Improvement in quality of frozen sweet potato starch vermicelli during freeze-thaw cycles by curdlan addition and its mechanism

This study investigated the effect of different curdlan (CUD) concentrations on the frozen sweet potato starch vermicelli (FSPSV) during 10 freeze-thaw (FT) cycles. The results showed that CUD efficiently mitigated the quality deterioration of FSPSV at all levels during FT cycles, with a more pronounced effect observed at higher concentrations. Notably, the 1.20% CUD sample at FT-10 still exhibited superior textural properties compared to the control at FT-0. The SEM and FTIR results illustrated that CUD displayed intense interactions with SPS to form a denser gel network structure and thus improved the freeze-thaw stability of FSPSV by decreasing the freezable water content, total relaxation time, and porosity of FSPSV by 16%, 47%, and 66%, respectively. In addition, analysis of the CUD-SPS-water ternary system further revealed the contribution of CUD in establishing a more robust gel system to ameliorate the adverse effects of ice crystals, with the notable improvement in the average particle size and peak viscosity of SPS, reducing the Tan σ value and phase transition time of SPS gel from 0.58 and 181.67 min to 0.29 and 142.67 min, respectively. Our results suggested that CUD may provide new insights into its application in frozen starch-based food. •CUD can mitigate quality deterioration of FSPSV during FT cycles.•FSPSV fortified with CUD showed good quality during FT cycles.•CUD interacted with SPS and water during heating to construct a robust gel system.