Printability prediction of three gels for 3D food printing

3D food printing is an innovative technique in recent years. This technique has great potential for food customization. It offers great variety of shapes, dimensions, flavours, textures, etc. It has been applied to elaborate different foods such as cookies, mashed potatoes, gels, etc. To obtain new formulations suitable for printing, it is important to carry out printability studies. These studies seek to know the printability and shape stability of formulations and is related to rheological and textural properties. Some authors are correlating printability with rheological and physico-chemical parameters. The objective of this study was to characterize the textural and rheological properties of three gels of different formulation for predict their printability. The gels are composed of 5% porcine gelatin plus 2% carrageenan-i (Gp+I), 4% bovine gelatin with 0.5% carrageenan-k (Gb+K) and 4% methylcellulose (MC). An extrusion test to determine the force required for printing and an oscillatory rheological test to determine their viscoelastic properties were carried out. The results showed that for printing Gp+I and Gb+K a lower maximum force is needed than for MC, being 45, 60 and 83 N, respectively. The average force required to extrude MC varies less than the other samples. The three samples showed a predominantly elastic behaviour. Modules between 100 Pa and 10,000 Pa indicate a zone of good impression, all modules were in that zone except for MC whose viscous modulus was 84 Pa. In terms of stability, the damping factor gave values between 0.14 (Gb+K) and 0.37 (MC), being indicative of weak gels. Observing the ratio rgH/G' for the above damping factors, it was estimated that the maximum height of the samples should be 0.8 cm, 1 cm and 0.008 cm for Gp+I, Gb+K and MC, respectively, to exhibit 5% deformation after 1 hour for a 3 cm diameter cylinder.