Food Printing Research Articles

Quantification of fracture mechanics with digital image correlation guides the infill design of 3D-printed snack bars with modulated flexural properties

ABSTRACT The ability to design complex infill patterns is unique for 3D food printing to modulate food texture on top of other factors such as processing parameters and structural porosity. This study systematically investigated the impact of infill designs on the flexural properties of 3D-printed snack bars made from pea ingredients. Three-point bending tests revealed that increasing infill angle from 30 to 90 degree resulted in a larger flexural strength but a smaller flexural elongation of the 3D-printed snack bars. However, crossed layer structures did not improve the flexural properties of the samples. Digital image correlation revealed deformation behaviour and fracture propagation of 3D-printed snack bars during mechanical tests. Using the strain maps generated, the designs of the 3D-printed snack bars were modulated to achieve desired flexural properties. Overall, this study shows that it is feasible to customise 3D-printed food texture while maintaining its total calorie, by modifying the infill design.

Rheology of plant protein–polysaccharide gel inks for 3D food printing: Modeling and structure–property relations

Plant protein–polysaccharide composite hydrogels and emulsion gels are attractive materials for production of edible inks for 3D food printing. Their ability to satisfy the printability requirements is conventionally evaluated in small- and large-amplitude oscillatory shear tests. A model is derived that describes experimental data in linear and nonlinear rheological tests on protein gels in a unified manner. The model is based on the population-balance approach and involves a reasonably small number of adjustable parameters. Fitting observations on soy protein isolate–xanthan gum, peanut protein–gellan gum, peanut protein–carrageenan, pea protein–carrageenan and pea protein isolate–flaxseed gum gels demonstrates that material parameters evolve consistently with composition of the gels. The governing equations describe adequately the effects of pH and ionic strength of aqueous solutions on the mechanical properties of the gels and predict the stress–strain Lissajous curves and the crossover amplitudes for transition from the solid-like to fluid-like response. Based on the analysis of observations in large-amplitude oscillatory tests with various frequencies, a mechanism is proposed for transition from the type-I (strain thinning) to type-III (weak strain overshoot) response of protein–polysaccharide gels.

Optimising printing fidelity of the single-nozzle based multimaterial direct ink writing for 3D food printing

ABSTRACT Single-nozzle based multimaterial direct ink writing enables voxel-based fabrication with superior printing efficiency than multi-nozzle protocol. This is attractive for food 3D printing process where efficiency matters for its application. However, for single-nozzle based process, the presence of residual material in the shared channel can affect its printing fidelity. In this study, we propose a path planning algorithm that can address this issue by incorporating (i) advance distance to compensate the extrusion delay when switching materials, and (ii) in-process printhead motion adjustments to stabilise the extrusion process. Our approach demonstrated a substantial improvement in printing fidelity, where the switching point offset was reduced to ±0.5 mm. Similarly, the unstable extrusion behaviours (bulging and necking) during switching materials were suppressed, where the printing fidelity was improved by 27 ± 5% (bulging) and 19 ± 3% (necking) respectively. Additionally, we provide an open-source slicing programme that empowers users to implement the above two algorithms.

Multi-material Direct Ink Writing 3D Food Printing using Multi-channel Nozzle

This paper describes a method for multi-material 3D food printing using a multi-channel nozzle in direct ink writing (DIW) with rapid ink switching. Existing methods for multi-material food printing rely on independently controlled syringes, posing challenges in (1) aligning more than one type of food inks and (2) creating a seamless continuous food filament with different materials. To overcome this limitation, we developed a method using a Y-junction nozzle for seamless ink switching. The use of two inks possessing different rheological properties may result in the backflow of the higher-yield-stress fluid into the channel of the lower-yield-stress fluid, which was addressed by designing the channel sizes to limit the backflow. We successfully demonstrated continuous printing of two food inks exhibiting a yield stress difference on the order of > 102. Real-time switching of the materials can delay deposition at the intended location, which was overcome by introducing an offset distance to the toolpath, resulting in a 74% reduction in print errors. Lastly, we demonstrated the Y-junction nozzle for co-laminar extrusion of two food materials, enabling anisotropic arrangements in 3D food objects. Our approach applies the Y-junction nozzle for multi-material 3D food printing, with broad applicability to various edible inks.

Consumer preference and willingness to pay for 3D-printed chocolates: A discrete choice experiment

This study explores the emerging field of 3D food printing, specifically examining consumer preferences for 3D-printed chocolate bars. While 3D printing has revolutionized various industries, the consumer acceptance of 3D-printed food remains a relatively underexplored topic. A discrete choice experiment was conducted to investigate consumer preferences and willingness to pay for 3D-printed chocolate bars in the UK. Key attributes included in the study were price, chocolate type, and the use of 3D printing technology. Using a mixed logit model, preference heterogeneity was assessed, revealing a general inclination towards 3D-printed chocolates, with an estimated increase in willingness to pay of £0.21 per 100 g. Furthermore, the influence of individual (participants’) characteristics, such as age, gender, prior knowledge of 3D food printing, and food technology neophobia, on perceived benefits associated with this technology and willingness to pay was also explored, using a structural equation modeling analysis. The results indicated that only perceived hedonic benefits, such as improved texture, positively impacted the willingness to pay, while food technology neophobia acted as a significant barrier. The results of this study therefore contribute valuable insights into the consumer acceptance of 3D-printed foods, specifically chocolates, highlighting potential avenues for market adoption and emphasizing the importance of effective communication in shaping consumer attitudes toward novel food processing technologies.

The effect of 3D printing speed and temperature on transferability of Staphylococcus aureus and Escherichia coli during 3D food printing

The current study aimed to determine if the 3D-printing speed and temperature would impact the transferability of foodborne pathogens from the stainless-steel (SS) food cartridge to the 3D-printed food ink. Staphylococcus aureus and Escherichia coli were inoculated onto the interior surface of the SS food cartridges. Subsequently, a model food ink was extruded with a recommended macronutrient contribution of 55.8, 23.7, and 20.5% of carbohydrates, proteins, and fat, respectively. The impact of 3D-printing temperatures and speeds on transfer rates was analysed using a Two-Way ANOVA. S. aureus was transferred more from the cartridge to the food ink with a population of 3.39, 2.98, and 3.09 log CFU/g compared to 2.03, 2.06, and 2.00 log CFU/g for E. coli at 2000, 3000, and 4000 mm/s printing speed, respectively, at 25 °C. A Kruskal-Wallis Test was employed to investigate the effect of different speeds and temperatures on the transferability of S. aureus and E. coli. Speed was the main factor affecting S. aureus transferability, while temperature (25 and 50 °C) had the greatest impact on E. coli transferability. This research seeks to advance the understanding of 3D-printing parameters in pathogen transferability and help the food industry move towards this technology's quick and safe adoption.

Tulane Virus Persistence and Microbial Stability in 3D Food Ink under Various Storage Conditions: A Pre- and Post-Printing Analysis

3D food printers facilitate novel customization of the physicochemical properties of food. This study aimed to investigate the impact of storage conditions on the inactivation of the human norovirus surrogate, Tulane virus (TuV), within 3D printed foods. TuV-inoculated protein cookie food ink (∽ 4 log PFU/g) was distributed into 18 3D food printer capsules (50 g each); half immediately underwent extrusion. Storage of the capsules and printed food products at 20 °C (0, 6, 12, and 24 h), 4 °C (0, 1, 3, and 5d), and − 18 °C (0, 1, 3, and 5d) was completed before analysis for TuV via plaque assays in addition to aerobic plate count, yeast and mold counts, and pH and water activity (aw) measurements. A significant 3-way interaction effect was observed between time, temperature, and storage method (capsule/print) (p = 0.006). Significant findings include: (1) A greater reduction in virions was observed in capsules after 24 h at 20 °C and (2) a substantial reduction in virions at 4 °C from day 0 to day 1 was observed, independent of storage method. Microbial indicators remained steady across temperatures, with storage temperature significantly impacting pH and aw. A significant two-way interaction effect (p = 0.006) was found between microorganism type (yeast/aerobic counts) and temperature. This research seeks to provide insights for the food industry and regulatory bodies in crafting guidelines for the safe storage and handling of 3D printed foods and inks.

Pea starch-based oleogels based on capillary water crosslinking: Physicochemical properties and 3D printing performance

The strong hydrophilicity of native starch limits its application as an oil gelling agent. In this study, starch-based oleogels were created by using water to form capillary crosslinks between starch granules dispersed in oil. Initially, we prepared pea starch-soybean oil gels containing a range of starch and water contents. The rheological properties, oil holding capacity, thermal stability, structural characteristics, and 3D printing performance of these oleogels were then evaluated. In addition, the impact of a thermal treatment on the properties of these oleogels was also examined. Increasing the starch and water content significantly increased the rheological properties and oil holding capacity (13.37%) of the oleogels, which was attributed to the formation of a stronger starch granule network in the oil phase held together by capillary forces. In addition, the oil holding capacity of the oleogels increased appreciably after the thermal treatment, which was mainly attributed to swelling of the starch granules. Oleogels with good 3D food printing performance could be produced by optimizing their starch and water content. This study provides valuable insights into the formulation of starch-based oleogels for 3D printing applications, which may be useful as solid fat substitutes in the food industry.

Three dimensional (3D)‐printed foods: A review of recent advances in their ingredients, printing techniques, food printers, post‐processing methods, consumer acceptance and safety

AbstractThree‐dimensional food printing (3DFP) involves layer‐by‐layer deposition of food materials to transform a part model into a food product. With this cutting‐edge food processing technology, food's acceptability, among others, can be enhanced, consequently contributing to food security. This review focuses on 3D‐printed foods (3DPFs), with an overview of 3DPFs, describing various printing techniques and the differences between them in terms of the principles used, and the food fabricated. This review also thoroughly elucidates the various kinds of 3D‐printable materials, functional ingredients, and the health advantages of using them to obtain 3DPFs. The consumer acceptance and safety of 3DPFs, research drawbacks, and promising aspects related to 3DFP are also explicated in this review. As the food industry looks for ways to reduce waste and boost the production of individualized and customized foods, 3D printing of foods is a sustainable way of food production for now and the future.Practical applicationsAdopting 3D food printing in the food industry can help minimize manufacturing costs while providing a variety of food whose designs are customizable, whose nutrients can be digitalized, and which can satisfy individuals' specific dietary requirements. With much more recent developments in novel ingredients, printing technologies, and food printers, post‐processing techniques, among others, this technology can significantly contribute to ensuring food security.

Nutritional Fuelling for Microgravity Environment of Space Missions

Abstract: Since the beginning of space missions, the food systems have undergone a sea change with prolonged manned missions and permanent space habitats. We have a better understanding of physiological changes which happen in humans in space and help in adaptation to the space environment. Yet, much remains underexplored and warrants further research. Space missions today involve a considerable number of individuals operating in a microgravity environment for both short and long periods. The provision of food for such missions and managing the physio-pathological changes that affect nutritional requirements continue to be challenging. Food systems (food and beverages) used during every program to date have been shelf‐stable and were composed primarily of rehydratable or thermostabilized food items. Such foods usually have a lower hedonic value than fresh or frozen foods. Consequently, a reliable food system must provide a wide range of palatable and attractive foods as well as the tools to prepare them (through rehydration, heating, and cooling) to enhance the taste sensation of the crew. Adequate nutrition with easily accessible food is essential to this effort. To deliver nutritional recommendations to crew members for long-duration space missions, it is important to understand how nutritional status and general physiology are linked and affected by microgravity exposure. In view of this, it has been pointed out that nutritional countermeasures could rectify the physiological and behavioural anomalies during microgravity exposure. In this comprehensive narrative review, we have provided an overview of a few recent advances such as silkworm protein, good mood-vegan diet, 3-D food printing, and space garden’s produce for onboard support to food systems. It has also been found that exercise could be an addition to nutritional interventions. Areas of space exploration that require more in-depth research using ground-based bed rest models, as well as inflight microgravity conditions, are highlighted.

Addressing the safety of new food sources and production systems.

New food sources and production systems (NFPS) are garnering much attention, driven by international trade, changing consumer preferences, potential sustainability benefits, and innovations in climate-resilient food production systems. However, NFPS can introduce new challenges for food safety agencies and food manufacturers. Most food safety hazards linked to new foods have been identified in traditional foods. However, there can be some food safety challenges that are unique to new foods. New food ingredients, inputs, and processes can introduce unexpected contaminants. To realize the full potential of NFPS, there is a need for stakeholders from governments, the food industry, and the research community to collectively work to address and communicate the safety of NFPS products. This review outlines known food safety hazards associated with select NFPS products on the market, namely, plant-derived proteins, seaweeds, jellyfish, insects, microbial proteins, as well asfoods derived from cell-based food production, precision fermentation, vertical farming, and 3D food printing. We identify common elements in emerging NFPS regulatory frameworks in various countries/regions. Furthermore, we highlight current efforts in harmonization of terminologies, use of recent scientific tools to fill in food safety knowledge gaps, and international multi-stakeholder collaborations to tackle safety challenges. Although there cannot be a one-size-fits-all approach when it comes to the regulatory oversight for ensuring the safety of NFPS, there is a need to develop consensus-based structured protocols or workflows among stakeholders to facilitate comprehensive, robust, and internationally harmonized approaches. These efforts increase consumers' confidence in the safety of new foods and contribute toward fair practices in the international trade of such foods.

Carrageenan as a Potential Factor of Inflammatory Bowel Diseases.

Carrageenan is a widely used food additive and is seen as a potential candidate in the pharmaceutical industry. However, there are two faces to carrageenan that allows it to be used positively for therapeutic purposes. Carrageenan can be used to create edible films and for encapsulating drugs, and there is also interest in the use of carrageenan for food printing. Carrageenan is a naturally occurring polysaccharide gum. Depending on the type of carrageenan, it is used in regulating the composition of intestinal microflora, including the increase in the population of Bifidobacterium bacteria. On the other hand, the studies have demonstrated the harmfulness of carrageenan in animal and human models, indicating a direct link between diet and intestinal inflammatory states. Carrageenan changes the intestinal microflora, especially Akkermansia muciniphilia, degrades the mucous barrier and breaks down the mucous barrier, causing an inflammatory reaction. It directly affects epithelial cells by activating the pro-inflammatory nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) pathway. The mechanism is based on activation of the TLR4 receptor, alterations in macrophage activity, production of proinflammatory cytokines and activation of innate immune pathways. Carrageenan increases the content of Bacteroidetes bacteria, also causing a reduction in the number of short chain fatty acid (SCFA)-producing bacteria. The result is damage to the integrity of the intestinal membrane and reduction of the mucin layer. The group most exposed to the harmful effects of carrageenan are people suffering from intestinal inflammation, including Crohn disease (CD) and ulcerative colitis (UC).

Performance Analysis of ResNet50 and Inception-V3 Image Classification for Defect Detection in 3D Food Printing

In the future, 3D food printing may be a fruitful area for the food industry. The presence of this technology opens the public's eyes to a revolution in the food sector, where food processing is limited to the conventional. The existence of this technology will also make food production much more effective and efficient. However, there is a problem when the 3D Food Printing process is carried out; when object defects occur, there will be material waste. This research proposes deep learning-based defect detection for defect and non-defect objects. This model mainly uses CNN as a deep learning method. The dataset is taken from the image of the print process performed at the time of object creation to be trained and validated to check the effectiveness of the proposed model. The architecture used uses pre-trained CNN models namely Inception-V3 and ResNet50 with the hope of classifying images that have a higher viscosity of the material. Where the model has been tested with previous datasets and applied with 3D Food Printing datasets with a dataset division ratio of 85% which is training data and 15% is validation data. After testing the two proposed scenarios, the accuracy result obtained in the test model scenario 1, Inception-V3, is 84.62% and for the test model scenario 2, ResNet50, the accuracy is 93.83%. The outcomes also demonstrate that improved accuracy, loss, and classification time may be obtained by applying CNN in conjunction with data augmentation.

Optimization of the temperature profile of cake batter in an ohmic heating – assisted printing nozzle for 3D food printing applications

Abstract 3D printing of food has great potential for applications such as the design of customised food or the creation of innovative textures. However, printed products often do not retain their structure due to the composition of the material, especially in the case of cereal products. Cooking such products with a nozzle could be an alternative to meet this challenge. The objective of this work was to develop, with the help of a numerical model, a 3D cake batter printing nozzle in which ohmic heating is used for baking. The use of a temperature and shear rate dependent viscosity allowed the solidification of the batter during baking due to starch gelatinization. The numerical model made it possible to predict heterogeneity in temperature distribution. Optimization procedures were used to reach desired temperature profiles at the outlet of the nozzle, reducing by 17 % the electrical power used for heating and by 78 % the energy evacuated during cooling.

Additive Manufacturing: A Comprehensive Review.

Additive manufacturing has revolutionized manufacturing across a spectrum of industries by enabling the production of complex geometries with unparalleled customization and reduced waste. Beginning as a rapid prototyping tool, additive manufacturing has matured into a comprehensive manufacturing solution, embracing a wide range of materials, such as polymers, metals, ceramics, and composites. This paper delves into the workflow of additive manufacturing, encompassing design, modeling, slicing, printing, and post-processing. Various additive manufacturing technologies are explored, including material extrusion, VAT polymerization, material jetting, binder jetting, selective laser sintering, selective laser melting, direct metal laser sintering, electron beam melting, multi-jet fusion, direct energy deposition, carbon fiber reinforced, laminated object manufacturing, and more, discussing their principles, advantages, disadvantages, material compatibilities, applications, and developing trends. Additionally, the future of additive manufacturing is projected, highlighting potential advancements in 3D bioprinting, 3D food printing, large-scale 3D printing, 4D printing, and AI-based additive manufacturing. This comprehensive survey aims to underscore the transformative impact of additive manufacturing on global manufacturing, emphasizing ongoing challenges and the promising horizon of innovations that could further elevate its role in the manufacturing revolution.

An engineering approach to the 3D printing of K‐Carrageenan/konjac glucomannan hydrogels

SummaryAqueous solutions of Konjac glucomannan (KGM)/κ‐Carrageenan (κ‐C) of different ratios (1:2, 1:5, 1:8 and 1:10) and a fixed κ‐C content of 1.5%, were proposed as a new 3D food printing ink. Their thermo‐responsive behaviour was evaluated by temperature ramp rheological tests. This characterisation allowed for the evaluation of the synergistic effect between KGM and κ‐C and gave indications useful to the printing performance. Both elastic (G′) and loss (G″) moduli were found to increase by increasing the KGM concentration. Samples were printed by controlling the thermally reversible sol/gel transition occurring during the process. Direct pressure and flow rate measurements in the 3D printer were used to obtain the viscosity versus shear rate curves under processing conditions, useful to validate a scaling law relating the printing filament diameter to the relevant process and material properties (inks viscosity and printing pressure). The 3D printing performance of inks was evaluated by means of a novel, integrated score system. The results obtained indicate that aqueous mixtures of KGM/κ‐C can be successfully employed as a base for 3D printing food hydrogels. The use of the score system above outlined proved to be an easy yet efficient tool for the optimisation of the gel composition.

Improvement in 3D printability, rheological and mechanical properties of pea protein gels prepared by plasma activated microbubble water

Three-dimensional (3D) food printing is one of the emerging processing technologies that enables the construction of complex food structures and customization. Although various food ingredients have been explored for their 3D printability, pea protein is among the plant proteins that have not been studied extensively on its 3D printability, owing to its native inability to hold shape and structure following extrusion. This study investigated the effect of plasma activated microbubble (PAMB) treatment on the thermal gelation and 3D printability of pea protein isolate (PPI). PAMB treatments with different combinations of discharge gases (80% argon and 20% air, 90% argon and 10% air, 100% argon, and 100% air) were applied to prepare PPI suspensions. These suspensions were then heated at 85 °C for 30 and 60 min, followed by immediate cooling to prepare PPI gels. The viscoelastic measurements and mechanical properties of PPI gels indicated that this combined application was suitable for 3D printing, with a notable increase in storage modulus (G '), loss modulus (G '') and compressive stress in PPI-PAMB gels. The 3D printed PPI gels prepared using PAMB treatment exhibited better structure retention, resistance to deformation, and stability during storage. The treatment using PAMB prepared by the combination of argon and air, i.e., 80% argon and 20% air and 90% argon and 10% air, resulted in PPI gels with better rheological properties, mechanical stability, and 3D printability. Freeze drying was investigated as a possible post-3D printing processing operation to enhance the shelf life and storage stability of 3D printed PPI gels. The moisture content, water activity, and textural properties of the freeze-dried 3D printed PPI were investigated.

3D printing of rice starch incorporated peanut protein isolate paste: Rheological characterization and simulation of flow properties

This study investigates the viscosity and creep behavior of peanut protein isolate (PPI) paste incorporated with rice starch (RS) for potential applications in 3D printing. The change in flow properties during the 3D printing was also studied by numerical simulation. The paste exhibited shear-thinning behavior with yield stress. The pressure predicted from the Herschel-Bulkley model showed higher values than those derived from the Power-Law model. The PPI and RS levels had negligible influence on velocity and shear rate; however, they showed greater dependence on the inflow rate. The fractional element model described the creep data well (R2 > 0.9). The addition of PPI resulted in increased viscosity, simulated pressure, and mean extrusion force, with similar effects observed for RS, except at higher PPI levels. Furthermore, the 3D-printed objects revealed that deformations were pronounced at low concentrations of PPI and RS, while resolution suffered when employing higher concentrations of PPI and RS. Industrial relevanceUsing peanut protein isolate, a plant-based high protein ingredient in 3D printing, reduces energy consumption, thereby reducing carbon footprints, offers improved functional properties, and diversifies dietary options by offering an alternative protein source from peanuts. The printing is influenced by the rheological properties of food ink. Thus, knowing the rheological properties of food ink can help researchers and industries to prepare food inks with desired properties. The observations of numerical simulation of this work have the potential to offer practical insights for designing 3D printing systems. In summary, this work has the potential to aid in improving and developing food ink for 3D printing, hence enhancing the performance of extrusion-based 3D food printers.

SCOBY: an alternate solution to develop cheap and nutritious food by food layered manufacturing (FLM)

PurposeIn pursuit of affordable and nutrient-rich food alternatives, the symbiotic culture of bacteria and yeast (SCOBY) emerged as a selected food ink for 3D printing. The purpose of this paper is to harness SCOBY’s potential to create cost-effective and nourishing food options using the innovative technique of 3D printing.Design/methodology/approachThis work presents a comparative analysis of the printability of SCOBY with blends of wheat flour, with a focus on the optimization of process variables such as printing composition, nozzle height, nozzle diameter, printing speed, extrusion motor speed and extrusion rate. Extensive research was carried out to explore the diverse physical, mechanical and rheological properties of food ink.FindingsAmong the ratios tested, SCOBY, with SCOBY:wheat flour ratio at 1:0.33 exhibited the highest precision and layer definition when 3D printed at 50 and 60 mm/s printing speeds, 180 rpm motor speed and 0.8 mm nozzle with a 0.005 cm3/s extrusion rate, with minimum alteration in colour.Originality/valueFood layered manufacturing (FLM) is a novel concept that uses a specialized printer to fabricate edible objects by layering edible materials, such as chocolate, confectionaries and pureed fruits and vegetables. FLM is a disruptive technology that enables the creation of personalized and texture-tailored foods, incorporating desired nutritional values and food quality, using a variety of ingredients and additions. This research highlights the potential of SCOBY as a viable material for 3D food printing applications.

Lutein encapsulation into dual-layered starch/zein gels using 3D food printing: Improved storage stability and in vitro bioaccessibility

The ability of 3D printing to encapsulate, protect, and enhance lutein bioaccessibility was investigated under various printing conditions. A spiral-cube-shaped geometry was used to investigate the effects of printing parameters, namely zein concentration (Z; 20, 40, and 60 %) and printing speed (PS; 4, 8, 14, and 20 mm/s). Coaxial extrusion 3D printing was used with lutein-loaded zein as the internal flow material, and corn starch paste as the external flow material. The viscosities of the inks, microstructural properties, storage stability, and bioaccessibility of encapsulated lutein were determined. The sample printed with a zein concentration of 40 % at a printing speed of 14 mm/s (Z-40/PS-14) exhibited the best shape integrity. When lutein was entrapped in starch/zein gels (Z-40/PS-14), only 39 % of lutein degraded after 21 days at 25 °C, whereas 78 % degraded at the same time when crude lutein was studied. Similar improvements were also observed after storing at 50 °C for 21 days. Furthermore, after simulated digestion, the bioaccessibility of encapsulated lutein (9.8 %) was substantially higher than that of crude lutein (1.5 %). As a result, the developed delivery system using 3D printing could be an effective strategy for enhancing the chemical stability and bioaccessibility of bioactive compounds (BCs).