Advances in 3D printing of food and nutritional products.

The main advantage of both 3D printing (3DP) and 3D food printing (3DFP) over other technologies is the enormous capacity of both techniques for customization. Its use makes it possible to obtain products without planning and implementing a complex and costly manufacturing process. This makes 3DFP a technology of choice for the preparation of food products that meet specific needs, such as controlled nutritional or rheological properties. However, further technological developments are still needed before 3DFP can be considered fully useful for innovative and demanding applications. If both preparation and post-processing of materials based on 3D printing are optimized, aiming to reduce production time and/or complication for non-expert users, this would open a whole new range of possibilities. It is in this sense that the development of advanced 3DFP systems becomes a must. This chapter reviews current advances in extrusion-based 3D food printing systems, with in situ gelation and mixing as key aspects to better exploit the potential of 3DFP. On one hand, 3DFP systems based on in situ gelation (G3DFP) provide greater control over the final properties of the printed products, as the selection of adequate printing parameters gives the possibility of influencing the gelation process. On the other hand, mixing is indispensable for true 3DFP automation, so that the formulations do not have to be prepared by the user. Different innovative 3DFP systems based on gelling and/or mixing are presented in this chapter. Finally, the status and future of extrusion-based 3DFP, and its application in the production of customized foods for specific needs, are also overviewed.