3D food printing—An innovative way of mass customization in food fabrication. © 2015 Jie Sun, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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REVIEW ARTICLE

3D food printing—An innovative way of mass customization in food fabrication Jie Sun1,2*, Zhuo Peng3,4, Liangkun Yan3, Jerry Y. H. Fuh4 and Geok Soon Hong4 1 Industrial Design Department, Xi’an Jiaotong-Liverpool University, Suzhou 215123, China 2 National University of Singapore (Suzhou) Research Institute, Suzhou Industrial Park, Suzhou 215123, China 3 Keio-NUS CUTE Center, National University of Singapore, Singapore 4 Department of Mechanical Engineering, National University of Singapore, Singapore

Abstract: About 15%–25% of the aging population suffers from swallowing difficulties, and this creates an in-creasing market need for mass customization of food. The food industry is investigating mass customization tech-niques to meet the individual needs of taste, nutrition, and mouthfeel. Three dimensional (3D) food printing is a potential solution to overcome drawbacks of current food customization techniques, such as lower production ef-ficiency and high manufacturing cost. This study introduces the first-generation food printer concept designs and functional prototypes targeted to revolutionize customized food fabrication by 3D printing (3DP). Unlike the ro-botics-based food manufacturing technologies designed to automate manual processes for mass production, 3D food printing integrates 3DP and digital gastronomy technique to customize food products. This introduces artistic capabilities into domestic cooking and extends customization capabilities to the industrial culinary sector. Its ap-plication in domestic cooking or catering services can not only provide an engineering solution for customized food design and personalized nutrition control, but also has the potential to reconfigure customized food supply chains.

In this paper, the selected prototypes are reviewed based on fabrication platforms and printing materials. A de-tailed discussion on specific 3DP technologies and the associated dispensing/printing process for 3D customized food fabrication with single and multi-material applications is reported. Lastly, impacts of food printing on custo-mized food fabrication, personalized nutrition, food supply chain, and food processing technologies are discussed. Keywords: customized food fabrication, mass customization, 3D printing, platform design, multi-material

*Correspondence to: Jie Sun, Industrial Design Department, Xi’an Jiaotong-Liverpool University, China; Email: jie.sun@xjtlu.edu.cn

Received: May 30, 2015; Accepted: June 21, 2015; Published Online: July 2, 2015 Citation: Sun J, Peng Z, Yan L K, et al. 2015, 3D food printing—An innovative way of mass customization in food fabrication. In-ternational Journal of Bioprinting, vol.1(1): 27–38. http://dx.doi.org/10.18063/IJB.2015.01.006.

1. Introduction

bout 15 to 25 percent of people over the age of 50 years old suffer from difficulties in swallowing. Pureed foods can provide the

necessary nutrition to them, but most of these foods are unappealing and unappetizing[1]. The Netherlands Organisation for Applied Scientific Research (TNO) has proposed printing of pureed food to help the el-

derly cope with their chewing and swallowing prob-lems[2]. TNO has also suggested printing customized meals for seniors, athletes, and expectant mothers by varying nutrient components’ levels, like proteins and fats. An increasing market need for mass customiza-tion on shapes, colors, flavors, textures, and nutrition covers most of the food products, including persona-lized hamburgers, coffees, ice creams, cakes, and bis-cuits.

A

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Many food forming or food structuring techniques are optimized for mass production. Customized foods are currently designed and made by specially-trained artisans using techniques, which may involve assem-bling the various prefabricated components to meet customers’ preferences. In general, the cost for pro-ducing a limited number of customized pieces is sig-nificantly high. To achieve mass customization in an economic way, we need an innovative method to de-sign and fabricate customized foods. With the rapid development of online shopping and information technologies, food customization techniques are expe-riencing a great revolution. Sloan[3] has listed three ways to customize food design: (i) create online virtual customized food by interactive interfaces and invite customers to share their design and personal experiences, such as donut design with varied shapes, dough, filling, frosting, and topping, (ii) configure online visual products for self-service and online order, such as building your own pizza by Domino’s pizza’s visual product configurator, and (iii) provide food co-creation sites for gift giving with highly unique food products, such as choosing a chocolate base and adding exotic toppings to customize chocolate bars.

Three-dimensional (3D) food printing, also known as Food Layered Manufacture (FLM) [4], can be one of the potential alternatives to fabricate customized food products. It integrates additive manufacturing and dig-ital gastronomy techniques to produce 3D cus-tom-designed food objects without object-specific tooling, molding or human intervention. Thus, this technique can increase production efficiency and re-duce manufacturing costs for mass customization in food fabrication.

1.1 Food Printing and Robotics-based Food Man-ufacturing

Cooking is one of the most important activities in our life. A robotic chef capable of following recipes would have many applications in both household and indus-trial environments. For example, cookie-baking robots can locate ingredients, mix them in the correct order, and place the resultant dough in a baking tray[5]. These robots, equipped with operation/recipe libraries, can perform basic tasks such as picking up an object, putting it down or pouring[6]. Such robotics-based techniques are generally designed to replace manual processes in mass customization of food so as to re-duce workload, save labor cost, and improve the effi-ciency of food manufacturing. Food manufacturers are satisfied with such progress, and they are not aware of

the unique features of food printing[7]. 3D printing (3DP) is a digitally-controlled robotic

construction process, which can build up complex solid forms layer by layer and apply phase transitions or chemical reactions to bind the layers together. Food printing integrates 3DP and digital gastronomy tech-niques to manufacture food pieces with mass custo-mization in shape, color, flavor, texture, and even nu-tritional value. As a result, a digital 3D model of cus-tomized food designs can be directly transformed to a finished product in a layered structure[8]. Digital gastronomy brings in cooking knowledge into food fabrication so that our eating experiences can go beyond merely taste and cover all the aspects of ga-stronomy[9]. 3D printing is not only a novel approach to food fabrication, but also an economical and po-werful technique for mass customization.

1.2 Overview

A number of articles and papers pertaining to food printing have been published over the past few years. Most of them have focused on fabricated, novel food items. Recently, some researchers have started inves-tigating fundamental-level issues, such as converting alternative ingredients into tasty products for health and environmental reasons. However, such informa-tion is scattered in various publications with different technical focuses. The objective of this paper is to gather, analyze, categorize and summarize the availa-ble information pertaining to the technology and its impact on food processing. The rest of the paper is organized as follows: Section 2 discusses food printer concepts and platform designs, as well as diverse printing materials. Section 3 investigates the 3DP technologies for food printing from an engineering perspective, including dispensing and printing tech-nologies, multi-material and multi-printhead, and mixing techniques. Section 4 discusses the impact of food printing on customized food designs, persona-lized nutrition, food supply chain, and food processing technologies. Finally, a conclusion is presented in Section 5.

2. Food Printer Concepts and Platform Designs

“Food synthesizer,” a very primary food printer concept, is described in the movie Star Trek: The Original Series in the 1960s, a “replicating machine” that could synthesize meals based on user requirements. The concept reveals people’s desire of

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instantly making personalized meals and replicating exciting food designs. The first generation of food printer concept designs and prototypes, designed 10 years ago, are now emerging into the public domain. With a short history, a few research projects were conducted from concept designs to an in-depth re-search on material extrusion and deposition.

2.1 Conceptual Ideas

Nanotek Instruments Inc. patented a rapid prototyping and fabrication method for 3D food objects in 2001, such as a custom-designed birthday cake[10]. However, no physical prototype was built. Nico Kläber[11] pro-posed a Moléculaire concept design in Electrolux De-sign Lab competition, which incorporated molecular gastronomy into the food printer design. This concept aimed to print multiple materials using a small robotic

arm and created a fully-customized meal using normal food. Philips Food Creation Printer introduced food cartridges to create custom-designed food products[12]. An interactive graphical user interface was proposed to select ingredients, quantities, shapes, textures, and other food properties. This idea is applicable to cus-tomize any 3D food product. However, all of these concept designs seem vastly unrealistic with no poten-tial of implementation.

Massachusetts Institute of Technology (MIT) in-troduced a digital gastronomy concept into food prin-ter design and presented three conceptual designs as shown in Table 1[13]

. Each conceptual design focused on different aspects of gastronomy right from mixing, modelling, to transformation. These concepts seem more realistic compared to the previous conceptual designs, but are still far away to be technically feasible.

Table 1. Summary of conceptual designs on food printer

2.2 Platform for Food Printing

The recent expansion of low-cost desktop 3D printers has led to food printing development since they utilize very similar printing platforms. Food printer platform consists of an XYZ three-axis stage (Cartesian coordi-nate system), dispensing/sintering units, and user in-terface. With computer-controlled, three-axis moto-rized stage and material feeding system, these plat-forms can manipulate food fabrication process real-time. A food design model, after being translated into machine path planning language (G-code, M-code, etc.), can be easily defined in terms of printing speed, deposition speed, and other geometric parameters. Food composition can be deposited/sintered essen-tially point-by-point and layer-by-layer according to computer design model and path planning. At least four functions are proposed in order to invent and personalize new recipes rather than simply automate traditional food fabrication process. The proposed

functions are: metering, mixing, dispensing, and cooking (heating or cooling)[13]. Only the dispensing and cooking functions are available in the current commercial or self-developed food printing platforms. (1) Food printers based on commercial platforms: To simplify development process and shorten develop-ment time, researchers modified commercially availa-ble, open source 3DP platforms for the purpose of food printing. Common modifications are to replace the original printhead with a specially-designed dis-pensing unit having an additional valve to control ma-terial feed rate, or replacing the standard inkjet binder with food grade materials like starch mixtures.

The Fab@Home system, although not specifically designed for food applications, was one of the univer-sal desktop fabricators compatible with food mate-rials[14]. Millen from Massey University[15] integrated Frostruder MK2 on MakerBot platform to extrude frost, where two solenoid valves were used to control the flow rate of creamy peanut butter, jelly, and Nu-

Concept Focus Design Platform Difficulties Virtuoso Mixer

To combine and mix diverse ingredients, to control their quantities, types, and source

Top layer: storage containers to monitor temperature, humidity, and weight

2nd layer: processing chambers dedicated to mixing, whisking, and crushing

Bottom layer: extrusion unit with thermal control

Distribution and metering between the layers

Machine cleaning Waste minimization

Digital Fabricator

Model and cook a combination of ingredients into specific shapes and dimensions

A set of refrigerated canisters A three-axis mixing/printing head onto the

printing surface A fabricator chamber

Refilling canisters Machine cleaning Material supply to mixing

head and storage system Robotic Chef Transform existing ingredients

into new flavors and design patterns

Two robotic arms with five-degree freedom A tool head to localize transformations such as

drilling, cutting, and dispensing A heating bed for cutting/cooking/sintering

Fabricate diverse food shapes

Complicated manipulation

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tella. Figure 1 shows a food printing platform with a printhead developed at the National University of Singapore. The platform is built based on a modified Prusa i3 platform with a self-developed extrusion printhead. A cookie dough consisting of flour, sugar, egg and butter, and food additives is used for this printing experiment.

(A) (B)

Figure 1. (A) Food printing platform and (B) Printhead

With the modified commercial platform, research-ers can quickly create complex food shapes, and compare the properties and fabrication processes of various food materials. However, these platforms are not flexible for further improvement and are only ap-plicable for a limited range of materials, and therefore they cannot support in-depth research. (2) Food printers based on self-developed platform: Self-developed platforms are built based on specific requirements, such as creating 3D sugar structures with a computer-controlled laser machine[16], building cheese and chocolate 3D objects from edible ingredients[17], or reducing the costs associated with freeform fabrication of sugar products using open-source hardware[18]. Self-developed platforms have a wide range of material choices, and printheads can be appropriately designed and implemented among a few candidates, and dispensing parameters. Therefore, fabrication process can be more flexible and optimized.

In both commercial and self-developed platforms, mechanical movements of substrate and dispensing head(s) are achieved through computer control. First, a digital 3D model is converted into multiple layer data (STL files), and then this data is interpreted into driving signals to stage driver motors through the re-gulated controller. The printhead moves and dispenses one layer at a time according to its own characteristic shape and dimensions, followed by binding and con-

solidation of these layers until the completion of a 3D object. (3) User control interface design: User control means full control of shape, ingredients, and materials, which may significantly impact the creative design of food. Thus, the user control interface design involves three functions: (i) providing tools for shape, design, and material selection for customized designing of food pieces; (ii) transforming this design into a digital 3D model; and (iii) planning dispensing pathway and processing–related parameters. It is essential to link this user interface with an open-access, web-based template library[19]. With this link, customers can de-sign their own personalized food pieces, as well as obtain or share design files online through a technol-ogy service provider.

2.3 Available Printing Materials

Raw materials and unprocessed ingredients usually have longer shelf life than the final food products. If food products can be quickly printed on the spot based on users’ requirements, people can have fresh meals all the time. Substantial efforts have been made to pre-process materials suitable for 3D printing and in-crease their thermal stability during post-processing. NASA[20] has funded a project to determine the capa-bilities of 3D food printing technology to ensure nu-trient stability for a variety of foods from shelf stable ingredients, while minimizing waste. Generally, the available printing materials can be classified into three categories based on their printability. (1) Natively printable materials: Natively printable materials like hydrogel, cake frosting, cheese, hum-mus, and chocolate can be extruded smoothly from a syringe[21]. The mixture of sugars, starch, and mashed potato were tested as powder materials in Z Corpora-tion powder/binder 3D printer[22]. A number of sugar teeth were fabricated for demonstration. However, none of them is the main course of meals. Some tradi-tional foods were tested for printability study using Fabaroni[23]. Judging by the printing viscosity, product consistency, and solidifying properties, the most suc-cessful material was pasta dough. Food products made by natively printable materials can be fully custo-mized for taste, nutritional value, and texture. Some of the natively printable materials are stable enough to hold the shape after deposition and do not require fur-ther post processing. Thus, they can be reserved for medical and space applications. Other composite for-mulations such as batters and protein pastes may re-

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quire post-processing to improve taste and nutrition absorption. This will make it more difficult for food product structures to retain their shapes[19]. (2) Non-printable traditional food material: Food like rice, meat, fruit, and vegetables, largely consumed by people daily, are not printable by nature. To enable their capability of extrusion, adding hydrocolloids in these solid materials has been approved and utilized in culinary fields. Lipton et al.[19] used simple additives to modify traditional food recipes and created com-plex geometries and novel formulations. Although solid foods and semi-solid liquids have already been manipulated to become printable by gastronomic tricks, it is difficult to test and modify the whole list of traditional food materials. One solution is to use a small group of ingredients to create a platform with extensive degrees of freedom of texture and flavor. By fine-tuning hydrocolloids’ concentrations, a very wide range of textures (i.e., mouthfeels) can be achieved such as cooked spaghetti, cake icing, tomato, etc. The flavors can be altered by adjusting the amount of fla-vor additives being added. Cohen et al.[21] experi-mented food texture using two hydrocolloid systems, and explored structural requirements for post- processing materials such as protein pastes and cake mixtures. (3) Alternative ingredients: Introducing alternative ingredients in food products can be one of the solu-tions to deal with the global crisis of food shortage. In the “Insects Au Gratin” project, Susanna Soares et al.[24] mixed insect powders with extrudable icing and soft cheese to shape food structures and make tasty pieces with 3D printing. When compared with traditional meat products, the protein concentration in insect powder, an alternative source for protein intake, is slightly higher. Food printing can greatly contribute to make unpleasant aesthetics and cultural background of insects more appealing to consumers. (4) Post-processing: A majority of traditional edibles need post-processing, such as baking, steaming, or frying after shapes are constructed. This involves dif-ferent levels of heat penetration and results in a non-homogenous texture. Lipton et al. successfully used a modified recipe with cocoa material to print cookies with complex internal geometries, which could retain their shape after the baking process[19].

Basically, the food printing process does not require a high energy source to completely remove liquid contents from food composition. But the fabricated layer should be sufficiently rigid and strong to support

its own weight and the weight of subsequent layers, without a significant deformation or change in shape.

3. 3D Food Printing Technologies

3D food printing has significant advantages in high-value, low volume food fabrication, particularly for customized items in mass food service. Some printers used thermal energy from laser/hot air/heating element to sinter or melt powder, and others used inkjet-type printing heads to accurately spray binder or solvent. A summary of the applicable 3DP technol-ogies can be found below.

3.1 Current 3D Food Printing Technologies

(1) Selective Sintering technology: Sugars and sug-ar-rich powders can be selectively sintered to form complex shapes. After a layer of fresh powder is spread, a sintering source (hot air in Figure 2(A) or laser in Figure 2(B)) moves along x- and y-axes to fuse powder particles so that they can bind together and form a solid layer. This process is repeated by continuously covering the fused surface with a new layer of material until the 3D object is completed[25]. TNO’s Food Jetting Printer[2] applied laser to sinter sugars and Nesquik powders. The sintered material formed the part whilst the un-sintered powder re-mained in place to support the structure. The Candy-Fab[18] applied a selective low-velocity stream of hot air to sinter and melt a bed of sugar. The fabrication powder bed is heated to just below the material melt-ing point to minimize thermal distortion and facilitate fusion among layers. Selective sintering offers more freedom to build complex food items in a short time without post-processing. It is suitable for sugar and fat-based materials with relatively low melting points. However, the fabrication operation is complicated as many variables are involved. (2) Hot melt extrusion: Hot-melt extrusion, also called fused deposition modeling (FDM), was first described in Crump’s work[26]. In Figure 3, melted semi-solid thermoplastic material is extruded from a movable FDM head and deposited onto a substrate. The material is heated slightly above its melting point so that it solidifies almost immediately after extrusion and fuses to the previous layer.

This technology is widely applied to create persona-lized 3D chocolate products[10,17,27]. Using FDM-based extrusion system, Hao et al.[17] compared the material properties among various food items and printed 3D

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chocolate products with different shapes and sizes. MIT Researchers used hot melt chocolate as a dis-pensing liquid and developed a functional prototype named “digital chocolatier” to fabricate customized chocolate candy[13,28]. In this research, the compressed

air was applied to melt chocolate and force it out of the chambers. A “3D Food-Inks Printer” which dis-penses 3D color images on extruded base material may also fall into this category[29], while a post-processing step was applied to fuse the layers together.

Figure 2. (A) Selective hot air sintering and (B) Selective laser sintering

The advantages of food printer designed based on FDM include compact size and low cost of mainten-ance. However, shortcomings such as a seam line be-tween layers, long fabrication time, and delamination caused by temperature fluctuation, can be further im-proved.

Figure 3. Hot-melt extrusion (FDM)

(3) Powder bed binder jetting: In standard binder jet-ting technology, each powder layer is distributed evenly across the fabrication platform, and liquid binder sprays to bind two consecutive layers of powd-er[30]. As shown in Figure 4, the powder material is usually stabilized by spraying water mist to minimize the disturbance caused by binder dispensing. In edible 3D printing project, Southerland et al.[22] utilized su-gars and starch mixtures as a powder material and a Z Corporation powder/binder 3D printer as a fabrication

platform. Sugar Lab[31] used sugar and different flavor binders to fabricate complex sculptural cakes for wed-dings and other special events. This fabrication adopted 3D Systems’ Color Jet Printing technology, and the material and fabrication process met all the requirements of food safety. Binder Jetting offers ad-vantages such as faster fabrication, ability to build complex structures, and low ingredients cost. But the fabricated products suffer from rough surface finish and high sugar content, and the machine cost is high. Post-processing may be required, such as curing at higher temperature to strengthen the bonding among layers. (4) Inkjet printing: As shown in Figure 5, inkjet food printing dispenses multi-material streams/droplets from a syringe-type multi-channel printhead in a drop-on-demand way and creates 3D edible food products such as cookies, cakes, or pastries. It involves

Figure 4. Powder bed binder jetting

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pre-patterning food items at multiple layers of processing. The De Grood Innovations’FoodJet Prin-ter[32] used pneumatic membrane nozzle-jets to drop on-demand materials onto pizza bases, biscuits, and cupcakes. The ejected stream/droplets fall under grav-ity, impact on the substrate, and dry through solvent evaporation. The drops can form a two and half di-mensional digital image as a decoration or surface fill.

Figure 5. Inkjet Printing

Compared with other methods, 3DP is an economi-cal and innovative way for mass customization in food fabrication. The quality of fabricated food items de-pends on the process and planning rather than people’s skill. This technology can easily and accurately per-form fabrication based on customer demands. Table 2

is a summary of current commercial 3DP applications in food printing, in terms of materials, fabrication platforms, and products.

3.2 Multi-material and Multi-printhead

Applying multiple materials is quite common in Cus-tomized food, including traditional food materials, additives, and ingredients extracted from algae, beet, or even insects. However, most of the food printer-s[24,33]

Researchers tried multiple-printhead using Fab@Home 3D printer and tested with frosting, choc-olate, processed cheese, muffin mix, hydrocolloid mixtures, caramel, and cookie dough

use a single printhead to extrude a mixture of multiple materials. Thus, they are not capable of con-trolling material distribution or composition within a layer or a structure. To achieve controlled material deposition and distribution in a drop-on-demand way, more printheads are proposed. For multiple-printhead, the data of individual layer is sent to a platform con-troller (either in a commercial or a DIY platform), which activates a corresponding printhead and con-trols its feeding rate. Hence, food printers may per-form multi-material object fabrication with higher geometric complexity and self-supporting structure.

[19]. Dual-material printing was only achieved for a limited material set.

Table 2. Comparison of 3DP technologies in food printing

Hot-melt extrusion Sintering technology Inkjet powder printing Inkjet printing

Materials Food polymers such as chocolate

Low melting powder such as sugar, NesQuik, or fat

Powder such as sugars, starch, corn flour, flavours, and liquid binder

Low viscosity materials such as paste or puree

Viscosity 103 ~ 105 cP Not applicable 1 ~ 10 cP (Binder) 5×102 ~ 5×103 cP

Platform • Motorized stage • Heating unit • Extrusion device

• Motorized stage • Sintering source (laser or hot air) • Powder bed

• Motorized stage • Powder bed • Inkjet printhead for binder

printing

• Motorized stage • Inkjet printhead • Thermal control unit

Printing Resolution*

Nozzle diameter: 0.5 ~ 1.5 mm

powder size:100 μm nozzle diameter≤ 50 μm Powder particle ≤100 μm

nozzle diameter≤50 μm

Fabricated Products

Customized chocolates Food-grade art objects, toffee shapes

Sugar cube in full color Customized cookies, Bench-top food paste shap-ing

Pros • Cost effective • Fast fabrication

• Better printing quality • Complex design

• More material choices • Better printing quality • Full color potential • Complex design

• Better printing quality

Cons • Low printing quality • Expensive platform • High power consumption • Limited materials

• Slow fabrication • Expensive platform

• Slow fabrication • Expensive printhead • Expensive platform • Limited materials

Machine Choc Creator[33] Food Jetting Printer[2] Chefjet[34] Foodjet[32]

Company Choc Edge TNO 3D Systems De Grood Innovations

* The printing resolution is determined by nozzle diameter and/or powder size.

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A secondary material was utilized to support the fa-brication[35] and was removed after fabrication. Figure 6 shows two examples of multi-printhead food print-ing samples fabricated by our group at the National University of Singapore. The basic materials in this biscuit recipe consist of flour, butter, sugar and egg white. Food dyes are used to color the same recipe for different layers and patterns.

One challenge in multiple material printing is that multi-material may generate multi-scale ingredients after processing. Gray[2] proposed using electrospin-ning to produce multiple food sub-components at a micro-scale and further assemble them into mul-ti-component composite structures. This is a new so-lution to shape non-traditional food materials under multi-scale into appealing edible structures.

Figure 6. (A) Multi-material food design (B) Fabricated food samples

3.3 Mixing Techniques

Even with multiple printheads, it is not possible to develop a platform compatible with all food material printing. An alternative solution is to combine and mix a small group of ingredients to produce a relatively large material matrix. Two types of mixing techniques are explored to vary material composition and create more combinations of flour-based semi-solid viscoe-lastic materials. They are, namely, the static and agi-tated mixing techniques.

The static mixing fully relies on the driving force from material feeding and friction force between ma-terials and the mixer’s built-in structure. It comes as a static mixer concept for two-part epoxy adhesive resin mixing and dispensing. This technique is suitable for a continuous food flow mixing. However, a few tech-nical issues need to be overcome like consistency of food flow inside a helical structure, and the associated cleaning process for food residue within the structure.

The agitated mixing can adjust mixing ratios dy-namically so that the extruded food materials can con-tinuously change color or composition. Millen[15] de-signed two rigs for agitated mixing: oscillating mixing from periodic motion in a linear way, and conical sur-face mixing with a large contact area and friction force. The former achieved an acceptable result in two color mixing experiments. With further improvement, they can be more appropriate for discontinuous food flow mixing.

4. 3D Food Printing Impacts on Mass Custo-mization

Food printers introduce artistic capabilities to fine dining and extend mass customization capabilities to the industrial culinary sector. They also provide a re-search tool to manipulate food structure at multiple scales. Many players are active in food printing area such as 3D Systems, Choc Edge, and they are competing with each other using different technolo-gies and focuses for potential market opportuni-ties[2,32–34]. From a research perspective, TNO is a leading organization on nutritional customization[2]. 3D Systems is making a great effort to commercialize the powder bed food printer (Chefjet) and an extrusion base chocolate printer with Hershey[34]. Even though these food printing technologies are still under devel-opment, it is important to understand their core value, market applications, and potential impact on people’s lifestyle.

4.1 Professional Culinary in Daily Life

With a 3D food printing platform, designs from culi-nary professionals can be fabricated at any place by downloading the original data files. Users can repro-duce an original work by importing the corresponding fabrication files that carry culinary knowledge and artistic skills from chefs, nutrition experts, and food designers. After downloading design files, the prod-ucts can then be built in front of the customers using their personal 3D food printer. It is a new context of household product making, which would be impossi-ble to achieve using the existing methods.

4.2 Customized Food Design

Most of the food manufacturing techniques are devel-oped for mass production, while food creativity and customization on shapes, structures, and flavors are usually sacrificed. Food printing provides a platform for consumer experimentation with food forms and

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flavors[31]. It could offer more freedom for home users and designers to customize chocolate shaping[13,17,27]

and personalize full-color images onto solid food for-mats[23]. Figure 7 shows some customized food piece samples fabricated by our group.

4.3 Personalized Nutrition

Besides general nutritional preferences, in the recent years there has been a lot of emphasis on personalized nutrition corresponding to individual’s health status and body-type requirements[36]. When food printing is integrated with a nutrition model, users can calculate the exact data of calories and other ingredients of fa-bricated products, and provide a precise understanding of nutritional distribution. They can control their diet by selecting ingredients and corresponding fabrication parameters via a user interface. Hence, food printing provides a convenient way to digitize people’s nutri-tion and energy intake and offer a better control of in-dividual dietary. Personalized nutrition in food prod-ucts can be determined according to online informa-tion on nutritional content, personal, and social prefe-rences. Of course, there is a need for tailoring food ingredients, even with well-known material properties, to specific formulations under each fabrication.

Figure 8 shows a schematic diagram on how to personalize nutrition in food printing.

First, a nutrition profile for various contents is sug-gested based on the requirements from different user

groups. Then, a fabrication planning is developed based on recipe design, printing volume, 3D model design, and flavor selection. A key factor here is to adjust recipe design and printing volume control to achieve the listed contents on the nutrition profile. Thus, personalized nutrition can be realized in food printing.

4.4 Customized Food Supply Chain

Food printing targets a build-to-order strategy with higher production efficiency and lower overriding cost. Under an e-commerce platform, consumers may con-figure or transact food designs and fabricate physical products using a nearby production facility. To achieve zero lead-time from design to market, plenty of innovative food design websites and mobile apps can assist users on design and order customized food products. All of them will result in a great change in customized food supply chains, reduce the distribution costs, simplify customized food service, and bring products to consumers in a shorter time. A description of this new, customized food supply chain is shown in Figure 9. It starts with customers searching for an online food design platform based on their needs, and selecting a food design. The corresponding design data is transferred to a neighborhood Printing Service Bureau. The selected food designs are fabricated at this Bureau and are eventually delivered to the cus-tomers.

Figure 7. Customized food design and fabrication samples

Figure 8. Customized food with personalized nutrition

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Figure 9. Customized food supply chain

4.5 Food Processing Technologies

Most of the food processing technologies associated with chemical and physical changes may not match the 3D printing process. This applies to composition (ingredients and their interactions), structure, texture, and taste. Ingredient formulations with varied combi-nations and fabrication conditions can generate vari-ous textures in products, which may go beyond a ma-nageable level. Also, printing material property should be rigid and strong enough to support the weight of subsequently deposited layers. In other words, conventional food processing technologies are unlikely to fit into such a complicated scenario, and they should be reformulated, such as pre-conducting some processes (e.g., gluten formation and leavening) and replacing remaining processes (e.g., shaping and baking).

4.6 Process Model and Digitalization

To model the relationship between inputs and outputs, data quantification for each process (ingredients metering, mixing, printing, baking, etc.) and commu-nication protocols between different functions or pro-cesses should be established. Key process parameters such as temperature, moisture, and food properties (such as density, thermal, electrical conductivity, pri-nting viscosity, and permeability) are often coupled. It is crucial to digitalize a comprehensive fabrication into steps and combine them together to formulate a simulation model for manipulation. The data on food properties can be obtained from measurement, computerized database, handbook and theoretical calculations. Since food properties often vary from batch to batch, this simulation model should be able to predict the result of a particular for a range of proper-ties. It can also calculate the total amount of materials required to construct the final products, the construc-tion time, as well as calorie intake.

4.7 Innovative Food Products

Buddhist cuisine applies soy-based or gluten-based

materials for cooking meat analogue or mock meat dishes for vegetarians and Buddhists, which taste very similar to meat. The research from Lipton[21] also proved the concept of creating a wider range of tex-tures and tastes by mixing small group of hydrocollo-ids and flavor additives. In other words, it is feasible to create a wide range of food items with very similar taste and shape by using a limited number of raw ma-terials/ingredients. If such knowledge is embedded into the food printing process, more innovative food products and unique dining experiences can be created.

5. Future Work and Conclusion

3D food printing has demonstrated its capability of making personalized chocolates and producing simple homogenous snacks. However, these applications are still primitive with limited internal structures or monotonous textures. To achieve consistency in food fabrication, it is necessary to systematically investigate printing materials, platform designs, printing technol-ogies, and their influences on food fabrication. A process model is expected to link design, fabrication, and nutrient control together. With the development of an interactive user interface, food printers may become a part of an ecology system where networked machines can order new ingredients, prepare favorite food on demand, promote user's creativity, and even collaborate with doctors to promote healthier diets.

Food printing may exert a significant influence on various types of food processing. It provides design-ers/users with enhanced and unprecedented capability to manipulate forms and materials. This versatility, applied to domestic cooking or catering service, can improve the efficiency to deliver high quality and freshly-prepared food products to consumers with personalized nutrition. It is also capable of creating new flavors, textures and shapes to provide entirely new and unique eating experiences.

Conflict of Interest and Funding

No conflict of interest was reported by the authors.

Jie Sun, Zhuo Peng, Liangkun Yan, et al

International Journal of Bioprinting (2015)–Volume 1, Issue 1 37

This research is supported by the Singapore National Research Foundation under its International Research Center Keio-NUS CUTE Center @ Singapore Fund-ing Initiative and administered by the IDM Program Office. It is also partially sponsored by the Jiangsu Province Science and Technology Support Program, China under Grant No. BE2013057.

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