Prepared by: Dr Nurul Izzah Khalid

Senior Lecturer,

Faculty of Food Science and Technology,

Universiti Putra Malaysia

Three-dimensional (3D) food printing is an additive manufacturing method that forms food layer by layer based on a digital design. In food science and technology, a basic understanding of this printing mechanism helps evaluate why some printed products remain neat after printing, while others slump, collapse, or produce uneven layers.

3D food printing workflow (brief)

 Digital design (CAD): The food shape is designed using software.

• Slicing: The model is divided into thin layers.
• Machine instructions: The nozzle movement path and material output rate are generated.
• Printing process: The material is deposited layer by layer along the defined path.
• Important note: The machine follows instructions, but material properties determine whether the structure remains stable or deforms after printing.

Extrusion-based printing mechanism

The most common mechanism in 3D food printing is extrusion, where food material is forced out through a nozzle to form a pattern on the print platform. As the material moves inside the nozzle, it experiences high shear stress, which makes it flow more easily. After exiting the nozzle, shear decreases, and the material must quickly hold its shape so that the newly deposited layer does not spread or sink. At the same time, the new layer must adhere to the previous layer to build a strong structure. If the material is too fluid, it flows easily and causes slumping; if it is too thick or not homogeneous, the flow may be disrupted and can clog the nozzle.

Why “food ink” must balance flow and stability?

A printable material must have two properties that seem contradictory but must be balanced: it should flow easily during printing and be stable after printing. In practice, a “good” material extrudes smoothly when forced through the nozzle, but does not continue spreading after being deposited. This concept can be understood as a transition from a “formable” state during the process to a “shape-retaining” state after the process.

Material properties that most affect print outcomes

Several material properties are closely linked to printing performance. Viscosity determines whether a material is too fluid (slumps easily) or too thick (difficult to extrude). Yield stress helps the material retain its shape because it does not flow easily when no force is applied. Structural recovery after shear (thixotropy) is important because the material must flow more easily during printing, then quickly become stable again after shear decreases. In short, materials that remain stable after printing usually show good structural recovery within a short time.

Process parameters that often cause structure “failure”

In addition to material properties, process settings determine product quality. Nozzle diameter affects the thickness of printed strands: smaller nozzles produce finer details but clog more easily, while larger nozzles provide more stable flow but lower resolution. Layer height affects bonding between layers: layers that are too high may not fuse well, and the structure can collapse. Flow rate must match the nozzle travel speed: if the flow rate is too high, material accumulates, and the surface becomes uneven; if too low, layers become discontinuous, and the structure becomes weak.

A simple way to analyse problems using the “Material–Process–Structure” framework

For systematic diagnosis, the Material–Process–Structure framework can be used. Under material, viscosity, yield stress, thixotropy, and homogeneity are assessed. Under process, nozzle diameter, layer height, flow rate, and nozzle speed are checked. Under structure, dimensional accuracy, shape stability, and defects such as slumping, collapse, or wavy surfaces are observed. This framework helps connect visible symptoms to reasonable causes and propose evidence-based adjustments.

Conclusion

3D food printing is an engineering process that requires good matching between material properties and process parameters. Its main mechanism is the ability of the material to flow in a controlled manner during extrusion and become stable again after deposition, while ensuring sufficient interlayer adhesion to support the structure. By understanding these basic concepts, the causes of printing failures can be evaluated more systematically, and suitable improvements can be proposed.

Date of Input: 13/03/2026 | Updated: 13/03/2026 | nurulizzah