Exploring the mechanism of variation in 3D printing accuracy of cassava starch gels during freezing process

Abstract

This study investigated the mechanism of changes in the 3D printing performance of cassava starch (CS) gels during freezing process from the perspective of multi-scale structure and gel properties. When the freezing time was before the subcooling period, the variation of 3D printing accuracy was mainly affected by starch retrogradation. During this period, the increase in the proportion of short-medium amylose(X∼100–5000) lead to an increase in the short-range ordered structure and crystallinity of CS, which in turn enhanced the storage modulus and structural recovery. In this circumstance the rigidity and support of the gel system increased, thus improving the printing performance of the 3D printed products. Conversely, the initiation of ice crystal expansion during and beyond the freezing time in the subcooling period damaged the short-range ordered structure of starch, leading to the increment of pore size and structural laxity in the sub-microstructure. Moreover, the free water content (A23) increased and the storage modulus decreased. These changes caused a reduction in the water-holding capacity and structural stability of CS gel, and thus decreased the printing accuracy of the final products. This study provides insight into 3D printing applied in the freezing process of starchy foods.