4D printing of products based on soy protein isolate via microwave heating for flavor development

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.

Evaluating the 3D printability of pearl millet flour with banana pulp blends

BACKGROUND

Three-dimensional (3D) food printing is a promising method for developing nutritious snack foods with complex and customized structures. In this study, to develop a pearl millet-based snack formulation, the printability of pearl millet flour (PMF) was assessed, without and with the addition of banana pulp (BP), a natural taste and flavor enhancer, at five different levels (PMF:BP of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100).

RESULTS

The water activity significantly decreased with increases in the proportion of BP; higher water activity was exhibited at 100:0 (0.99). The BP proportion influences all the color values (redness: 2-11; yellowness: 17-31.87; total color difference: 2-17). All formulations exhibited shear-thinning behavior (n = 0.02-0.49) and higher hardness (0.2-0.4 N), but not all were printable. A significant decrease in adhesiveness (-0.2 to -0.03 N s) and higher storage modulus (2000-6000 Pa) occurred with an increased proportion of BP. Findings from detailed rheological behavior assessment (static, dynamic and three-interval thixotropy tests) better correlated with trends observed during 3D extrusion printing. The highest yield stress was attained (80 Pa) in the 100:0 formulation. From the thixotropy test, more deformation (>80%) and recovery (>100%) were attained by three of the formulations (100:0, 80:20, 60:40). Overall, the best constructs were obtained (based on the visual sensory characteristics) for the 60:40 formulation printed at 600 mm min-1 printing speed and 240 rpm extrusion motor speed through a 1.22 mm nozzle.

CONCLUSION

The findings of this work will provide valuable insights into the development of novel millet-based 3D printed foods. © 2024 Society of Chemical Industry.

Recent advances on enhancing 3D printing quality of protein-based inks: A review

3D printing is an additive manufacturing technology that locates constructed models with computer-controlled printing equipment. To achieve high-quality printing, the requirements on rheological properties of raw materials are extremely restrictive. Given the special structure and high modifiability under external physicochemical factors, the rheological properties of proteins can be easily adjusted to suitable properties for 3D printing. Although protein has great potential as a printing material, there are many challenges in the actual printing process. This review summarizes the technical considerations for protein-based ink 3D printing. The physicochemical factors used to enhance the printing adaptability of protein inks are discussed. The post-processing methods for improving the quality of 3D structures are described, and the application and problems of fourth dimension (4D) printing are illustrated. The prospects of 3D printing in protein manufacturing are presented to support its application in food and cultured meat. The native structure and physicochemical factors of proteins are closely related to their rheological properties, which directly link with their adaptability for 3D printing. Printing parameters include extrusion pressure, printing speed, printing temperature, nozzle diameter, filling mode, and density, which significantly affect the precision and stability of the 3D structure. Post-processing can improve the stability and quality of 3D structures. 4D design can enrich the sensory quality of the structure. 3D-printed protein products can meet consumer needs for nutritional or cultured meat alternatives.

Effect of ferulic acid incorporation on structural, rheological, and digestive properties of hot-extrusion 3D-printed rice starch

The influence of ferulic acid (FA) on rice starch was investigated by incorporating it at various concentrations (0, 2.5, 5, 7.5, and 10 %, w/w, on dry starch basis) and subjecting the resulting composites to hot-extrusion 3D printing (HE-3DP) process. This study examined the effects of FA addition and HE-3DP on the structural, rheological, and physicochemical properties as well as the printability and digestibility of rice starch. The results indicated that adding 0-5 % FA had no significant effect; however, as the amount of FA increased, the printed product edges became less defined, the product's overall stability decreased, and it collapsed. The addition of FA reduced the elasticity and viscosity, making it easier to extrude the composite gel from the nozzle. Moreover, the crystallinity and short-range ordered structure of the HE-3D printed rice starch gel decreased with the addition of FA, resulting in a decrease in the yield stress and an increase in fluidity. Furthermore, the addition of FA reduced the digestibility of the HE-3D-printed rice starch. The findings of this study may be useful for the development of healthier modified starch products by adding bioactive substances and employing the 3D printing technology.

3D/4D printed super reconstructed foods: Characteristics, research progress, and prospects

Super reconstructed foods (SRFs) have characteristics beyond those of real system in terms of nutrition, texture, appearance, and other properties. As 3D/4D food printing technology continues to be improved in recent years, this layered manufacturing/additive manufacturing preparation technology based on food reconstruction has made it possible to continuously develop large-scale manufacture of SRFs. Compared with the traditional reconstructed foods, SRFs prepared using 3D/4D printing technologies are discussed comprehensively in this review. To meet the requirements of customers in terms of nutrition or other characteristics, multi-processing technologies are being combined with 3D/4D printing. Aspects of printing inks, product quality parameters, and recent progress in SRFs based on 3D/4D printing are assessed systematically and discussed critically. The potential for 3D/4D printed SRFs and the need for further research and developments in this area are presented and discussed critically. In addition to the natural materials which were initially suitable for 3D/4D printing, other derivative components have already been applied, which include hydrogels, polysaccharide-based materials, protein-based materials, and smart materials with distinctive characteristics. SRFs based on 3D/4D printing can retain the characteristics of deconstruction and reconstruction while also exhibiting quality parameters beyond those of the original material systems, such as variable rheological properties, on-demand texture, essential printability, improved microstructure, improved nutrition, and more appealing appearance. SRFs with 3D/4D printing are already widely used in foods such as simulated foods, staple foods, fermented foods, foods for people with special dietary needs, and foods made from food processingbyproducts.

Characterization of fruit pulp-soy protein isolate (SPI) complexes: Effect of superfine grinding

Superfine grinding (SG), as an innovative technology, was conducted to improve the physicochemical and structural properties of fruit pulps. Nectarine, apple, and honey peach were selected as the materials. With the increase in SG frequency, the soluble solids content, viscosity, D[4, 3], D[3, 2], G' and G″ of fruit pulps were evidently decreased, whereas the turbidity was increased. The smallest D[4, 3] (294.90 µm) and D[3, 2] (159.67 µm) were observed in nectarine pulp under SG at 50 Hz. The highest turbidity (266.33) was shown in honey peach pulp under SG at 50 Hz. The active groups of the fruit pulps with SG were exposed by Fourier transform infrared spectroscopy (FT-IR). Notably, the excessive destruction in structure was confirmed in SG with 50 Hz. With soy protein isolate (SPI) addition, D[4, 3] and D[3, 2] of complexes decreased, whereas G' and G″ increased. The formation of new fruit pulp-SPI complexes was demonstrated by FT-IR and LF-NMR analysis. The dense and uniform structure was found in complexes prepared by SPI and fruit pulp with 30 Hz SG. Especially, apple-SPI complex with 30 Hz SG showed the highest water-holding capacity (WHC) (0.75) and adhesiveness (7973.00 g s). A significant correlation between fruit pulps and the complexes was revealed. Taken together, the impact of SG modification on fruit pulps would enhance WHC, rheology, and textural properties of the fruit pulp-SPI complexes, especially for SG with 30 Hz. PRACTICAL APPLICATION: This research provided a comprehensive exploration of the potential of SG technology to modify fruit pulps, solving the diversity of textural customization problems and offering valuable insights for the development of semisolid food products.

Challenges and Prospects of Plant-Protein-Based 3D Printing

Three-dimensional (3D) printing is a rapidly developing additive manufacturing technique consisting of the deposition of materials layer-by-layer to produce physical 3D structures. The technique offers unique opportunities to design and produce new products that cater to consumer experience and nutritional requirements. In the past two decades, a wide range of materials, especially plant-protein-based materials, have been documented for the development of personalized food owing to their nutritional and environmental benefits. Despite these benefits, 3D printing with plant-protein-based materials present significant challenges because there is a lack of a comprehensive study that takes into account the most relevant aspects of the processes involved in producing plant-protein-based printable items. This review takes into account the multi-dimensional aspects of processes that lead to the formulation of successful printable products which includes an understanding of rheological characteristics of plant proteins and 3D-printing parameters, as well as elucidating the appropriate concentration and structural hierarchy that are required to maintain stability of the substrate after printing. This review also highlighted the significant and most recent research on 3D food printing with a wide range of plant proteins. This review also suggests a future research direction of 3D printing with plant proteins.

Current and emerging applications of carrageenan in the food industry

Carrageenan, a polysaccharide derived from red algae, has a long history of use as a food additive in food. Carrageenan comes in three classes, κ-, ι-, and λ-carrageenan, with different properties attributed to their organosulfate substitution levels, and their interactions with other food components give rise to properties such as water holding, thickening, gelling, and stabilizing. Over the years, carrageenan has been used in wide variety of food products such as meat, dairy, and flour-based products, and their mechanisms and functions in these matrices have also been studied. With the emergence of novel food technologies, carrageenan's potential applications have been extensively explored alongside, including encapsulation, edible films/coatings, plant-based analogs, and 3D/4D printing. As the food technology evolves, the required functions of food ingredients have changed, and carrageenan is being investigated for its role in these new areas. However, there are many similarities in the use of carrageenan in both classic and emerging applications, and understanding the underlying principles of carrageenan will lead to a proper use of carrageenan in emerging food products. This review focuses on the potential of carrageenan as a food ingredient in these emerging technologies mainly based on papers published within the past five years, highlighting its functions and applications to better understand its role in food products.

Extraction, functionality, and applications of Chlorella pyrenoidosa protein/peptide

Chlorella pyrenoidosa (C. pyrenoidosa) has been widely used in commercial food and feed production for numerous years. Its high protein content and cost-effectiveness make it an attractive source of novel protein. With a focus on sustainable development and the search for green natural products, current research is dedicated to maximizing the utilization of C. pyrenoidosa protein (CPP) and peptide. Various techniques, such as the use of ionic liquids, freeze-thawing, ultrasonication, enzyme digest, microwaving are employed in the extraction of CPP. The extracted CPP has demonstrated antioxidant, anti-inflammatory, and bacteriostatic properties. It can also stimulate immune regulation, prevent cardiovascular disease, protect red blood cells, and even be used in wastewater treatment. Furthermore, CPP has shown some potential in combating obesity. Additionally, CPP is being explored in three-dimensional (3D) printing applications, particularly for the creation of biological scaffolds. It is also anticipated to play a role in 3D food printing. This review aimed to supply a comprehensive summary of CPP and C. pyrenoidosa peptide extraction methods, their functions, and practical applications in various industries. By doing so, it seeks to underpin subsequent research efforts, highlight current research limitations, and identify future research directions in this field.

Four-Dimensional (4D) Printing of Dynamic Foods-Definitions, Considerations, and Current Scientific Status

Since its conception, the application of 3D printing in the structuring of food materials has been focused on the processing of novel material formulations and customized textures for innovative food applications, such as personalized nutrition and full sensory design. The continuous evolution of the used methods, approaches, and materials has created a solid foundation for technology to process dynamic food structures. Four-dimensional food printing is an extension of 3D printing where food structures are designed and printed to perform time-dependent changes activated by internal or external stimuli. In 4D food printing, structures are engineered through material tailoring and custom designs to achieve a transformation from one configuration to another. Different engineered 4D behaviors include stimulated color change, shape morphing, and biological growth. As 4D food printing is considered an emerging application, imperatively, this article proposes new considerations and definitions in 4D food printing. Moreover, this article presents an overview of 4D food printing within the current scientific progress, status, and approaches.

Preparation and Product Characterization of Microwaveable Food Using Lentinus edodes Protein through 3D Printing

The Lentinus edodes protein (LP) is a high-quality protein known for its well-balanced amino acid composition. In this study, we developed three-dimensional (3D)-printed microwaveable food using a combination of LP and potato flour, and optimized the formulation to achieve a ratio of LP: potato flour: xanthan gum: water = 2:8:1:23. The 3D-printed samples exhibited better shape, weight, and size compared to the molded samples after microwave treatment, with the most favorable microwave effect observed at a 90% filling ratio. The LP content affected the viscosity and retrogradation value of the LP-potato starch mixture. Microwave duration affected the surface hardness, interior softness, and moisture content of the product. The highest overall score of 8.295 points was obtained with a microwave processing duration of 2 min. This study lays a foundation for the development of LP-based 3D-printed food.

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.

Rheological properties, gel properties and 3D printing performance of soy protein isolate gel inks added with different types of apricot polysaccharides

A soybean protein isolate (SPI)-apricot polysaccharide gel with hypolipidemic activity that can be used for 3D printing was prepared and the mechanism of its gel formation was studied in this work. The results demonstrated that adding apricot polysaccharide to SPI could effectively improve the bound water content, viscoelastic properties and rheological properties of the gels. Low-field NMR, FT-IR spectroscopy and surface hydrophobicity confirmed that the interactions between SPI and apricot polysaccharide were mainly realized by electrostatic interactions, hydrophobic and hydrogen bonding. Furthermore, adding modified polysaccharide treated by ultrasonic-assisted Fenton method to SPI on the basis of low-concentration apricot polysaccharide contributed to improving the 3D printing accuracy and stability of the gel. Consequently, the gel formed by adding apricot polysaccharide (0.5 %, m/v) and modified polysaccharide (0.1 %, m/v) to SPI had the best hypolipidemic activity (the binding rate of sodium taurocholate and sodium glycocholate were 75.33 % and 72.86 %, respectively) and 3D printing characteristics.

Recent advances in exploiting carrageenans as a versatile functional material for promising biomedical applications

Carrageenans are a group of biopolymers widely found in red seaweeds. Commercial carrageenans have been traditionally used as emulsifiers, stabilizers, and thickening and gelling agents in food products. Carrageenans are regarded as bioactive polysaccharides with disease-modifying and microbiota-modulating activities. Novel biomedical applications of carrageenans as biocompatible functional materials for fabricating hydrogels and nanostructures, including carbon dots, nanoparticles, and nanofibers, have been increasingly exploited. In this review, we describe the unique structural characteristics of carrageenans and their functional relevance. We summarize salient physicochemical features, including thixotropic and shear-thinning properties, of carrageenans. Recent results from clinical trials in which carrageenans were applied as both antiviral and antitumor agents and functional materials are discussed. We also highlight the most recent advances in the development of carrageenan-based targeted drug delivery systems with various pharmaceutical formulations. Promising applications of carrageenans as a bioink material for 3D printing in tissue engineering and regenerative medicine are systematically evaluated. We envisage some key hurdles and challenges in the commercialization of carrageenans as a versatile material for clinical practice. This comprehensive review of the intimate relationships among the structural features, unique rheological properties, and biofunctionality of carrageenans will provide novel insights into their biomedicine application potential.

Control of Beany Flavor from Soybean Protein Raw Material in Plant-Based Meat Analog Processing

The development of plant-based meat analogs is currently hindered by the beany flavor generated by raw soybean protein and extrusion processing. Wide concern has led to extensive research on the generation and control of this unwanted flavor, as an understanding of its formation in raw protein and extrusion processing and methods through which to control its retention and release are of great significance for obtaining ideal flavor and maximizing food quality. This study examines the formation of beany flavor during extrusion processing as well as the influence of interaction between soybean protein and beany flavor compounds on the retention and release of the undesirable flavor. This paper discusses ways to maximize control over the formation of beany flavor during the drying and storage of raw materials and methods to reduce beany flavor in products by adjusting extrusion parameters. The degree of interaction between soybean protein and beany compounds was found to be dependent on conditions such as heat treatment and ultrasonic treatment. Finally, future research directions are proposed and prospected. This paper thus provides a reference for the control of beany flavor during the processing, storage, and extrusion of soybean raw materials used in the fast-growing plant-based meat analog industry.

Progress in Extrusion-Based Food Printing Technology for Enhanced Printability and Printing Efficiency of Typical Personalized Foods: A Review

Three-dimensional printing technology enables the personalization and on-demand production of edible products of individual specifications. Four-dimensional printing technology expands the application scope of 3D printing technology, which controllably changes the quality attributes of 3D printing products over time. The concept of 5D/6D printing technology is also gradually developing in the food field. However, the functional value of food printing technology remains largely unrealized on a commercial scale due to limitations of printability and printing efficiency. This review focuses on recent developments in breaking through these barriers. The key factors and improvement methods ranging from ink properties and printer design required for successful printing of personalized foods (including easy-to-swallow foods, specially shaped foods, and foods with controlled release of functional ingredients) are identified and discussed. Novel evaluation methods for printability and printing precision are outlined. Furthermore, the design of printing equipment to increase printing efficiency is discussed along with some suggestions for cost-effective commercial printing.

Effects of Texture Modifiers on Physicochemical Properties of 3D-Printed Meat Mimics from Pea Protein Isolate-Alginate Gel Mixture

Meat mimics were prepared from pea protein isolate-alginate gel via 3D printing. The texture of 3D-printed meat mimics was modified by incorporating transglutaminase (TGase) or κ-carrageenan (κc) at 0.3, 0.6 or 0.9% (w/w) into printing material prior to 3D printing. Rheological properties of modified printing material were measured; results were used to support 3D printing results. Textural properties of raw and cooked meat mimics were determined and compared with those of selected animal meats, namely, pork tenderloin, chicken breast, salmon meat and Spanish mackerel. Cooking losses of meat mimics were also determined. G', G″ and tan δ of TGase-modified material were not significantly different from those of the control. In contrast, increasing κc content resulted in increased G' and G″; tan δ of all κc-modified samples decreased from that of the control. Addition of TGase at 0.9% into printing material increased the hardness of raw meat mimics, while κc at 0.9% increased hardness of cooked meat mimics. Raw meat mimics treated with 0.9% TGase exhibited texture closest to raw salmon. Texture of cooked meat mimics treated with 0.9% κc was closest to that of cooked salmon. TGase-treated meat mimics tended to experience lower cooking losses, while κc-treated meat mimics exhibited an opposite trend.

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.

Defects in 3D/4D food printing and their possible solutions: A comprehensive review

3D food printing has recently attracted significant attention, both from academic and industrial researchers, due to its ability to manufacture customized products in such terms as size, shape, texture, color, and nutrition to meet demands of individual consumers. 4D printing, which is a technique that allows evolution of various characteristics/properties of 3D printed objects over time through external stimulation, has also been gaining more attention. In order to produce defect-free printed objects via both 3D and 4D printing, it is necessary to first identify the causes of defects and then their mitigation strategies. Comprehensive review on these important issues is nevertheless missing. The purpose of this review is to investigate causes and characteristics of defects occurring during and/or after 3D food printing, with a focus on how different factors affect the printing accuracy. Various techniques that can potentially minimize or eliminate printing defects and produce high-quality 3D/4D printed food products without the need for time-consuming trial and error printing experiments are critically discussed. Guidelines to avoid defects to improve the efficiency of future 3D/4D printed food production are given.

Application of Protein in Extrusion-Based 3D Food Printing: Current Status and Prospectus

Extrusion-based 3D food printing is one of the most common ways to manufacture complex shapes and personalized food. A wide variety of food raw materials have been documented in the last two decades for the fabrication of personalized food for various groups of people. This review aims to highlight the most relevant and current information on the use of protein raw materials as functional 3D food printing ink. The functional properties of protein raw materials, influencing factors, and application of different types of protein in 3D food printing were also discussed. This article also clarified that the effective and reasonable utilization of protein is a vital part of the future 3D food printing ink development process. The challenges of achieving comprehensive nutrition and customization, enhancing printing precision and accuracy, and paying attention to product appearance, texture, and shelf life remain significant.

Recent Advances in pH-Responsive Freshness Indicators Using Natural Food Colorants to Monitor Food Freshness

Recently, due to the enhancement in consumer awareness of food safety, considerable attention has been paid to intelligent packaging that displays the quality status of food through color changes. Natural food colorants show useful functionalities (antibacterial and antioxidant activities) and obvious color changes due to their structural changes in different acid and alkali environments, which could be applied to detect these acid and alkali environments, especially in the preparation of intelligent packaging. This review introduces the latest research on the progress of pH-responsive freshness indicators based on natural food colorants and biodegradable polymers for monitoring packaged food quality. Additionally, the current methods of detecting food freshness, the preparation methods for pH-responsive freshness indicators, and their applications for detecting the freshness of perishable food are highlighted. Subsequently, this review addresses the challenges and prospects of pH-responsive freshness indicators in food packaging, to assist in promoting their commercial application.

3D Food Printing Applications Related to Dysphagia: A Narrative Review

Dysphagia is a condition in which the swallowing mechanism is impaired. It is most often a result of a stroke. Dysphagia has serious consequences, including choking and aspiration pneumonia, which can both be fatal. The population that is most affected by it is the elderly. Texture-modified diets are part of the treatment plan for dysphagia. This bland, restrictive diet often contributes to malnutrition in patients with dysphagia. Both energy and protein intake are of concern, which is especially worrying, as it affects the elderly. Making texture-modified diets more appealing is one method to increase food intake. As a recent technology, 3D food printing has great potential to increase the appeal of textured foods. With extrusion-based printing, both protein and vegetable products have already been 3D printed that fit into the texture categories provided by the International Dysphagia Diet Standardization Initiative. Another exciting advancement is 4D food printing which could make foods even more appealing by incorporating color change and aroma release following a stimulus. The ultra-processed nature of 3D-printed foods is of nutritional concern since this affects the digestion of the food and negatively affects the gut microbiome. There are mitigating strategies to this issue, including the addition of hydrocolloids that increase stomach content viscosity and the addition of probiotics. Therefore, 3D food printing is an improved method for the production of texture-modified diets that should be further explored.

Research progress in fluid and semifluid microwave heating technology in food processing

Microwave is a form of electromagnetic radiation that has high penetration and heating efficiency in food processing. Uneven heating is the main problem of microwave processing, especially in solid foods. Fluid and semifluid media, which are good carriers in microwave processing, have uniform dielectric properties and good material fluidity. Herein, we review the development, application prospects, and limitations of microwave in fluid and semifluid food processing and the research progress in microwave heating with steam as carrier. The mixture of generated steam and tiny micro droplets from food material under the action of microwave can absorb microwave and transfer heat evenly, which effectively improves the uniformity of microwave heating. Due to the relatively uniform dielectric properties and consistent texture of fluid and semifluid food materials, uneven heating phenomenon during their microwave processing can be significantly inhibited. Based on the development of microwave heating technology and equipment design, the microbial inactivation and enzyme inhibition in fluid and semifluid food were improved and food product with better retention of nutrients and sensory profile were produced. Also, microwave radiation can be used to prepare the printing material or process the printed product for 3D food printing, which enhances the added value of 3D printed products and the personalization of food manufacturing. In future research, intelligent control technology can be applied in the microwave processing of fluid and semifluid food materials for various applications. Therefore, the processing conditions can be adjusted automatically.

Something to chew on: technological aspects for novel snacks

Snacks have accompanied people for a long time, meeting our needs for something fast and filling between meals. Societies and technologies have changed, and so have snacks, adapting to people's daily lives, concerns, and demands. Although traditional snacks, such as potato chips, are still ubiquitous and popular worldwide, there is not unanimity around them anymore, since many people have been looking for healthier snacks. Studies have been carried out to propose healthier snack options by changing their composition and/or techniques to produce them, minimizing contents of energy-dense components and/or maximizing the retention or bioavailability of nutrients. This mini-review presents the main trends on development of snacks and future perspectives. © 2021 Society of Chemical Industry.

Progress in 4D/5D/6D printing of foods: applications and R&D opportunities

4D printing is a result of 3D printing of smart materials which respond to diverse stimuli to produce novel products. 4D printing has been applied successfully to many fields, e.g., engineering, medical devices, computer components, food processing, etc. The last two years have seen a significant increase in studies on 4D as well as 5D and 6D food printing. This paper reviews and summarizes current applications, benefits, limitations, and challenges of 4D food printing. In addition, the principles, current, and potential applications of the latest additive manufacturing technologies (5D and 6D printing) are reviewed and discussed. Presently, 4D food printing applications have mainly focused on achieving desirable color, shape, flavor, and nutritional properties of 3D printed materials. Moreover, it is noted that 5D and 6D printing can in principle print very complex structures with improved strength and less material than do 3D and 4D printing. In future, these new technologies are expected to result in significant innovations in all fields, including the production of high quality food products which cannot be produced with current processing technologies. The objective of this review is to identify industrial potential of 4D printing and for further innovation utilizing 5D and 6D printing.

Application of carbon dots in food preservation: a critical review for packaging enhancers and food preservatives

Carbon dots (CDs) have two unique advantages: one is ease of synthesis at low price, the other is desirable physical and chemical properties, such as ultra-small size, abundant surface functional groups, nontoxic/low-toxicity, good biocompatibility, excellent antibacterial and antioxidant activities etc. These advantages provide opportunities for the development of new food packaging enhancers and food preservatives. This paper systematically reviews the studies of CDs used to strengthen the physical properties of food packaging, including strengthen mechanical strength, ultraviolet (UV) barrier properties and water barrier properties. It also reviews the researches of CDs used to fabricate active packaging with antioxidant and/or antibacterial properties and intelligent packaging with the capacity of sensing the freshness of food. In addition, it analyzes the antioxidant and antibacterial properties of CDs as preservatives, and discusses the effect of CDs applied as coating agents and nano-level food additives for extension the shelf life of food samples. It also provides a brief review on the security and the release behavior of CDs.

Nutritional Function and Flavor Evaluation of a New Soybean Beverage Based on Naematelia aurantialba Fermentation

The soy beverage is a healthy product rich in plant protein; however, its unpleasant flavor affects consumer acceptance. The aim of this study was to determine the feasibility of using Naematelia aurantialba as a strain for the preparation of fermented soybean beverages (FSB). Increases in Zeta potential, particle size, and viscosity make soy beverages more stable. We found that nutrient composition was increased by fermenting N. aurantialba, and the antioxidant activity of soybean beverages significantly increased after 5 days of fermentation. By reducing the content of beany substances such as hexanal and increasing the content of 1-octen-3-ol, the aroma of soybean beverages fermented by N. aurantialba changed from “beany, green, and fatty” to “mushroom and aromatic”. The resulting FSB had reduced bitterness but considerably increased sourness while maintaining the fresh and sweet taste of unfermented soybean beverages (UFSB). This study not only provides a theoretical basis for the market promotion of FSB but also provides a reference for basidiomycetes-fermented beverages.

Chitosan and Whey Protein Bio-Inks for 3D and 4D Printing Applications with Particular Focus on Food Industry

The application of chitosan (CS) and whey protein (WP) alone or in combination in 3D/4D printing has been well considered in previous studies. Although several excellent reviews on additive manufacturing discussed the properties and biomedical applications of CS and WP, there is a lack of a systemic review about CS and WP bio-inks for 3D/4D printing applications. Easily modified bio-ink with optimal printability is a key for additive manufacturing. CS, WP, and WP-CS complex hydrogel possess great potential in making bio-ink that can be broadly used for future 3D/4D printing, because CS is a functional polysaccharide with good biodegradability, biocompatibility, non-immunogenicity, and non-carcinogenicity, while CS-WP complex hydrogel has better printability and drug-delivery effectivity than WP hydrogel. The review summarizes the current advances of bio-ink preparation employing CS and/or WP to satisfy the requirements of 3D/4D printing and post-treatment of materials. The applications of CS/WP bio-ink mainly focus on 3D food printing with a few applications in cosmetics. The review also highlights the trends of CS/WP bio-inks as potential candidates in 4D printing. Some promising strategies for developing novel bio-inks based on CS and/or WP are introduced, aiming to provide new insights into the value-added development and commercial CS and WP utilization.