Optimizing Printability of Rice Protein-Based Formulations Using Extrusion-Based 3D Food Printing

Abstract

The purpose of this study was to investigate the application of an innovative extrusion-based 3D food printing (3DFOODP) technique in developing rice protein-starch (RP-S) gel-based products. The effects of 3DFOODP conditions were examined, which included variations in the concentrations of rice protein (RP) and corn starch (S) (15, 17.5, and 20 wt.%), nozzle size (0.8, 1.5, and 2.5 mm), printing temperature (40°C, 60°C, and 80°C), and ingredient flow speed (5.7, 6.3, and 6.9 mL/min). A hollow cylindrical model was chosen as a test object to determine the printability of RP-S gels. The best 3D printability was achieved using an RP concentration of 17.5% and an S concentration of 15% at 60°C printing temperature with a nozzle size of 1.5 mm, and ingredient flow speed of 6.3 mL/min. With increasing the RP concentration, a rise in apparent viscosity, loss, and storage moduli was observed. The recovery test showed the gels' rapid and reversible response. The freeze-dried 3D-printed RP-S gels showed a porous granular structure, depending on the printing temperature. No chemical interactions between the RP and S were observed as analyzed by FTIR. Overall, RP, in combination with S, provides a new opportunity for the 3DFOODP and their utilization by the alternative protein industry.

Keywords: 3D food printing; morphology; protein; rheology; rice; starch.

FIGURE 1

3D‐printed cylinder consisting of RP and S and hollow cylindric model with height (h) = 3.5 cm, internal radius (r) = 1.5 cm, external radius (R) = 2.0 cm, and thickness (b) = 0.5 cm.

FIGURE 2

Pictures of (a) RP‐S gels 3D printed with various concentrations (printing temperature: 60°C, nozzle size: 1.5 mm, and flow speed: 6.3 mL/min), (b) RP‐S gels 3D printed with constant S concentration of 15 wt.% at various RP concentrations and printing temperatures (nozzle size: 1.5 mm, and flow speed: 6.3 mL/min), (c) RP‐S gels 3D printed with constant S concentration of 15 wt.% at various RP concentrations and nozzle sizes (printing temperature: 60°C, and flow speed: 6.3 mL/min), and (d) RP‐S gels 3D printed with constant S concentration of 15 wt.% at various RP concentrations and ingredient flow speeds (printing temperature: 60°C, and nozzle size: 1.5 mm). RP, Rice protein; S, starch.

FIGURE 3

(a) Apparent viscosity as a function of shear rate, (b) storage (G′), and loss (G″) moduli as a function of angular frequency, (c) strain sweep curves, (d) temperature ramp cues, (e) loss tangent as a function of temperature, and (f) recovery tests of RP‐S gels at a S concentration of 15 wt.% and RP concentrations of 15, 17.5, and 20 wt.%.

FIGURE 4

SEM images of freeze‐dried 3D‐printed rice protein‐starch (RP‐S) gels consisting of 15 wt.% S and 17.5 wt.% RP concentration using a nozzle size of 1.5 mm at various printing temperatures.

FIGURE 5

XRD patterns of (S) starch, (RP) rice protein, and freeze‐dried 3D‐printed RP17.5:S15 gels produced using printing temperatures of (40°C) 40°C, (60°C) 60°C, and (80°C) 80°C. CI, Crystallinity index.

FIGURE 6

ATR‐FTIR spectra of (S) starch, (RP) rice protein, and freeze‐dried 3D‐printed RP17.5:S15 gels produced using printing temperatures of (40°C) 40°C, (60°C) 60°C, and (80°C) 80°C.