Formulation engineering of food systems for 3D-printing applications - A review

Rheological insights into 3D printing of drug products: Drug nanocrystal-poloxamer gels for semisolid extrusion

The importance of ink rheology to the outcome of 3D printing is well recognized. However, rheological properties of printing inks containing drug nanocrystals have not been widely investigated. Therefore, the objective of this study was to establish a correlation between the composition of nanocrystal printing ink, the ink rheology, and the entire printing process. Indomethacin was used as a model poorly soluble drug to produce nanosuspensions with improved solubility properties through particle size reduction. The nanosuspensions were further developed into semisolid extrusion 3D printing inks with varying nanocrystal and poloxamer 407 concentrations. Nanocrystals were found to affect the rheological properties of the printing inks both by being less self-supporting and having higher yielding resistances. During printing, nozzle blockages occurred. Nevertheless, all inks were found to be printable. Finally, the rheological properties of the inks were successfully correlated with various printing and product properties. Overall, these experiments shed new light on the rheological properties of printing inks containing nanocrystals.

The Future of Food

The global food systems face significant challenges driven by population growth, climate change, geopolitical conflicts, crises, and evolving consumer preferences. Intending to address these challenges, optimizing food production, adopting sustainable practices, and developing technological advancements are essential while ensuring the safety and public acceptance of innovations. This review explores the complex aspects of the future of food, encompassing sustainable food production, food security, climate-resilient and digitalized food supply chain, alternative protein sources, food processing, and food technology, the impact of biotechnology, cultural diversity and culinary trends, consumer health and personalized nutrition, and food production within the circular bioeconomy. The article offers a holistic perspective on the evolving food industry characterized by innovation, adaptability, and a shared commitment to global food system resilience. Achieving sustainable, nutritious, and environmentally friendly food production in the future involves comprehensive changes in various aspects of the food supply chain, including innovative farming practices, evolving food processing technologies, and Industry 4.0 applications, as well as approaches that redefine how we consume food.

Effects of wheat protein on hot-extrusion 3D-printing performance and the release behaviours of caffeic acid-loaded wheat starch

In this study, the effects of wheat protein (WP) on the hot-extrusion 3D-printing (HE-3DP) performance of wheat starch (WS) gels, as well as effects of such gels on the encapsulation of caffeic acid, were investigated for the first time. The HE-3DP results show that the addition of WP can reduce print-line width and improve printing accuracy and fidelity, and the best printing results were achieved when using gels with 10 % WP. The rheological results show that WP reduced the gels' linear viscoelastic region (LVR), yield stress (τy), flow stress (τf) and consistency factor (K) but increased their structural recovery rate, which facilitated smooth extrusion during 3D printing and, thus, improved printing accuracy. The analysis of X-ray diffraction and small-angle X-ray scattering indicates that adding WP to WS could increase the mass fractal dimension and lead to denser gel network structures. The results regarding release kinetics demonstrate that the maximum release of caffeic acid from gels decreased by 28 % with the addition of WP, indicating slow-release behaviour. This study provided valuable information about processing wheat products via 3D printing.

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.

Modeling and Simulation of 3D Food Printing Systems-Scope, Advances, and Challenges

Food 3D printing is a computer-aided additive manufacturing technology that can transform foods into intricate customized forms. In the past decade, this field has phenomenally advanced and one pressing need is the development of strategies to support process optimization. Among different approaches, a range of modeling methods have been explored to simulate 3D printing processes. This review details the concepts of various modeling techniques considered for simulating 3D printing processes and their application range. Most modeling studies majorly focus on predicting the mechanical behavior of the material supply, modifying the internal texture of printed constructs, and assessing the post-printing stability. The approach can also be used to simulate the dynamics of 3D printing processes, in turn, assisting the design of 3D printers based on material composition, properties, and printing conditions. While most existing works are associated with extrusion-based 3D printing, this article presents scope for expanding avenues with prominent research and commercial interest. The article concludes with challenges and research needs, emphasizing opportunities for computational and data-driven dynamic simulation approaches for multi-faceted applications.

Role of Rheology in Morphology Development and Advanced Processing of Thermoplastic Polymer Materials: A Review

This review presents fundamental knowledge and recent advances pertaining to research on the role of rheology in polymer processing, highlights the knowledge gap between the function of rheology in various processing operations and the importance of rheology in the development, characterization, and assessment of the morphologies of polymeric materials, and offers ideas for enhancing the processabilities of polymeric materials in advanced processing operations. Rheology plays a crucial role in the morphological evolution of polymer blends and composites, influencing the type of morphology in the case of blends and the quality of dispersion in the cases of both blends and composites. The rheological characteristics of multiphase polymeric materials provide valuable information on the morphologies of these materials, thereby rendering rheology an important tool for morphological assessment. Although rheology extensively affects the processabilities of polymeric materials in all processing operations, this review focuses on the roles of rheology in film blowing, electrospinning, centrifugal jet spinning, and the three-dimensional printing of polymeric materials, which are advanced processing operations that have gained significant research interest. This review offers a comprehensive overview of the fundamentals of morphology development and the aforementioned processing techniques; moreover, it covers all vital aspects related to the tailoring of the rheological characteristics of polymeric materials for achieving superior morphologies and high processabilities of these materials in advanced processing operations. Thus, this article provides a direction for future advancements in polymer processing. Furthermore, the superiority of elongational flow over shear flow in enhancing the quality of dispersion in multiphase polymeric materials and the role of extensional rheology in the advanced processing operations of these materials, which have rarely been discussed in previous reviews, have been critically analyzed in this review. In summary, this article offers new insights into the use of rheology in material and product development during advanced polymer-processing operations.

Rheological and physicochemical properties of Spirulina platensis residues-based inks for extrusion 3D food printing

Novel food matrices (such as microalgae, plants, fungi, and microbial proteins) with high protein content and biological value, good amino acid profile, and functionality have been explored. Phycocyanin and active polysaccharides extracted from Spirulina platensis are used as food additives, treatment of colitis, as well as obesity prevention. However, most of the remaining Spirulina platensis residues are mainly used as fish feed at present. 3D food printing is one of the promising development techniques used in the food industry. The aim of this study was to develop a novel 3D printing material of Spirulina platensis residues with shear thinning characteristics, high viscosity and rapid recovery. The effects of moisture content and pretreatment method on the rheological properties of Spirulina platensis residues were clarified. Scanning electron microscopy was used to observe the microstructure and texture profile analysis was used to determine the texture characteristics of Spirulina platensis residues, rheology was used to determine the key 3D printing factors such as viscosity and modulus of Spirulina platensis residues. More importantly, the printing process could be realized under ambient conditions. The development of microalgae residue ink promoted the high-value and comprehensive utilization of microalgae, and also broadened the application of microalgae in the food field.

Effects of CaCl2 on 3D Printing Quality of Low-Salt Surimi Gel

In order to develop low-salt and healthy surimi products, we limited the amount of NaCl to 0.5 g/100 g in this work and studied the effect of CaCl₂ (0, 0.5, 1.0, 1.5, and 2.0 g/100 g) on the 3D printing quality of low-salt surimi gel. The results of rheology and the 3D printing showed that the surimi gel with 1.5 g/100 g of CaCl₂ added could squeeze smoothly from the nozzle and had good self-support and stability. The results of the chemical structure, chemical interaction, water distribution, and microstructure showed that adding 1.5 g/100 g of CaCl₂ could enhance the water-holding capacity and mechanical strength (the gel strength, hardness, springiness, etc.) by forming an orderly and uniform three-dimensional network structure, which limited the mobility of the water and promoted the formation of hydrogen bonds. In this study, we successfully replaced part of the salt in surimi with CaCl₂ and obtained a low-salt 3D product with good printing performance and sensory properties, which could provide theoretical support for the development of healthy and nutritious surimi products.

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.

Correlating process parameters and print accuracy of 3D-printable heat acid coagulated milk semisolids and polyol matrix: implications for testing methods

The primary additive manufacturing (AM) technique for all high-viscosity food composites is extrusion-based. Therefore, understanding the impact of process parameters involved is crucial in fulfilling the demand characteristics of the printed constructs. In this regard, a correlation between print accuracy and critical 3D printing (3DP) process variables as a strategy for expediting the selection of 3D printable food inks has the most potential for success. This paper studies the effectiveness of using heat-acid coagulated milk semisolids and polyol matrix as 3D printable food ink for high-quality prints. The study focused on the critical material properties and conducted rheological characterization and particle size distribution analysis. The study obtained the effective range of printing parameters for various process variables using a mathematical model that employed finite element analysis (FEA) to define the flow field characteristics. The dimensional accuracy of the printed constructs under different process variables was determined by utilizing image processing methods. A multi-objective optimization was carried out using the desirability function method to obtain the key correlations between the process parameters for the best-printed construct.

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.

Recent Advances in the Processing and Manufacturing of Plant-Based Meat

Plant protein technology is a core area of biotechnology to ease the problem of human protein demand. Plant-based meat based on plant protein technology is a growing concern by global consumers in alleviating environmental pollution, cutting down resources consumption, and improving animal welfare. Plant-based meat simulates the texture, taste, and appearance of animal meat by using protein, lipid, carbohydrate, and other plant nutrients as the main substances. This review summarizes the main components of plant-based meat, processing technology, standard formula, market competition, and formula and texture of future research directions. According to the existing methods of plant-based meat fiber forming, the development process and characteristics of four production processes and equipment of plant-based meat spinning, extrusion, shearing, and 3D printing are emphatically expounded. The processing principles and methods of different processing technologies in plant-based meat production are summarized. The production process and equipment of plant-based meat will pay more attention to the joint production of various processes to improve the defects of plant-based meat production process.

3D-Powder-Bed-Printed Pharmaceutical Drug Product Tablets for Use in Clinical Studies

Printing of phase 1 and 2a clinical trial formulations represents an interesting industrial application of powder bed printing. Formulations for clinical trials are challenging because they should enable flexible changes in the strength of the dosage form by varying the active pharmaceutical ingredient (API) percentage and tablet mass. The aim of this study was to investigate how powder bed 3D printing can be used for development of flexible platforms for clinical trials, suitable for both hydrophilic and hydrophobic APIs, using only conventional tableting excipients. A series of pre-formulation and formulation studies were performed to develop two platform formulations for clinical trials using acetaminophen and diclofenac sodium as model compounds and lactose and starch as excipients. The results showed that the type of starch used as the formulation binder must be optimized based on the type of API. Moreover, powder blend flow and liquid penetration ability proved to be critical material attributes (CMAs) that need to be controlled, particularly at high drug loading. Optimization of these CMAs was performed by selecting the appropriate particle size of the API or by addition of silica. A critical process parameter that had to be controlled for production of tablets of good quality was the quantity of the printing ink. After optimization of both the formulation and process parameters, two platform formulations, that is, one for each API, were successfully developed. Within each platform, drug loading from 5 up to 50% w/w and tablet mass from 50 to 500 mg were achieved. All 3D-printed tablets could be produced at tensile strength above 0.2 MPa, and most tablets could enable immediate release (i.e., >80% w/w within 30 min).

A Comprehensive Study on the Applications of Clays into Advanced Technologies, with a Particular Attention on Biomedicine and Environmental Remediation

In recent years, a great interest has arisen around the integration of naturally occurring clays into a plethora of advanced technological applications, quite far from the typical fabrication of traditional ceramics. This “second (technological) life” of clays into fields of emerging interest is mainly due to clays’ peculiar properties, in particular their ability to exchange (capture) ions, their layered structure, surface area and reactivity, and their biocompatibility. Since the maximization of clay performances/exploitations passes through the comprehension of the mechanisms involved, this review aims at providing a useful text that analyzes the main goals reached by clays in different fields coupled with the analysis of the structure-property correlations. After providing an introduction mainly focused on the economic analysis of clays global trading, clays are classified basing on their structural/chemical composition. The main relevant physicochemical properties are discussed (particular attention has been dedicated to the influence of interlayer composition on clay properties). Lastly, a deep analysis of the main relevant nonconventional applications of clays is presented. Several case studies describing the use of clays in biomedicine, environmental remediation, membrane technology, additive manufacturing, and sol-gel processes are presented, and results critically discussed.