4D printing: Recent advances and proposals in the food sector

4D printing technology has attracted extensive attention in academic and industrial circles since 2013 although commercialization still requires additional research and development. 4D food printing is an extension of 3D printing, which permits customization of new food products. Compared with aerospace, automobile, robotics, biomedicine and materials etc, there are few reviews on 4D food printing. This review shows recent advances in 4D printing technology applied to foods. To adapt current 4D printing technology to foods it is necessary to improve the extrusion printer and develop the necessary software. Aspects of recombination of different food materials and reasons of alterations in color, shape, flavor and nutrition via 4D food printing are discussed critically. The key to the success of 4D food printing and diverse solutions to the corresponding problems are outlined and analyzed. Future prospects for 4D food printing technology are discussed along with research and development needs. At present, 4D food printing experiment is mainly based on soy protein isolate, starch and hydrogels and is realized through material properties, internal structural design and spatial arrangement of recombined food materials. The stimulation factors responsible for causing alteration of 3D printed products include pH, water absorption, microwave and temperature, resulting in deformation, modification of color, flavor and nutritional value. It is noteworthy that 4D food printing is still at research stage. There are opportunities for enhancement in the link between internal structure and stimulation, design of the printer, printing software, printing materials as well as evaluation of the properties of the printed foods. • The knowledges of 4D food printing are described. • The applications of 4D food printing are reviewed. • The problems and possible solutions of 4D food printing are reviewed. • Expectations and suggestions of 4D food printing are outlined.