Effect of Ca2+ on 3D printing accuracy and antioxidant efficacy of nano starch-lutein surimi: mechanical properties, chemical bonds and release rate

BACKGROUND Nano starch-lutein (NS-L) can be used in three-dimensional (3D) printed functional surimi. However, the lutein release and printing effect are not ideal. The purpose of this study was to facilitate the function and printing properties of surimi by adding the combination of calcium ion (Ca 2+ ) and NS-L. RESULTS Printing properties, lutein release and antioxidation of printed Ca 2+ -NS-L-surimi were determined. The NS-L-surimi with 20 mM kg −1 Ca 2+ had the best printing effects (fine accuracy, 99 ± 1%). Compared to NS-L-surimi, the structure became denser after adding Ca 2+ , the gel strength, hardness, elasticity, yield stress ( τ ), water holding capacity of Ca 2+ -NS-L-surimi increased by about 17 ± 4%, 3 ± 1%, 9 ± 2%, 20 ± 4%, 40 ± 5% respectively. These enhanced mechanical strength and self-supporting ability to resist binding deformation and improve printing accuracy. Moreover, salt dissolution and increased hydrophobic force by Ca 2+ stimulated protein stretching and aggregation, leading to enhancement of gel formation. Decreased printing effects of NS-L-surimi with excessive Ca 2+ (> 20 mM kg −1 ) caused by excessive gel strength and τ , leading to strong extrusion force and low extrudability. Additionally, Ca 2+ -NS-L-surimi had higher digestibility and lutein release rate (increased from 55 ± 2% to 73 ± 3%), because Ca 2+ made NS-L-surimi structure porous, which promoted contact of enzyme-protein. Furthermore, weakened ionic bonds reduced electron binding bondage that combined with released lutein to provide more electrons for enhancing antioxidation. CONCLUSION Collectively, 20 mM kg −1 Ca 2+ could better promote printing process and function exertion of NS-L-surimi, facilitating the application of 3D printed functional surimi. © 2023 Society of Chemical Industry.