Development of a Desktop Food Printer for Dough Extrusion Jie Sun Xi'an Jiaotong-Liverpool University, Suzhou 215123, People’s Republic of China Email: Jie.Sun@xjtlu.edu.cn Geok Soon Hong, Sanjairaj Vijayavenkataraman, and Johandy Tantra Department of Mechanical Engineering, National University of Singapore, Singapore 117542, Singapore Email: {mpehgs@nus.edu.sg, vijayavenkataraman@u.nus.edu} Abstract—Food printing is increasingly being explored for mass customization of food. This study reports the development of a desktop 3D printer for printing cookie dough. Specifically, the effect of different extruder profiles on the properties of the extruded dough, are experimentally evaluated to obtain an optimal design which consists of a screw, connection profile between the cartridge and the syringe, and nozzles. Three different nozzle designs, namely, conic, fat, and skinny nozzle profiles are tested. The conic nozzle design gives a good balance between the speed of extrusion and extrusion consistency, compared with the other designs. It is further modified to add a straight tube- like section to improve the extrusion consistency. This study demonstrates the importance of dough extruder design in food printing. Index Terms—food printer design, food printing, dough printing I. INTRODUCTION Digitalizing food printing has a great potential of producing customized food with complex geometries, tailored texture, and nutritional content. As the population gets older, an estimated 15 - 25% of this population experiences swallowing difficulty [1] and they obtain nutrition from pureed food, most of which is unappealing and unappetizing. This may result in further deterioration of health. Food printing is a conceivable way of providing soft, nutritious and innovative textured food for the elderly. This enables the mass customization of food to meet individual customer needs and shortens the supply chain from producers to end consumers, ensuring freshness. A range of 3D printing methods has been utilized for food printing, such as selective laser sintering/hot air sintering, hot-melt extrusion/room temperature extrusion, binder jetting, and inkjet printing [2]. Among them, the extrusion-based 3D food printing is the most widely adopted method. The ideal target of the extrusion-based 3D food printing is to achieve the output of the conventional food extrusion processing physically with a digitalized design and a personalized nutrition control. Manuscript received May 11, 2018; revised August 11, 2018. The extrusion process in food printing is a digitally- controlled, robotic construction process which can build up complex 3D food products layer by layer [3]. It starts with the loading of material, pushing the material out of the nozzle in a controlled manner, moving the material stream according to a predefined path, and eventually bonding the deposited layer to form a coherent solid structure. Researchers have studied rheological properties of extruded food materials and explore their influences on flow conditions, viscosity, and self-supporting structures. Liu et al. [4] examined the rheological properties of a mixture of mashed potatoes and potato starch to evaluate its characteristics during printing. Wang et al. [5] revealed that the rheological behavior of fish surimi gel with sodium chloride (NaCl) in food printing. The relationship between extrusion process parameters and extruded food pieces has also been discussed. For example, the layer thickness is determined by the stage speed, extrusion rate and diameter of the nozzle. However, the relationship between the extruder design and extrusion process has not been discussed much. In this study, a desktop Food Printer is designed to print cookie dough, since cookies are regarded as the most available snack for everyone. The printer aims to smoothly extrude natively printable materials like dough, cheese, frosting, creamy peanut butter, jelly, and Nutella at room temperature, and fabricate complex confections with high repeatability, which are difficult to make by hand. The extruder design is discussed which consists of a cartridge, screw, nozzle, and the connection profile between syringe and cartridge, with the target to optimize food printing process. II. EXTRUSION BASED FOOD PRINTER A. Introduction to Extrusion-Based Food Printing The current extrusion-based food printing starts with designing a virtual 3D model. Slicing software translates this model into individual layer patterns and finally generates machine codes for printing. After uploading the codes to a printer and choosing a preferred food recipe, the food printing starts. According to the layer patterns International Journal of Food Engineering Vol. 4, No. 4, December 2018 ©2018 International Journal of Food Engineering 316 doi: 10.18178/ijfe.4.4.316-321