Gel & three-dimensional printing properties of sheep plasma protein-surimi induced by transglutaminase

The objective of the present work was to investigate the effects of transglutaminase (TGase) on rheological property, three-dimensional (3D) printing property, textural property, water holding capacity, water distribution and secondary structures of sheep plasma protein-surimi gels. The results from 3D printing experiments showed that compared with a control group, sheep plasma protein-surimi gels added with 0.2% and 0.3% TGase presented good printing properties. During the heating process, high G′ values were achieved in the formation of sheep plasma protein-surimi gels due to the enhancement of connections between proteins by TGase. Compared with the control group, the hardness, springiness, and chewiness of the 3D printed sheep plasma protein -surimi gels reached the maximum with the addition of 0.4% TGase, which increased by 15.28%, 14.09%, 32.46% respectively. Furthermore, the concentration of the added TGase was directly proportional to the breaking force of the surimi gels. Adding 0.4% TGase increased the gel strength to a maximum value of 185.04 N × mm. The water-holding capacity of the 3D printed surimi gel was also significantly increased after the addition of TGase, as evidenced by low-field nuclear magnetic resonance. The addition of TGase restrained more residual water and increased the T21 relaxation time. The Raman spectroscopy analysis showed that the α-helix percentage increased significantly with the addition of TGase. Taken together, the results suggest that the 3D printability and gel properties of sheep plasma protein-surimi gel can be effectively improved by TGase.