower syneresis and improved freeze-thaw stability. Overall, the degree of starch recrystallization increased with increasing freeze-thaw cycles. The addition of VC decreased the digestibility of frozen-thawed LSS. One potential reason may be that the addition of VC enhanced short-range ordered structure, double helix structure and relative crystallinity of LSS. In conclusion, VC can improve freeze-thaw stability of LSS and reduce the digestibility of frozen-thawed LSS.

Key words: lotus seed starch; vitamin C; freeze-thaw processing; digestibility