Effects of gel spatial structure and water state on 3D printability: A case study of honey bee pupa protein and soybean dietary fiber

The performance of 3D food printing for hydrogels largely depends on the gel spatial structure and water state. However, the mechanism of microstructure and water state that affects the 3D printing performance of hydrogels remains unclear. Our previous studies found that the hydrogel made from honey bee pupae, a rich source of high-quality protein, has good fluidity but poor structural stability, limiting its use in 3D printing. Based on it, honey bee pupa protein (HBPP) added with soybean dietary fiber (SDF) was selected as a case study in this work. The results revealed that HBPP gel had good fluidity but weak mechanical strength, which was guided by the firm immobilization of water molecules and the lack of a rigid three-dimensional network structure. However, upon adding SDF, the rigid network structure of HBPP gel was enhanced and the degree of water immobilization was reduced. HBPP-SDF gel had better structural stability than HBPP gel and lower water migration ability than SDF gel. Additionally, SDF and HBPP complemented each other, thereby improving the 3D printing performance of the gel. Based on the findings, a possible microstructure evolution mechanism of different types of gels during 3D printing was proposed. Out of all the HBPP-SDF gels evaluated, the HBPP-SDF gel with an optimum SDF concentration of 30% demonstrated the best printing performance.