Investigation on lemon juice gel as food material for 3D printing and optimization of printing parameters

Moderation-excess interactions of epigallocatechin gallate and CaCl2 modulate the gelation performance of egg white transparent gels

In this study, the moderation-excess interaction of epigallocatechin gallate (EGCG) and calcium ions (Ca2+) to the gelation performance of transparent egg white protein (EWP) gel (EWG) was explored. The oxidation of EGCG introduced a yellowish-brown EWG, whereas the weakening of Ca2+ ionic bonds caused a notable reduction in the hardness of EWG, from 120.67 g to 73.57 g. Achieving the optimal EGCG-to-Ca2+ ratio in EWG conferred enhanced water-holding capacity to 86.98%, while an excess of EGCG attributed to the creation of a three-dimensional structure within the void "walls". The elevated presence of EGCG influenced the ionic bonds and hydrophobic interactions, thereby presenting a moderate-excess relationship with sulfhydryl and disulfide bonds, β-sheet, and α-helical structures. Notably, EGCG reduced the digestibility of EWG to 50.06%, while concurrently fostering the creation of smaller particle sizes. This study provides a scientific basis for the controllable preparation and quality regulation of transparent EWG.

Influence of carboxymethyl cellulose on the stability, rheology, and curcumin bioaccessibility of high internal phase Pickering emulsions

Recently, there has been a focus on using biopolymer-based particles to stabilize high internal phase Pickering emulsions (HIPPEs) due to the notable advances in biocompatibility and biodegradability. In this work, the complex particles of peanut protein isolate and carboxymethyl cellulose (CMC) with various substitution degrees (DS; 0.7 and 0.9) and weight average molecular weights (Mw; 90, 250, and 700 kDa) were prepared and characterized as novel stabilizers. For the obtained four types of morphologically distinct particles, the complex particles formed by CMC (0.9 DS and 250 kDa) showed cluster structures with an average size of 1.271 μm, equally biphasic wettability with three-phase contact angles of 91.5°, and the highest diffusion rate at the oil-water interface. HIPPEs stabilized by these particles exhibited more elastic behavior due to the smaller tanδ and higher viscosity, as well as excellent thixotropic recovery properties and stability against heating, storage, and freeze-thawing. Furthermore, confocal laser scanning microscopy verified that these particles formed a dense interfacial layer around the oil droplets, which could resist flocculation and coalescence between oil droplets during in vitro digestion. The improved bioaccessibility of curcumin-loaded HIPPEs made these delivery systems potentially apply in functional foods.

Personalized nutrition with 3D-printed foods: A systematic review on the impact of different additives

Three-dimensional (3D) printing is one of the world's top novel technologies in the food industry due to the production of food in different conditions and places (restaurants, homes, catering, schools, for dysphagia patients, and astronauts' food) and the production of personalized food. Nowadays, 3D printers are used in the main food industries, including meat, dairy, cereals, fruits, and vegetables, and have been able to produce successfully on a small scale. However, due to the expansion of this technology, it has challenges such as high-scale production, selection of printable food, formulation optimization, and food production according to the consumer's opinion. Food additives (gums, enzymes, proteins, starches, polyphenols, spices, probiotics, algae, edible insects, oils, salts, vitamins, flavors, and by-products) are one of the main components of the formulation that can be effective in food production according to the consumer's attitude. Food additives can have the highest impact on textural and sensory characteristics, which can be effective in improving consumer attitudes and reducing food neophobia. Most of the 3D-printed food cannot be printed without the presence of hydrocolloids, because the proper flow of the selected formulation is one of the key factors in improving the quality of the printed product. Functional additives such as probiotics can be useful for specific purposes and functional food production. Food personalization for specific diseases with 3D printing technology requires a change in the formulation, which is closely related to the selection of correct food additives. For example, the production of 3D-printed plant-based steaks is not possible without the presence of additives, or the production of food for dysphagia patients is possible in many cases by adding hydrocolloids. In general, additives can improve the textural, rheological, nutritional, and sensory characteristics of 3D printed foods; so, investigating the mechanism of the additives on all the characteristics of the printed product can provide a wide perspective for industrial production and future studies.

3D printing: trends and approaches toward achieving long-term sustainability in the food industry

Global food security has recently been under serious threat from the rapid rise in the world's population, the problems brought on by climate change, and the appearance of new pandemics. As a result, the need for novel and innovative solutions to solve the existing problems and improve food sustainability has become crucial. 3D printing is expected to play a significant role in providing tangible contributions to the food industry in achieving sustainable development goals. The 3D food printing holds the potential to produce highly customized food in terms of shape, texture, flavor, structure and nutritional value and enable us to create new unique formulations and edible alternatives. The problem of whether the cost of the printed meal and 3D printing itself can be sustainably produced is becoming more and more important due to global concerns. This review intends to provide a comprehensive overview of 3D printed foods with an overview of the current printing methodologies, illustrating the technology's influencing factors, and its applications in personalized nutrition, packaging, value addition, and valorization aspects to fully integrate sustainability concerns thus exploring the potential of 3D food printing.

Characterization of Antioxidant Bioactive Compounds and Rheological, Color and Sensory Properties in 3D-Printed Fruit Snacks

The influence of wheat starch (6%, 8% and 10%, w/w) and a 3D printing program (program 1 vs. program 2) on the content of bioactive compounds, antioxidant capacity, color parameters and rheological and sensory properties was investigated in 3D strawberry and strawberry tree fruit snacks. Increasing the starch content led to a decrease in the content of almost all the bioactive compounds, while it had no effect on the antioxidant capacity. The printing program had no significant effect on the bioactive compounds (except hydroxycinnamic acids), antioxidant capacity and color parameters. A higher starch content improved the strength of the sample but had no effect on the mechanical properties. Smaller particles with a higher starch content improved the stability of the sample. In contrast to the programs, varying the starch content had a significant effect on all the color parameters except the a* values. Eight different sweeteners in two different concentrations were used for the sensory evaluation of the 3D-printed snacks. The variations in sweetener content only affected the sweet and harmonious taste. In summary, this study confirms the great potential of fruit bases for the production of 3D-printed snacks with excellent biological and rheological properties, which can be a step toward personalized food with the addition of sweeteners.

Using waste biomass to produce 3D-printed artificial biodegradable structures for coastal ecosystem restoration

The loss of ecosystem functions and services caused by rapidly declining coastal marine ecosystems, including corals and bivalve reefs and wetlands, around the world has sparked significant interest in interdisciplinary methods to restore these ecologically and socially important ecosystems. In recent years, 3D-printed artificial biodegradable structures that mimic natural life stages or habitat have emerged as a promising method for coastal marine restoration. The effectiveness of this method relies on the availability of low-cost biodegradable printing polymers and the development of 3D-printed biomimetic structures that efficiently support the growth of plant and sessile animal species without harming the surrounding ecosystem. In this context, we present the potential and pathway for utilizing low-cost biodegradable biopolymers from waste biomass as printing materials to fabricate 3D-printed biodegradable artificial structures for restoring coastal marine ecosystems. Various waste biomass sources can be used to produce inexpensive biopolymers, particularly those with the higher mechanical rigidity required for 3D-printed artificial structures intended to restore marine ecosystems. Advancements in 3D printing methods, as well as biopolymer modifications and blending to address challenges like biopolymer solubility, rheology, chemical composition, crystallinity, plasticity, and heat stability, have enabled the fabrication of robust structures. The ability of 3D-printed structures to support species colonization and protection was found to be greatly influenced by their biopolymer type, surface topography, structure design, and complexity. Considering limited studies on biodegradability and the effect of biodegradation products on marine ecosystems, we highlight the need for investigating the biodegradability of biopolymers in marine conditions as well as the ecotoxicity of the degraded products. Finally, we present the challenges, considerations, and future perspectives for designing tunable biomimetic 3D-printed artificial biodegradable structures from waste biomass biopolymers for large-scale coastal marine restoration.

Investigation on 3D printing of shrimp surimi under different printing parameters and thermal processing conditions

Improving the printing accuracy and stability of shrimp surimi and finding appropriate printing parameters and suitable thermal processing method can help to develop high value-added 3D printing products of shrimp surimi. It was found that in order to make the 3D printing products of shrimp surimi have higher printing adaptability (printing accuracy and printing stability reach more than 97%), by choosing nozzle diameter of 1.20 mm and setting the printing height of the nozzle to 2.00 mm, the layers of the printed products were better fused with each other, and the printing accuracy of the products could be greatly improved; there was no uneven discharge and filament breakage when the nozzle moved at the speed of 30 mm/s; and the products were internally compact and had good stability when the printing filling rate was 80%. In addition, the deformation rates of steamed, boiled and deep-fried shrimp surimi products were significantly higher than those of oven-baked and microwaved shrimp surimi products (P < 0.05). Microwave heating had a greater effect on the deformation and color of shrimp surimi products, and was not favored by the evaluators. In terms of deformation rate, sensory score, and textural characteristic, the oven-baked thermal processing method was selected to obtain higher sensory evaluation scores and lower deformation rates of shrimp surimi 3D printed products. In the future, DIY design can be carried out in 3D printing products of shrimp surimi to meet the needs of different groups of people for modern food.

Construction of 3D-Printed Sodium Alginate/Chitosan/Halloysite Nanotube Composites as Adsorbents of Methylene Blue

In this study, sodium alginate/chitosan/halloysite nanotube composites were prepared by three-dimensional printing and characterized in terms of morphology, viscosity, thermal properties, and methylene blue (MB) adsorption performance. The high specific surface area and extensively microporous structure of these composites allowed for effective MB removal from wastewater; specifically, a removal efficiency of 80% was obtained after a 60 min treatment at an adsorbent loading of 1 g L-1 and an MB concentration of 80 mg L-1, while the maximum MB adsorption capacity equaled 376.3 mg g-1. Adsorption kinetics and isotherms were well described by quasi-second-order and Langmuir models, respectively. The composites largely retained their adsorption performance after five adsorption-desorption cycles and were concluded to hold great promise for MB removal from wastewater.

Development of 3D printed k-carrageenan-based gummy candies modified by fenugreek gum: Correlating 3D printing performance with sol-gel transition

Temperature-responsive inks were formulated using k-carrageenan, fenugreek gum (FG), rose extracts, and sugar, of which the first two were used as the gelling agents. The interactions among components in these mixed ink formulations were investigated. Sol-gel transition and rheological properties of these inks were also correlated with extrusion, shape formation, and self (shape)-supporting aspects of 3D printing. Results indicated that incorporating FG increased inks' gelation temperature from 39.7 °C to 44.7-49.6 °C, affecting the selection of printing temperature (e.g., 0 % FG: 40 °C, 0.15 % FG: 45 °C, 0.3 % FG-0.6 % FG: 50 °C). Inks in solution states with lower viscosity (<5 Pa·s) were amenable to ensure their smooth extrusion through the tip of the printing nozzle. A shorter sol-gel transition time (approximately 100 s) during the shape formation stage facilitated the solidification of inks after extrusion. The addition of FG significantly (p<0.05) improved the mechanical properties (elastic modulus, hardness, etc.) of the printed models, which facilitated their self-supporting behavior. Low field nuclear magnetic resonance indicated that the inclusion of FG progressively restricted water mobility, consequently reducing the water syneresis rate of the mixed inks by 0.86 %-3.6 %. FG enhanced hydrogen bonding interactions among the components of these mixed inks, and helped to form a denser network.

Modulation of starch structure, swallowability and digestibility of 3D-printed diabetic-friendly food for the elderly by dry heating

Elderly people often experience difficulty in swallowing and have impaired regulation of the nervous system. Furthermore, their blood glucose level can rise easily after eating. Therefore, functional foods that are easy to swallow and can maintain blood glucose at a lower level have been an important research topic in recent years. In this study, 3D printing was combined with dry heating to modify the starch in white quinoa and brown rice to develop whole grain foods with Osmanthus flavor that meet the dietary habits of the elderly. The samples were tested for printability, swallowing performance, and in vitro digestion. The results showed that after dry heating, all samples had shear-thinning properties and could pass through the extrusion nozzle of the printer smoothly. Both white quinoa and brown rice showed improved printability and self-support compared to the control. B45 (white quinoa, dry heating for 45 min) and C45 (brown rice, dry heating for 45 min) had significant elasticity and greater internal interaction strength during swallowing to resist disintegration of food particles during chewing. B45, C30, and C45, conformed to class 4 consistency and were characterized by easy swallowing of the diet. Further, dry heating resulted in greater resistance to enzymatic degradation of white quinoa and brown rice starch, with overall in vitro digestibility lower than the control.

Undaria pinnatifida gel inks for food 3D printing are developed based on the colloidal properties of Undaria pinnatifida slurry and protein/colloidal/starch substances

Currently, people eat Undaria pinnatifida (UP) in a single way, and processing homogeneity is serious. However, UP has not gained any traction in the 3D printing industry to date. This study explored the incorporation of soy protein isolate (SPI), pea protein (PP), xanthan gum (XG), guar gum (GG), corn starch (CS), and potato starch (PS) into UP slurry liquid, the primary component of the study, to formulate a UP gel ink. The UP gel 3D printing ink system based on UP paste was established and characterized. The results show that hydrogen bonds are formed, and three-dimensional gel network structure is formed in all UP gel inks. UP gel inks containing high concentrations of SPI and GG exhibited good texture and rheological qualities and good 3D printing effect, with storage modulus (G') values of 8440.405 ± 3.893 and 8111.730 ± 3.585 Pa. The loss of modulus (G″) values were 1409.107 ± 3.524 and 1071.673 ± 3.669 Pa. Unfortunately, the properties of other UP gel inks are not suitable, resulting in poor 3D printing results. The food 3D printing method developed in this study provides valuable insights for expanding food 3D printing material choices and achieving high-value applications of UP.

The color/shape/flavor of yam gel with double emulsified microcapsules changed synchronously in 4D printing induced by microwave

The feasibility of 3D printing the color, aroma and shape changes of yam gel with microwave heating as stimulus and soybean protein isolate-chitosan-maltodextrin complex coacervated microcapsules rich in water-soluble betacyanin and rose essence as stimulus-response materials was discussed. The morphology of microcapsules presented irregular spherical structure, and the surface was relatively smooth and slightly concave. Microwave heating led to the gradual destruction of microcapsules in yam gel, releasing internal pigments and essence, and enhancing the redness and flavor of printed samples. The release of the water phase and oil phase of the microcapsules and the hot-spot expansion effect of the models made the 3D printed bird models bend and deform, realizing the deformation effect of "spreading of wings", which realized a three-response synchronous change in color, shape, and flavor of the printed samples within 45 s. In this study, a variety of 4D printed foods with synchronous changes in sensory characteristics were created, which increased sensory enjoyment on the basis of ensuring the nutritional needs of food.

Impact of Corn Starch Molecular Structures on Texture, Water Dynamics, Microstructure, and Protein Structure in Silver Carp (Hypophthalmichthys molitrix) Surimi Gel

This study systematically investigates the impact of corn starch molecular structures on the quality attributes of surimi gel products. Employing molecular analyses to characterize corn starch, three amylopectin fractions (A, B1, and B2), categorized by the degree of polymerization ranges (6 < X ≤ 12, 12 < X ≤ 24, and 24 < X ≤ 36, respectively) were specifically focused on. The surimi gel quality was comprehensively assessed through texture profile analysis, nuclear magnetic resonance, scanning electron microscopy, stained section analysis, and Fourier transform infrared spectroscopy. Results indicated the substantial volume expansion of corn amylopectin upon water absorption, effectively occupying the surimi gel matrix and fostering the development of a more densely packed protein network. Starch gels with higher proportions of A, B1, and B2 exhibited improved hardness, chewiness, and bound water content in the resultant surimi gels. The weight-average molecular weight and peak molecular weight of corn starch showed a strong positive correlation with surimi gel hardness and chewiness. Notably, the secondary structure of proteins within the surimi gel was found to be independent of corn starch's molecular structure. This study provides valuable insights for optimizing formulations in surimi gel products, emphasizing the significance of elevated A, B1, and B2 content in corn starch as an optimal choice for crafting dense, chewy, water-retaining surimi gels.

Strawberry tree fruits (Arbutus unedo L.): Bioactive composition, cellular antioxidant activity, and 3D printing of functional foods

The aim of this study was to investigate the use of Arbutus unedo L. fruits for the production of functional foods by three-dimensional printing (3DP). First, the biological activity of the fruits was investigated in vitro, followed by 3DP with different starch types and proportions using two 3DP programs. All 3DP samples were characterized for their bioactive, antioxidant, physicochemical and rheological properties. In terms of biological activity, the recommended daily dose of polyphenols from the aqueous extract of A. unedo can protect the integrity of DNA. Moreover, it could be useful as an antimicrobial agent. All 3DP parameters significantly affected bioactive compounds and antioxidant capacity. The 3DP products were found to be a good source of polyphenols (632.60 mg/100 g), among which condensed tannins were predominant (42 %). In conclusion, the fruits of A. unedo should be considered as a sustainable resource for the production of innovative functional foods with 3DP.

Elaboration of dimensional quality in 3D-printed food: Key factors in process steps

Three-dimensional (3D) printing has been applied to produce food products with intricate and fancy shapes. Dimensional quality, such as dimensional stability, surface smoothness, shape fidelity, and resolution, are essential for the attractive appearance of 3D-printed food. Various methods have been extensively studied and proposed to control the dimensional quality of printed foods, but few papers focused on comprehensively and deeply summarizing the key factors of the dimensional quality of printed products at each stage-before, during, and after printing-of the 3D printing process. Therefore, the effects of pretreatment, printing parameters and rheological properties, and cooking and storage on the dimensional quality of the printed foods are summarized, and solutions are also provided for improving the dimensional quality of the printed products at each step. Before printing, incorporating additives or applying physical, chemical, or biological pretreatments can improve the dimensional quality of carbohydrate-based, protein-based, or lipid-based printed food. During printing, controlling the printing parameters and modifying the rheological properties of inks can affect the shape of printed products. Furthermore, post-processing is essential for some printed foods. After printing, changing formulations, incorporating additives, and selecting post-processing methods and conditions may help achieve the desired shape of 3D-printed or 4D-printed products during cooking. Additives help in the storage stability of printed food. Finally, various opportunities have been proposed to regulate the dimensional properties of 3D-printed structures. This review provides detailed guidelines for researchers and users of 3D printers to produce various printed foods with the desired shapes and appearances.

From bytes to bites: Advancing the food industry with three-dimensional food printing

The rapid advancement of three-dimensional (3D) printing (i.e., a type of additive manufacturing) technology has brought about significant advances in various industries, including the food industry. Among its many potential benefits, 3D food printing offers a promising solution to deliver products meeting the unique nutritional needs of diverse populations while also promoting sustainability within the food system. However, this is an emerging field, and there are several aspects to consider when planning for use of 3D food printing for large-scale food production. This comprehensive review explores the importance of food safety when using 3D printing to produce food products, including pathogens of concern, machine hygiene, and cleanability, as well as the role of macronutrients and storage conditions in microbial risks. Furthermore, postprocessing factors such as packaging, transportation, and dispensing of 3D-printed foods are discussed. Finally, this review delves into barriers of implementation of 3D food printers and presents both the limitations and opportunities of 3D food printing technology.

Multivariate evaluation of the printing process on 3D printing of rice protein

The combination of printing parameters appropriately improves the printability of 3D-printed foods. In this regard, the present study aims to evaluate the effect of 3D printing process parameters on protein food generation. Printability of a cylinder 3 cm in diameter and 1 cm in height using a protein mixture of rice water and xanthan gum with a ratio of 30:70:0.5 was evaluated in an extrusion printer with an XYZ system. A ½ fractional factorial design was used with three factors: nozzle diameter (1.2 - 2.2 mm), layer height (1.0 - 2.0 mm), and print speed (20 - 50 mm/s). Each combination of factor levels was performed in triplicate for 12 runs plus three central points. Print time (min), sample weight, change in diameter (%), change in height (%), change in volume (%), mass flow rate (mg/s), appreciation (qualitative variable), and textural and rheology characters were obtained as response variables. The linear effects of the factors and combination factors were evaluated by analysis of variance. Additionally, a principal component analysis was performed to visualize the similarity between the observations and the relationship between the variables. The results showed that the layer height and nozzle diameter affect the printing accuracy concerning surface quality, shape stability, resolution, and layer layout. The nozzle with a diameter of 1.7 mm combined with speeds between 35 and 50 mm/s allowed the effects of overextrusion to be overcome, generating a better flow of the material. Low scores in the printability variable were related to low-speed values (20 mm/s) and a high nozzle diameter (2.2 mm), which generated higher deformations in the printed protein cylinder. Additionally, some printing conditions affected the textural and rheological characteristics, which allowed inferring that the capacity of the protein mass to store and recover energy in compression processes is conditioned by the printing parameters.

Investigation of 3D printing of toddler foods with special shape and function based on fenugreek gum and flaxseed protein

The practicability of using corn and flaxseed protein as printing inks for manufacture of printed products specifically designed for toddlers as a dysphagia diet with high precision and special shapes with addition of fenugreek gum (FGG) was investigated. 3D printing was used to process grains and dysphagia-compatible food (corn) into a dietary product with attractive appearance which was also easy to swallow. Rheological measurements shown that appropriate amount of flaxseed protein (FP, 0-10 %) can reduce the stickiness and yield strength of printing material. Based on FTIR measurements, FP weakened the hydrogen bond strength of inks, but it was still an important gradient for the formation of the ink suitable for precision 3D printing. The TPA results shown that the addition of FP (0-10 %) remarkably reduced both the stickiness and hardness of the ink. These results shown that compared with the control group, materials with FGG additions possessed higher printing accuracy and self-supporting ability. Ink with 5 % FP content exhibited the best printability and swallowability, while ink with 10 % FP content had the lowest viscosity and hardness, but it was not suitable for 3D printing. 3D printing of objects printed using Ink-C (5%FP and 0.8 %FGG) showed high support characteristic and attractive appearance. According to the international IDDSI testing standards, Ink-C (5%FP and 0.8 %FGG), Ink-E (15%FP and 0.8 %FGG), and Ink-F (20%FP and 0.8 %FGG) were defined as level 5-minced and moist foods.

3D printable vegan plant-based meat analogue: Fortification with three different mushrooms, investigation of printability, and characterization

In this study, a meat analogue formulation prepared using different protein sources as a printable ink for 3D printers and fortified with three different mushroom cultivars (reishi, Ganoderma lucidum (GL); saffron milk-cap, Lactarius deliciosus (LD); and oyster, Pleurotus ostreatus (PO)). 3D printing performance of the prepared inks was evaluated by factorial design in terms of nozzle height, printing speed, and flow compensation. New methods of maximum layer height and reprintability of plant-based meat analogues were conducted for the first time. Inks were characterized by analyzing rheological properties, microstructure, color characteristics, texture profile, cooking loss, amino acid content, and sensory evaluation. Results showed that the nozzle height and printing speed were found to be most effective on accuracy of prints and smoothness of layers. All inks (C, GL, LD and PO) represented shear-thinning and gel-like viscoelastic behavior (G' > G″) with predominant elasticity (tan δ < 1). Therefore they were suited for 3D printing and possessed supporting the following layers for additive manufacturing as well as meeting the criteria for a stable structure. Meat analogue was printed successfully without perceived defects in all formulations, except the GL was looking linty. LD and PO inks brought the advantage of recycling as a result of their re-printability whereas GL could not. Moreover, mushroom fortification reduced hardness, stiffness, springiness, and chewiness properties of the meat analogues whereas it increased the juiciness with reasonable overall acceptance. Mushroom fortification also enhanced the nutritional value and improved release of umami amino acids. The findings of the study demonstrated that mushrooms could be a functional and nutritious candidate for 3D printable plant-based meat analogues.

Structural, rheological, and gelling characteristics of starch-based materials in context to 3D food printing applications in precision nutrition

Starch-based materials have viscoelasticity, viscous film-forming, dough pseudoplasticity, and rheological properties, which possess the structural characteristics (crystal structure, double helix structure, and layered structure) suitable for three-dimensional (3D) food printing inks. 3D food printing technology has significant advantages in customizing personalized and precise nutrition, expanding the range of ingredients, designing unique food appearances, and simplifying the food supply chain. Precision nutrition aims to consider individual nutritional needs and individual differences, which include special food product design and personalized precise nutrition, thus expanding future food resources, then simplifying the food supply chain, and attracting extensive attention in food industry. Different types of starch-based materials with different structures and rheological properties meet different 3D food printing technology requirements. Starch-based materials suitable for 3D food printing technology can accurately deliver and release active substances or drugs. These active substances or drugs have certain regulatory effects on the gut microbiome and diabetes, so as to maintain personalized and accurate nutrition.

Image-based assessment and machine learning-enabled prediction of printability of polysaccharides-based food ink for 3D printing

Despite the growing demand and interest in 3D printing for food manufacturing, predicting printability of food-grade materials based on biopolymer composition and rheological properties is a significant challenge. This study developed two image-based printability assessment metrics: printed filaments' width and roughness and used these metrics to evaluate the printability of hydrogel-based food inks using response surface methodology (RSM) with regression analysis and machine learning. Rheological and compositional properties of food grade inks formulated using low-methoxyl pectin (LMP) and cellulose nanocrystals (CNC) with different ionic crosslinking densities were used as predictors of printability. RSM and linear regression showed good predictability of rheological properties based on formulation parameters but could not predict the printability metrics. For a machine learning based prediction model, the printability metrics were binarized with pre-specified thresholds and random forest classifiers were trained to predict the filament width and roughness labels, as well as the overall printability of the inks using formulation and rheological parameters. Without including formulation parameters, the models trained on rheological measurements alone were able to achieve high prediction accuracy: 82% for the width and roughness labels and 88% for the overall printability label, demonstrating the potential to predict printability of the polysaccharide inks developed in this study and to possibly generalize the models to food inks with different compositions.

Designing future foods: Harnessing 3D food printing technology to encapsulate bioactive compounds

Bioactive compounds (BCs) provide numerous health benefits by interacting with one or more components of living tissues and systems. However, despite their potential health benefits, most of the BCs have low bioaccessibility and bioavailability, hindering their potential health-promoting activities. The conventional encapsulation techniques are time-consuming and have major limitations in their food applications, including the use of non-food grade chemicals, undesired sensory attributes, and storage stability issues. A cutting-edge, new technique based on 3D printing can assist in resolving the problems associated with conventional encapsulation technologies. 3D food printing can help protect BCs by incorporating them precisely into three-dimensional matrices, which can provide (i) protection during storage, (ii) enhanced bioavailability, and (iii) effective delivery and controlled release of BCs. Recently, various 3D printing techniques and inks have been investigated in order to create delivery systems with different compositions and geometries, as well as diverse release patterns. This review emphasizes the advances in 3D printing-based encapsulation approaches, leading to enhanced delivery systems and customized food formulations.

Three-Dimensional Printing of Foods: A Critical Review of the Present State in Healthcare Applications, and Potential Risks and Benefits

Three-dimensional printing is one of the most precise manufacturing technologies with a wide variety of applications. Three-dimensional food printing offers potential benefits for food production in terms of modifying texture, personalized nutrition, and adaptation to specific consumers' needs, among others. It could enable innovative and complex foods to be presented attractively, create uniquely textured foods tailored to patients with dysphagia, and support sustainability by reducing waste, utilizing by-products, and incorporating eco-friendly ingredients. Notable applications to date include, but are not limited to, printing novel shapes and complex geometries from candy, chocolate, or pasta, and bio-printed meats. The main challenges of 3D printing include nutritional quality and manufacturing issues. Currently, little research has explored the impact of 3D food printing on nutrient density, bioaccessibility/bioavailability, and the impact of matrix integrity loss on diet quality. The technology also faces challenges such as consumer acceptability, food safety and regulatory concerns. Possible adverse health effects due to overconsumption or the ultra-processed nature of 3D printed foods are major potential pitfalls. This review describes the state-of-the-art of 3D food printing technology from a nutritional perspective, highlighting potential applications and current limitations of this technology, and discusses the potential nutritional risks and benefits of 3D food printing.

Revolutionizing goat milk gels: A central composite design approach for synthesizing ascorbic acid-functionalized iron oxide nanoparticles decorated alginate-chitosan nanoparticles fortified smart gels

Goat milk gels (GMGs) are popular food due to their high water content, low-calorie density, appealing taste, texture enhancers, stability, and satiety-enhancing characteristics, making them ideal for achieving food security and zero hunger. The GMGs were optimized using the central composite design matrix of response surface methodology using goat milk powder (35-55 g), whole milk powder (10-25 g), and potato powder (10-15 g) as independent variables. In contrast, complex modulus, flow stress, and forward extrudability were chosen as dependent variables. The maximum value of complex modulus 33670.9 N, good flow stress 7863.6 N, and good extrudability 65.32 N was achieved under optimal conditions. The optimized goat milk gel was fortified with ascorbic acid-coated iron oxide nanoparticle (magnetic nature) decorated alginate-chitosan nanoparticles (AA-MNP@CANPs), making it nutritionally rich in an economically feasible way-the decorated AA-MNP@CANPs characterized for size, shape, crystallinity, surface charge, and optical characteristics. Finally, the optimized fortified smart GMGs were further characterized via Scanning electron microscopy, Rheology, Texture profile analysis, Fourier transforms infrared (FTIR), and X-Ray Diffraction (XRD). The fortified smart GMGs carry more nutritional diversity, targeted iron delivery, and the fundamental sustainability development goal of food security.

Rheological property, β-carotene stability and 3D printing characteristic of whey protein isolate emulsion gels by adding different polysaccharides

Emulsion gels with unique structural and mechanical properties have promising applications in 3D food printing. The purpose of this paper was to investigate the rheological property, β-carotene stability and 3D printing characteristic of whey protein isolate (WPI) emulsion gels by adding guar gum (GG), locust bean gum (LBG), xanthan gum (XG) and gum arabic (GA). The results showed that all samples exhibited shear thinning behavior and elastic characteristic. XG could reduce water mobility and increase WHC of WPI emulsion gel. The disulfide bond was the main chemical molecular force of emulsion gels, and XG significantly increased the hydrophobic interactions. GG and LBG increased gel strength, hardness and gumminess, reduced springiness, cohesiveness and chewiness of emulsion gels. GG sample had the best printing performance, more uniform network structure and better stability of β-carotene. This study provided a theoretical basis for 3D printing functional food.

Microwave-Induced Rapid Shape Change of 4D Printed Vegetable-Based Food

Microwave heating acts as an environmental stimulus factor to induce rapid shape changes in 4D-printed stereoscopic models over time. The influence of microwave power and model structure on the shape change behavior was explored, and the applicability of the deformed method to other vegetable-based gels was verified. The results described that the G', G″, η, and proportion of bound water of yam gels increased with the increase in yam powder content, and the yam gel with 40% content had the best printing effect. The IR thermal maps showed the microwaves first gathered in the designed gully region caused the swelling phenomenon, which induced the printed sample to undergo a bird-inspired "spreading of wings" process within 30 s. Increasing the microwave power and microwave heating time were able to increase the bending angles and dehydration rates of the printed samples, thus improving the deformed degree and deformed speed. Different model base thicknesses (4, 6, 8, and 10 mm) also had significant effects on the shape change of the printed structures. The efficiency of the shape changes of 4D-printed structures under microwave induction can be judged by studying the dielectric properties of the materials. In addition, the deformed behaviors of other vegetable gels (pumpkin and spinach) verified the applicability of the 4D deformed method. This study aimed to create 4D-printed food with personalized and rapid shape change behavior, providing a basis for the application scenarios of 4D-printed food.

Physico-chemical and Textural Properties of 3D Printed Plant-based and Hybrid Soft Meat Analogs

This study investigated the physico-chemical and textural properties of 3D-printed pea protein-only and pea protein-chicken-based hybrid meat analogs. Both pea protein isolate (PPI)-only and hybrid cooked meat analogs had a similar moisture content of approximately 70%, which was similar to that of chicken mince. However, the protein content increased significantly with the amount of chicken in the hybrid paste undergoing 3D printing and cooking. Significant differences were observed in the hardness values of the non-printed cooked pastes and the 3D printed cooked counterparts, suggesting that the 3D printing process reduces the hardness of the samples and is a suitable method to produce a soft meal, and has significant potential in elderly health care. Scanning electron microscopy (SEM) revealed that adding chicken to the plant protein matrix led to better fiber formation. PPI itself was not able to form any fibers merely by 3D printing and cooking in boiling water. Protein-protein interactions were also studied through the protein solubility test, which indicated that hydrogen bonding was the major bonding that contributed to the structure formation in cooked printed meat analogs. In addition, disulfide bonding was correlated with improved fibrous structures, as observed through SEM.

Bigels constructed from hybrid gelator systems: bulk phase-interface stability and 3D printing

In this study, edible bigels with different ratios of beeswax-based oleogel to gellan gum-based hydrogel were developed and characterized. Gellan gum formed a 3D network in water through hydrogen bonding. Beeswax formed a crystalline network in the oil phase, which prevented the flow of oil and formed an oleogel. The position of the droplets is fixed by the crystallization of glycerol monostearate (GMS) at the interface. Bigels with different oleogel contents presented different types of O/W (oleogel content was less than 62%), semi-bicontinuous (oleogel content was 62-68%), and W/O bigels (oleogel content was more than 70%), respectively. Rheological experiments showed bigels had a shear thinning ability, which was suitable for extrusion 3D printing. Then the applicability of 3D printing was studied and it was found that the self-supporting ability of bigels became stronger with the increase of oleogel content. Functional pigments were incorporated into the bigel inks, making the 3D printing product nutrient-rich and color customizable. These results would favor guiding the preparation of bigels with adjusted physical properties and delicate structures for 3D food printing to satisfy the personal desire of consumers.

Recent trends of 3D printing based on starch-hydrocolloid in food, biomedicine and environment

People are exploring the potential application of 3D printing in food, biomedicine and environment, but it is urgent to find suitable bio-ink. Bio-ink compounded with starch and hydrocolloid can not only improve the rheology, structure and printability of starch-based edible bio-ink, but also endow it with other functional characteristics, so that it can be applied to food, biomedicine and even the environment, and meet the strategic needs of national health, green and sustainable development. In this paper, hydrocolloids are reviewed as potential means to regulate the physicochemical properties of starch, which endows it with good printability and presents excellent printing products. The specific applications of the bio-ink in the fields of food, biomedicine and environment in hypoglycemic, lipid-lowering, swallowable food, delivery, intelligent materials, and bio-sensor are also discussed. Then, the challenges and future development trends of realizing large-scale application are prospected. Proper physicochemical properties of starch-hydrocolloid are positively correlated with printability. The presentation of excellent printability has realized the application in different fields, not only satisfies most people, but also create benefits for some specific people. This review is expected to provide some theoretical guidance for the further development of 3D printing technology and its large-scale application.

Designing 3D printable food based on fruit and vegetable products-opportunities and challenges

3D printing is an innovative technology for food industry, which provides tremendous opportunities for the designing of customized and personalized nutrition for fruit and vegetable based food products. Various researchers have worked on the development of printable ink, stability of printed products and quality parameters. The aim of this review is to cover the most recent advancements on 3D food printing for fruits and vegetables and explore the prospect. Extrusion-based 3D printing is the most extensively used technique due to their several advantages. The review examines the three groups of extrusion printing such as room temperature extrusion, fused deposition manufacturing and gel forming extrusion. The development in last few years in the area of 3D food products of fruits and vegetables powder has been assembled in this review article. Based on these results, it can conclude that fruit and vegetable has been successfully used to fabricate 3D and even 4D food products. Future studies are required for improvement in pre and post-processing technique. Functional food can also be developed by using 3D printing but more research is required in this area.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05386-4.

Advances in the Potential Application of 3D Food Printing to Enhance Elderly Nutritional Dietary Intake

The contradiction between the growing demand from consumers for "nutrition & personalized" food and traditional industrialized food production has consistently been a problem in the elderly diet that researchers face and discuss. Three-dimensional (3D) food printing could potentially offer a solution to this problem. This article reviews the recent research on 3D food printing, mainly including the use of different sources of protein to improve the performance of food ink printing, high internal phase emulsion or oleogels as a fat replacement and nutrition delivery system, and functional active ingredients and the nutrition delivery system. In our opinion, 3D food printing is crucial for improving the appetite and dietary intake of the elderly. The critical obstacles of 3D-printed food for the elderly regarding energy supplements, nutrition balance, and even the customization of the recipe in a meal are discussed in this paper. By combining big data and artificial intelligence technology with 3D food printing, comprehensive, personalized, and customized geriatric foods, according to the individual traits of each elderly consumer, will be realized via food raw materials-appearance-processing methods. This article provides a theoretical basis and development direction for future 3D food printing for the elderly.

Impact of Apricot Pulp Concentration on Cylindrical Gel 3D Printing

The process of 3D food printing is a rapidly growing field that involves the use of specialized 3D printers to produce food items with complex shapes and textures. This technology allows the creation of customized, nutritionally balanced meals on demand. The objective of this study was to evaluate the effect of apricot pulp content on printability. Additionally, the degradation of bioactive compounds of gels before and after printing was evaluated to analyze the effect of the process. For this proposal, physicochemical properties, extrudability, rheology, image analysis, Texture Profile Analysis (TPA), and bioactive compounds content were evaluated. The rheological parameters lead to higher mechanical strength and, thus, a decrease in elastic behavior before and after 3D printing as the pulp content increases. An increase in strength was observed when the pulp content increased; thus, sample gels with 70% apricot pulp were more rigid and presented better buildability (were more stable in their dimensions). On the other hand, a significant (p < 0.05) degradation of total carotenoid content after printing was observed in all samples. From the results obtained, it can be said that the gel with 70% apricot pulp food ink was the best sample in terms of printability and stability.

Integrated design of micro-fibrous food with multi-materials fabricated by uniaxial 3D printing

Owing to the interest in sustainable foods, a new approach known as 3D food printing is being employed to make fibrous foods for meat and fish substitutes. In this study, we developed a filament structure with a multi-material ink comprising fish surimi-based ink (SI) and plant-based ink (PI), using single-nozzle printing and steaming. PI and an SI + PI mix collapsed after printing owing to their low shear modulus, although both PI and SI showed gel-like rheological behaviors. However, unlike the control, the objects printed with two and four columns per filament remained stable and fiberized after steaming. Each SI and PI sample gelatinized irreversibly at approximately 50 °C. The different rheological values of these inks after cooling resulted in relatively strong (PI) and weak (SI) fibers, which constructed a filament matrix. A cutting test demonstrated that the transverse strength of the fibrous structure of the printed objects was higher than the longitudinal strength, in contrast to that of the control. The degree of texturization increased with the fiber thickness based on the column number or nozzle size. Thus, we successfully designed a fibrous system using printing and post-processing and substantially broadened the application opportunities for creating fibril matrices for sustainable food analogs.

Modulating hydrophilic properties of β-cyclodextrin/carboxymethyl cellulose colloid particles to stabilize Pickering emulsions for food 3D printing

This research investigated edible Pickering emulsions stabilized by polysaccharide complexes as inks for food 3D printing. The interface membrane structure in the Pickering emulsion system was formed using complexes consisting of β-cyclodextrin (β-CD) and carboxymethyl cellulose (CMC). Except for provide sufficient steric barrier and electrostatic repulsion to increase the stability of the Pickering emulsions, the interface membrane constructs also can demonstrate good biphasic wettability and lower oil/water interfacial tension. The hydrophilicity of complexes (β-CD/CMC) was mainly adjusted by the ratio of β-CD/CMC (R_β/C) and the substitution degree (DS) of CMC, which further adjusted the physical and chemical properties of Pickering emulsion to make it correspond to the rheological behavior applied to 3D printing. The stable Pickering emulsion (R_β/C = 2:2, DS = 1.2, weight ratio of oil phase (φ) = 65 %) displayed excellent printing potential by characterizations analysis of Pickering emulsions. The smoothness, viscosity, and self-supporting ability of the Pickering emulsion under the optimized conditions were further analyzed using a filling density printing experiment of a cuboid model. The emulsifying properties of β-CD were adjusted by hydrophilic CMC to achieve the required amphipathic properties of the complexes to develop Pickering emulsions for food 3D printing.

3D Printing of Functional Strawberry Snacks: Food Design, Texture, Antioxidant Bioactive Compounds, and Microbial Stability

3D printing technology (3DP) as additive manufacturing is an innovative design technology that can meet the individual nutritional and sensory needs of consumers. Therefore, the aim of this work was to apply 3DP in the production of a strawberry-based functional product with the addition of two hydrocolloids (corn and wheat starch) in three proportions (10, 15 and 20%) and to investigate the influence of 3DP process parameters on physico-chemical and textural properties, as well as the bioactive and antioxidant potential and microbiological stability, with(out) the addition of natural antimicrobial agents. Starch type had a significant effect on all tested bioactive compounds, as well as on starch content, except for total phenolic and hydroxycinnamic acid contents. Considering the content of bioactive compounds and antioxidant capacity, program 2 proved to be more suitable than program 1. All samples exhibited good textural properties, a high degree of stability and minimal geometric deviations. Regarding microbiological safety, no pathogenic bacteria were found in the 3DP samples during storage. The 3DP sample with added citral at a concentration of 75 mg L^-1 showed the best microbiological quality. Ultimately, 3DP can be successfully used for the production of new strawberry-based functional products.

Textural characteristics and color analyses of 3D printed gluten-free pizza dough and crust

A new methodology was developed to print pizza dough with a gluten free flour blend or commercial gluten whole wheat flour using extrusion-based 3-D printing technology. Their physical properties were compared to commercially available pizza dough and crust. The optimized nozzle size, print speed, ingredient flow speed, and line thickness for the 3-D printing of pizza dough were: 0.04 cm, 800 cm/minutes, 1.8, and 0.34 cm, respectively. The printed gluten-free pizza dough required 120 min of fermentation to obtain a comparable color and textural profile (P < 0.05) to that of the gluten whole wheat flour dough fermented for 60 min. The 3-D printed gluten free, whole-wheat pizza and commercially available wheat flour dough and standard crusts demonstrated identical Δ E ab ∗ values of 0.14 and 0.13, respectively with brownness index (BI) values of 1.47 and 1.62, respectively. Textural profile analysis (TPA) of 3-D printed gluten free and whole wheat pizza dough, crust and the commercial standard wheat flour pizza dough and crust demonstrated significant (P < 0.05) correlations in terms of hardness, fracturability, adhesiveness, springiness, cohesiveness, chewiness, and resilience. An optimized method was developed to prepare gluten-free pizza dough and crust with similar functional properties to that of gluten whole wheat flour dough and crust.