Structural and Textural Characteristics of 3D-Printed Protein- and Dietary Fibre-Rich Snacks Made of Milk Powder and Wholegrain Rye Flour

Optimization of 3D Extrusion Printing Parameters for Raw and Extruded Dehulled Andean Fava Bean Flours Using Response Surface Methodology (RSM)

This study optimizes the 3D extrusion printing parameters-water-to-flour ratio (X1), temperature (X2), and printing speed (X3)-for raw (RFB) and extruded (EFB) dehulled Andean fava bean flours to maximize print quality and minimize structural defects. A 23 central composite design combined with response surface methodology (RSM) was used to identify the optimal conditions for achieving geometric precision, surface homogeneity, and textural stability. Physicochemical analyses showed that extrusion cooking substantially modified the composition and rheology of the flour. Compared with RFB, EFB exhibited lower protein and fiber contents, a higher proportion of digestible carbohydrates, and reduced rheological parameters (τ0, K, G', G″), which facilitated printing. The evaluation of different parameter combinations revealed notable differences between the two flours, with X1 and X2 exerting the greatest influence on print quality. For RFB, the highest desirability (0.853) was achieved at X1 = 0.806, X2 = 23.18 °C, and X3 = 2470.5 mm/min, yielding more uniform and firmer printed structures. In contrast, EFB reached a desirability of 0.844 at X1 = 1.66 °C, X2 = 56.82 °C, and X3 = 1505.43 mm/min, indicating its outstanding geometric accuracy and robustness. In conclusion, raw flour requires higher hydration and lower temperatures to prevent excessive viscosity. In contrast, extruded flour benefits from low water and high temperatures to achieve stable structures and firm textures. These findings demonstrate the feasibility of using Andean fava bean flour in 3D food printing to create nutrient-dense, functional foods with improved printability. This work offers practical applications for developing personalized foods-such as customized meals for individuals with specific dietary requirements-while contributing to sustainable and secure food production. Future research should address long-term storage, post-printing drying methods, and scaling production.

Development of special nutritional balanced food 3D printing products based on the mixing of animals/plants materials: research progress, applications, and trends

Food 3D printing brings food processing technology into the digital age. This is a vast field that can provide entertainment experience, personalized food and specific nutritional needs. However, the limited availability of suitable food raw materials has restricted the extensive use of 3D food printing processing technique. The search for novel nutritious and healthy food materials that meet the demand for 3D food printing processing technology is core of the sustainable development of this emerging technology. The printing mechanism, precise nutrition, future outlooks and challenges of 3D food printing technology application in hybrid plant and animal food materials are also analyzed.The results demonstrate that selecting suitable animal and plant materials and mixing them into 3D food printing ingredients without adding food additives can result in printable inks, which can also improve the nutritive value and eating quality of 3D food printed products. Sustainability of novel food materials such as animal cell culture meat and microbial protein mixed with conventional food materials to realize 3D printed food can be a potential research direction. Some other issues should also be considered in future research, such as evaluation of the nutritional efficacy of the product, product stability, shelf life, production efficiency and convenience of process operation.

Insights into the material and 3D printing behaviour of fiber-enriched protein gels

One of the widely used materials in food printing is soy protein isolate (SPI) due to its functional and nutritional properties. However, a major printing drawback of SPI gels is network brittleness due to extensive aggregation leading to rheological properties that are unsuitable for printing. In this study, 0.4 %, 0.8 %, 1.2 %, 1.6 % and 2.0 % w/w milled psyllium husk and apple fibers were integrated into 20 % w/w SPI inks to improve the network properties and printability. Microstructural, textural, rheological properties and printability were investigated by microscopy, texture profile analysis, rheometry and image analysis. Incorporating psyllium husk fibers resulted in an interpenetrating protein-fiber network. This led to an increase in the network strength from 2155.8 Pa to 4228.15 Pa, relative to soy protein inks only, making them less susceptible to deformation during extrusion. Additionally, the geometrical deviation of the printed cubes decreased from 37.00 ± 4.55 % (length) and 24.00 ± 4.45 % (height) in the control inks to 13.86 ± 1.61 % and 24.86 ± 3.17 % respectively at psyllium husk concentration of 2.0 w/w %. The results showed that psyllium husk improved ink flexibility due to the high water-holding capacity of the fibers while maintaining structural integrity. This study revealed that the interpenetrating network effect of soluble dietary fibers in SPI inks improved printability while apple fibers with a high fraction of insoluble fibers embedded in a soy protein ink network caused printing defects. The findings highlight the potential to understand the influence of dietary fiber with varying physicochemical properties on 3D food printing of protein inks.

Additive manufacturing technology in the development of easy to swallow and digest foods for the elderly

The ageing of the population is a major challenge for the world. The elderly face a number of functional deteriorations in the body during the ageing process. Among these, swallowing and digestion are the two biggest challenges that elderly individuals face. The individualized, customized, and digitized approach to food processing offered using additive manufacturing technology also referred to as 3D printing technology-makes it particularly well-suited to the production of foods that are easy to swallow and digest for the elderly. The application of 3D food printing technology for producing foods that are easy to swallow and digest for the elderly is examined in this article. Meanwhile, it is discussed using some texture-improving techniques for making foods that are easier for the elderly to swallow. Additionally, the challenges and solutions associated with 3D food printing in the manufacturing of foods for the elderly are explored. Overall, this review offers some insights from material classification for the use of 3D food printing technology in the production of foods that are easy to swallow and digestible food for the elderly.

Effect of 3D printing and traditional molding on phenolic compounds and antioxidant activity in steamed bread

The production process of fermented black wheat steamed bread is closely related to the overall quality and nutritional content. In this study, we investigated the accuracy, product texture profile and antioxidant activity of fermented black wheat steamed bread samples produced by piston and spiral three-dimensional (3D) printers. The steaming process generally increased the total phenolic content and flavonoid content of the samples. The spiral 3D printer obtained samples with higher accuracy, total phenolic content up to 1960.43 Mg GAE/kg, and higher cellular antioxidant activity (CAA) content. The samples printed by the piston 3D printer showed higher total flavonoid content (575.75 Mg QE/kg), 2, 2'-azobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) values and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) values. This study shows that antioxidant-rich health foods can be prepared using 3D printed black wheat flour. The choice of 3D printing method affects the overall quality and nutritional content of the final product.

Protein and protein-polysaccharide composites-based 3D printing: The properties, roles and opportunities in future functional foods

The food industry is undergoing a significant transformation with the advancement of 3D technology. Researchers in the field are increasingly interested in using protein and protein-polysaccharide composite materials for 3D printing applications. However, maintaining nutritional and sensory properties while guaranteeing printability of these materials is challenging. This review examines the commonly used protein and composite materials in food 3D printing and their roles in printing inks. This review also outlines the essential properties required for 3D printing, including extrudability, appropriate viscoelasticity, thixotropic properties, and gelation properties. Furthermore, it explores the wide range of potential applications for 3D printing technology in novel functional foods such as space food, dysphagia food, kid's food, meat analogue, and other specialized food products.

3-D printed meat alternatives based on pea and single cell proteins and hydrocolloids: Effect of paste formulation on process-induced fibre alignment and structural and textural properties

Extrusion-based 3D food printing can be used as an alternative structuring technique to traditional extrusion processing for creating meat-like structures. This study focused on 3-D food printing to generate structures analogous to meat by using various combinations of texturized pea protein fibrils, microbial Single Cell Protein (SCP) and hydrocolloids locust bean gum and/or sodium alginate. Simple moulding was utilized as benchmarking to better understand the 3D printing-induced structural effects. To gain understanding of the interactions between proteins of different origin (plant and SCP) and with hydrocolloids, structural, textural and rheological properties were analysed. Oscillatory stress sweeps of all printing pastes revealed elastic-dominant rheological behaviour (G' 4000-6000 Pa) with a defined yield stress (25-60 Pa) explaining their printability and shape stability. X-ray microtomography of ion-crosslinked analogues showed a printing-induced preferential alignment of fibrils in the direction of nozzle movement, while moulding led to a random orientation. Textural characterization via bi-directional cutting tests demonstrated higher cutting force in transversal (FT) over longitudinal (FL) direction in 3D-printed samples and equal forces in moulded samples. The anisotropy index (AI = FT/FL) of printed samples ranged between 1.4 and 2.5, indicating anisotropic texture, and 0.8-1 for moulded samples indicating isotropic texture. This study demonstrated the applicability of paste-extrusion in generating anisotropic structures analogous to meat by process-induced fibril alignment. The results support further development of 3D food printing technology in design of sustainable meat alternatives resembling whole-muscle meat.

Enhanced Elderberry Snack Bars: A Sensory, Nutritional, and Rheological Evaluation

Interest in functional foods is continuously increasing, having the potential to be an ally in reducing cardiometabolic risk factors. This study focuses on developing and evaluating oat- and millet-based snack bars enriched with freeze-dried elderberry powder (FDEBP), aiming to combine great taste with enhanced nutritional value, antioxidant properties, and prebiotic potential. The research encompassed a sensory evaluation, nutritional assessment, and rheological analysis of the snack bars. A hedonic test was conducted to gauge consumer preferences and overall liking, providing insights into taste, texture, and acceptance. Sensory evaluation revealed positive feedback from participants, and acceptance rating scores ranged from 7 to 8.04, the best score recorded by one of the enhanced bars with 1% FDEBP. The rheological analysis determined the bars' dynamic storage modulus (G') and loss modulus (G″), assessing the material's elasticity and mechanical properties. Results showed that the incorporation of 0.5% and 1% FDEBP in the oat and millet snack bars significantly impacted their rheological properties, enhancing structural strength. Nutritional analysis demonstrated that the snack bars provided a complete mix of macronutrients required in a daily diet. The study sheds light on the potential of functional snack bars enriched with FDEBP, offering a delectable way to access essential nutrients and bioactive compounds in a minimally processed form, without the addition of sweeteners or additives, friendly to the gut microbiota.

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.

Nordic Crops as Alternatives to Soy-An Overview of Nutritional, Sensory, and Functional Properties

Soy (Glycine max) is used in a wide range of products and plays a major role in replacing animal-based products. Since the cultivation of soy is limited by cold climates, this review assessed the nutritional, sensory, and functional properties of three alternative cold-tolerant crops (faba bean (Vicia faba), yellow pea (Pisum sativum), and oat (Avena sativa)). Lower protein quality compared with soy and the presence of anti-nutrients are nutritional problems with all three crops, but different methods to adjust for these problems are available. Off-flavors in all pulses, including soy, and in cereals impair the sensory properties of the resulting food products, and few mitigation methods are successful. The functional properties of faba bean, pea, and oat are comparable to those of soy, which makes them usable for 3D printing, gelation, emulsification, and extrusion. Enzymatic treatment, fermentation, and fibrillation can be applied to improve the nutritional value, sensory attributes, and functional properties of all the three crops assessed, making them suitable for replacing soy in a broad range of products, although more research is needed on all attributes.

Application of Three-Dimensional Digital Photogrammetry to Quantify the Surface Roughness of Milk Powder

The surface appearance of milk powders is a crucial quality property since the roughness of the milk powder determines its functional properties, and especially the purchaser perception of the milk powder. Unfortunately, powder produced from similar spray dryers, or even the same dryer but in different seasons, produces powder with a wide variety of surface roughness. To date, professional panelists are used to quantify this subtle visual metric, which is time-consuming and subjective. Consequently, developing a fast, robust, and repeatable surface appearance classification method is essential. This study proposes a three-dimensional digital photogrammetry technique for quantifying the surface roughness of milk powders. A contour slice analysis and frequency analysis of the deviations were performed on the three-dimensional models to classify the surface roughness of milk powder samples. The result shows that the contours for smooth-surface samples are more circular than those for rough-surface samples, and the smooth-surface samples had a low standard deviation; thus, milk powder samples with the smoother surface have lower Q (the energy of the signal) values. Lastly, the performance of the nonlinear support vector machine (SVM) model demonstrated that the technique proposed in this study is a practicable alternative technique for classifying the surface roughness of milk powders.

Easy-to-swallow mooncake using 3D printing: Effect of oil and hydrocolloid addition

3D printing is a promising technology for food production, capable of producing and developing personalized food products. In recent years, research on the application of 3D printing technology to create easy-to-swallow foods for the elderly with dysphagia has received extensive attention. In this study, we applied dual nozzle 3D printing technology to develop an easy-to-swallow mooncake food using a traditional Chinese food, mooncake, as a model system. We optimized the printing dough ink formulation by setting up soybean oil gradient experiments and Arabic gum gradient experiments, and then we applied the optimized dough ink as the crust of the mooncake to produce easy-to-swallow mooncakes. The experimental results show that the addition of 2.5 g of soybean oil and 0.125 g of Arabic gum could improve the texture of the dough product and reduce its hardness and adhesiveness. The mooncake produced with this crust dough ink was rated in the IDDSI texture level four, which met expectations. Therefore, this work provides insights into the development of easy-to-swallow food products.

Texture modulation of starch-based closed-cell foams using 3D printing: Deformation behavior beyond the elastic regime

3-dimensional printing is a novel processing method used for the design and manipulation of food textures. The systematic characterization and modulation of 3D printed food textures is imperative for the future design of sensory profiles using additive manufacturing. For 3D printed closed-cell food foams, the clarification of the deformation behavior in relation to design parameters is of interest for the processing of customized food textures. For this reason, we studied the deformation behavior of 3D printed and thermally stabilized closed-cell starch-based foams beyond the elastic regime. Periodic spherical bubble configurations at different porosity levels were used to modulate the deformation behavior of the printed foams. From a processing perspective, the integration of in-line thermal stabilization was used to eliminate post-processing and to control the moisture content of the starch-based system. Compression analysis combined with FEM simulations were performed to characterize the strain rate dependency of textural properties, the stress relaxation, and the foam's stress-strain behavior with respect to the design porosity and bubble distribution. Results showed that the stress relaxation is solely dependent on cell wall properties while different stress-strain regimes showed distinct dependencies on design parameters such as bubble size and distribution. Consequently, the precise control of the large deformation behavior of foods using 3D printing is challenging due to the superposition of structural and geometrical dependencies. Finally, through the presented approach, the structure-deformation relations of 3D printed closed-cell food structures are adequately described.

Impact of internal structural design on quality and nutritional properties of 3D printed food products during post-printing: a critical review

3D food printing (3DFP) provides an excellent opportunity to deposit layers of multiple food materials to create unique complex structures of products with more engaging visuals, specific textures, and customized nutritional properties. Many printed products require post-printing processing which can result in sensory variance, texture changes, and even nutritional modification. Hence it is necessary to implement the design of the complex internal structure to ensure the desired quality of the printed products following post-printing. 3-D printing of various types of food products, for example, chocolate, cheese, meat, vegetables, fruits, fish, eggs, cereal-based products, and so on, has been examined with regard to post-printing requirements. This review aims to summarize the current work on the latest developments in 3DFP technology concerning the internal structure design of 3D printed products and its effect on quality during post-printing. The quality parameters include: textural, physical, morphological, and dimensional characteristics as well as nutritional properties. Furthermore, post-printing modifications such as 4D are also analyzed.

Bioprocessing of Wheat and Amaranth Bran for the Reduction of Fructan Levels and Application in 3D-Printed Snacks

Bran can enrich snacks with dietary fibre but contains fructans that trigger symptoms in people with irritable bowel syndrome (IBS). This study aimed to investigate the bioprocessing of wheat and amaranth bran for degrading fructans and its application (at 20% flour-based) in 3D-printed snacks. Bran was bioprocessed with Saccharomyces cerevisiae alone or combined with inulinase, Kluyveromyces marxianus, Limosilactobacillus fermentum, or commercial starter LV1 for 24 h. Fructans, fructose, glucose, and mannitol in the bran were analysed enzymatically. Dough rheology, snack printing precision, shrinkage in baking, texture, colour, and sensory attributes were determined. The fructan content of wheat bran was 2.64% dry weight, and in amaranth bran, it was 0.96% dry weight. Bioprocessing reduced fructan content (up to 93%) depending on the bran type and bioprocessing agent, while fructose and mannitol remained below the cut-off value for IBS patients. Bran bioprocessing increased the complex viscosity and yield stress of dough (by up to 43 and 183%, respectively) in addition to printing precision (by up to 13%), while it lessened shrinkage in baking (by 20-69%) and the hardness of the snacks (by 20%). The intensity of snack sensory attributes depended on the bran type and bioprocessing agent, but the liking ("neither like nor dislike") was similar between samples. In conclusion, snacks can be enriched with fibre while remaining low in fructans by applying bioprocessed wheat or amaranth bran and 3D printing.

Assessing and Quantifying the Surface Texture of Milk Powder Using Image Processing

Milk powders produced from similar spray dryers have different visual appearances, while the surface appearance of the powder is a key quality attribute because the smoothness of the milk powder also affects flowability and handling properties. Traditionally quantifying this nuanced visual metric was undertaken using sensory panelists, which is both subjective and time consuming. Therefore, it is advantageous to develop an on-line quick and robust appearance assessment tool. The aim of this work is to develop a classification model which can classify the milk powder samples into different surface smoothness groups. This work proposes a strategy for quantifying the relative roughness of commercial milk powder from 3D images. Photogrammetry equipment together with the software RealityCapture were used to build 3D models of milk powder samples, and a surface normal analysis which compares the area of the triangle formed by the 3 adjacent surface normals or compares the angle between the adjacent surface normals was used to quantify the surface smoothness of the milk powder samples. It was found that the area of the triangle of the smooth-surface milk powder cone is smaller than the area of the triangle of the rough-surface milk powder cone, and the angle between the adjacent surface normals of the rough-surface milk powder cone is larger than the angle between the adjacent surface normals of the smooth-surface milk powder cone, which proved that the proposed area metrics and angle metrics can be used as tools to quantify the smoothness of milk powder samples. Finally, the result of the support vector machine (SVM) classifier proved that image processing can be used as a preliminary tool for classifying milk powder into different surface texture groups.

Towards the creation of personalized bakery products using 3D food printing

Bakery products with interesting color, shape and texture have been created using 3D food printing. Current research focuses on the development of new formulations and the optimization of the printing and post-printing treatment processes, in order to obtain high-quality 3D-printed bakery products. Knowledge about food rheology is useful for the development of dough formulations with good 3D-printability. Additives such as hydrocolloids could improve the printability of dough, and novel ingredients are introduced via 3D printing to produce functional bakery products with potential health benefits. One of the main future promises of 3D printing lies in its ability to produce bakery products that are personalized in terms of sensorial properties and nutritional composition, in order to meet the preferences and dietary requirements of individual consumers. This chapter addresses the most recent developments in 3D-printed bakery foods and highlights some important research topics to further advance this field.

Faba Bean Fractions for 3D Printing of Protein-, Starch- and Fibre-Rich Foods

Food 3D printing allows for the production of personalised foods in terms of shape and nutrition. In this study, we examined whether protein-, starch- and fibre-rich fractions extracted from faba beans can be combined to produce fibre- and protein-rich printable food inks for extrusion-based 3D printing. Small amplitude oscillatory shear measurements were used to characterise the inks while compression tests and scanning electron microscopy were used to characterise the freeze-dried samples. We found that rheological parameters such as storage modulus, loss tangent and yield stress were related to ink printability and shape stability. Investigations on the effect of ink composition, infill pattern (honeycomb/grid) and direction of compression on textural and microstructural properties of freeze-dried 3D-printed objects revealed no clear effect of infill pattern, but a strong effect of direction of compression. Microstructure heterogeneity seemed to be correlated with the textural properties of the printed objects.

Rye Flour and Rye Bran: New Perspectives for Use

Rye (Secale cereale L.) is abundantly cultivated in countries like Europe and North America, particularly in regions where soil and climate conditions are unfavorable for the growth of other cereals. Among all the cereals generally consumed by human beings, rye grains are characterized by the presence of the highest content of fiber. They are also a rich source of many phytochemical compounds, which are mainly distributed in the outer parts of the grain. This review focuses on the current knowledge regarding the characteristics of rye bran and wholemeal rye flour, as well as their applications in the production of both food and nonfood products. Previous studies have shown that the physicochemical properties of ground rye products are determined by the type of milling technique used to grind the grains. In addition, the essential biologically active compounds found in rye grains were isolated and characterized. Subsequently, the possibility of incorporating wholemeal rye flour, rye bran, and other compounds extracted from rye bran into different industrial products is discussed.

Rye: Current state and future trends in research and applications

After wheat, rye is the second most important raw material for bread and bakery products, and it is one of the most excellent sources of dietary fibres and bioactive compounds. Besides, rye is utilised in more and more other food products as well, such as breakfast cereals, porridges, pasta, snack products, etc. Interestingly, its production is decreasing worldwide, probably because of the expansion of other cereals (e.g. triticale), but also the effect of climate change can also play a role therein. However, there is no doubt that scientific research aimed at studying the possible health benefits and the potential of rye in the development of novel food products has intensified over the past decade.

The aim of our paper is to make a comprehensive review of the latest results on the compositional and technological properties of rye that fundamentally influence its utilisation for food purposes. Furthermore, this review aims to identify the current development directions and trends of rye products.

Influence of Flour and Fat Type on Dough Rheology and Technological Characteristics of 3D-Printed Cookies

In this study, we designed high fiber cookie recipe without using additives by means of extrusion-based 3D printing. We aimed to relate printing quality and cookie physical properties with dough rheology and dietary fiber content depending on the flour (oat, rye, rice, and carob flour) and fat type (olive oil or butter). The flour choice influenced all cookie quality parameters: baking loss, color, line height and width, and dietary fiber content. Results indicated that lower baking loss and better printing quality were obtained for cookie dough containing olive oil, which had higher viscosity and consistency coefficient compared with dough containing butter. Cookies with olive oil in which part of the oat flour was replaced with rye and carob flour were printed with high accuracy (≥98%), close to the ideal 3D shape. Overall, this study demonstrates the importance of selecting fat and particularly flour, as well as the extrusion rate on the quality and repeatability of 3D-printed cookies.

Techno-Economic Prospects and Desirability of 3D Food Printing: Perspectives of Industrial Experts, Researchers and Consumers

3D food printing is an emerging food technology innovation that enables the personalization and on-demand production of edible products. While its academic and industrial relevance has increased over the past decade, the functional value of the technology remains largely unrealized on a commercial scale. This study aimed at updating the business outlook of 3D food printing so as to help entrepreneurs and researchers in the field to channel their research and development (R&D) activities. A three-phase mixed methods approach was utilized to gain perspectives of industrial experts, researchers, and potential consumers. Data were collected from two sets of interviews with experts, a survey with experts, and consumer focus group discussions. The results gave insights into key attributes and use cases for a 3D food printer system, including the techno-economic feasibility and consumer desirability of identified use cases. A business modelling workshop was then organized to translate these results into three refined value propositions for 3D food printing. Both the experts and consumers found personalized nutrition and convenience to be the most desirable aspects of 3D food printing. Accordingly, business models related to 3D printed snacks/meals in semi-public spaces such as fitness centers and hospitals were found to offer the highest business potential. While the technology might be mature enough at component level, the successful realization of such high-reward models however would require risk-taking during the developmental phase.