Improvement of rheological, network structure and 3D printing properties of heat-induced egg yolk low density lipoprotein hydrogel: The role of bivalent metal ions.

The spherical particles structure of egg yolk low-density lipoprotein limits the gelation of egg yolk. This study aimed to improve the gel properties of heat-induced duck egg low-density lipoprotein (LDL) gels by using bivalent metal ions (Ca, Mg and Zn). Results showed that the hardness, energy storage modulus, loss modulus and strain value of LDL gel increase gradually with increasing of bivalent metal ion concentration. Furthermore, the order of secondary structure (the number of β-sheets and β-turns) and aggregation behavior of LDL gels were progressively enhanced with increasing ion concentration. These changes are due to more proteins, lipids and water are exposed after the addition of ions, and the hydrophobic interactions are stronger, resulting in the formation of a dense gel network structure. Besides, the 3D printed models with LDL gel showed good support and smoothness. These results will promote the improvement of processing technology of gel-like egg products.