High-moisture extruded protein fiber formation toward plant-based meat substitutes applications: Science, technology, and prospect

Formation of acrylamide in commercially available plant-based meat alternatives during domestic cooking

The formation and occurrence of acrylamide in carbohydrate-rich foods has been extensively studied over the course of the past few decades. However, the emergence of plant-based meat alternatives presents a new challenge in this field. The aim of this study was to evaluate the levels of acrylamide in commercially available plant-based meat alternatives before and after heat treatment. Trace levels of acrylamide were detected in all samples before heat-treatment, while the concentrations increased in 11 samples out of 16 after heat-treatment. The highest concentration of acrylamide increased from 65.7 ± 6.6 µg kg-1 before to 119 ± 12 µg kg-1 after heat-treatment. Principal component analysis (PCA) indicated that besides macronutrient composition, the use of additives and processing techniques have a strong influence on acrylamide formation in plant-based meat alternatives. The latter was supported by the analysis of self-made meat alternative models that were prepared using only the base ingredients.

Interfacial and foaming properties of plant and microbial proteins: Comparison of structure-function behavior of different proteins

Many plant proteins are amphiphilic molecules that can adsorb to air-water interfaces and form protective coatings around gas bubbles. In this study, the composition, structure, physicochemical properties, air-water interfacial properties, and foaming properties of 16 plant and microbial proteins were characterized. We found a correlation between the composition, structure, physicochemical properties, and foaming properties of the proteins. The foaming capacity of them showed a highly significant positive correlation (p ≤ 0.01) with their foaming stability, α-helix content, surface hydrophobicity, and free sulfhydryl content. The foaming capacity and foaming stability showed highly significant negative correlations with disulfide bond content (p ≤ 0.01). We found wheat gluten protein (WGP) and mung bean protein (MBP) had higher foaming capacity (102.67 ± 8.08 % and 89.33 ± 4.72 %), which could be attributed to higher surface hydrophobicity (179.68 ± 1.40 and 130.28 ± 1.41) and larger contact angle (82.369 ± 0.016° and 82.949 ± 0.228°).

Unveiling the potential of bean proteins: Extraction methods, functional and structural properties, modification techniques, physiological benefits, and diverse food applications

Bean proteins, known for their sustainability, versatility, and high nutritional value, represent a valuable yet underutilized resource, receiving less industrial attention compared to soy and pea proteins. This review examines the structural and molecular characteristics, functional properties, amino acid composition, nutritional value, antinutritional factors, and digestibility of bean proteins. Their applications in various food systems, including baked goods, juice and milk substitutes, meat alternatives, edible coatings, and 3D printing inks, are discussed. The physiological benefits of bean proteins, such as antidiabetic, cardioprotective, antioxidant, and neuroprotective effects, are also presented, highlighting their potential for promoting well-being. Our review emphasizes the diversity of bean proteins and highlights ultrasound as the most effective extraction method among available techniques. Beyond their physiological benefits, bean proteins significantly enhance the structural, technological, and nutritional properties of food systems. The functionality can be further improved through various modification techniques, thereby expanding their applicability in the food industry. While studies have explored the impact of bean protein structure on their nutritional and functional properties, further research is needed to investigate advanced modification techniques and the structure-function relationship. This will enhance the utilization of bean proteins in innovative and sustainable food applications.

Binding and distribution regularity of water molecules in high-moisture textured Antarctic krill (Euphausia superba) meat

High-moisture extrusion technique with the advantage of high efficiency and low energy consumption is a promising strategy for processing Antarctic krill meat. Consequently, this study aimed to prepare high-moisture textured Antarctic krill meat (HMTAKM) with a rich fiber structure at different water contents (53 %, 57 %, and 61 %) and to reveal the binding and distribution regularity of water molecules, which is closely related to the fiber structure of HMTAKM and has been less studied. The hydrogen-bond network results indicated the presence of at least two or more types of water molecules with different hydrogen bonds. Increasing the water content of HMTAKM promoted the formation of hydrogen bonds between the water molecules and protein molecules, leading to the transition of the β-sheet to the α-helix. These findings offer a novel viable processing technique for Antarctic krill and a new understanding of the fiber formation of high-moisture textured proteins.

Tenderness in meat and meat alternatives: Structural and processing fundamentals

The demand for meat alternatives based on ingredients sourced from nonanimal materials with equivalent quality of muscle tissue is increasing. As more consumers switch to meat alternatives, a growing body of research has investigated the tenderness and related texture attributes in plant-based meats to increase consumer acceptance. A deeper understanding of tenderness including the differences and similarities between meat and meat alternatives is crucial to developing products that meet consumer expectations, as it directly influences consumer acceptance. Meat tenderness is commonly quantified using sensory evaluation and instrumental tests and is influenced by various factors such as the intrinsic features of the animal before the slaughter, naturally occurring proteolysis during the post-slaughter process, and several tenderization techniques. In contrast, meat alternative tenderness can be actively tailored through the selection of ingredients and the operating conditions of the structuring process. Especially, extrusion parameters such as moisture content and barrel temperature can greatly modulate tenderness-related attributes. Postprocessing methods that have traditionally been utilized for tenderizing have also been applied to meat alternatives, but more studies are needed to fully reveal the underlying mechanisms. This review offers an overview and critical discussion on tenderness, covering the structural origins, influencing factors, analytical methods, oral processing, and tenderization processes for both meat and meat alternatives. The discussion is based on the existing knowledge of muscle tissue, which evolves to critically reviewing how this understanding can be applied to the textural attributes of meat alternatives and what kind of novel tenderization techniques can be developed for these new sustainable food products.

Environmental concerns on water-soluble and biodegradable plastics and their applications - A review

Water-soluble polymers are materials rapidly growing in volume and in number of materials and applications. Examples include synthetic plastics such as polyacrylamide, polyacrylic acid, polyethylene glycol, polyethylene oxide and polyvinyl alcohol, with applications ranging from cosmetics and paints to water purification, pharmaceutics and food packaging. Despite their abundance, their environmental concerns (e.g., bioaccumulation, toxicity, and persistence) are still not sufficiently assessed, especially since water soluble plastics are often not biodegradable, due to their chemical structure. This review aims to overview the most important water-soluble and biodegradable polymers, their applications, and their environmental impact. Degradation products from water-insoluble polymers designed for biodegradation can also be water soluble. Most water-soluble plastics are not immediately harmful for humans and the environment, but the degradation products are sometimes more hazardous, e.g. for polyacrylamide. An increased use of water-soluble plastics could also introduce unanticipated environmental hazards. Therefore, excessive use of water-soluble plastics in applications where they can enter the environment should be discouraged. Often the plastics can be omitted or replaced by natural polymers with lower risks. It is recommended to include non-biodegradable water-soluble plastics in regulations for microplastics, to make risk assessments for different water-soluble plastics and to develop labels for flushable materials.

Perforated imprinting on high moisture meat analogue confers long range mechanical anisotropy resembling meat cuts

Meat cuts, when cooked and masticated, separate into fibrous structures because of the long-range mechanical anisotropy (LMA) exhibited by muscle fascicles, which is not fully recapitulated in alternative proteins produced using molecular alignment technology like high moisture extrusion. We have developed a scalable perforated micro-imprinting technology to greatly enhance LMA in high moisture meat analogue (HMMA). By imprinting 1 mm thick HMMA sheets with perforated patterns (optimized by AI), we observed up to 5 × more anisotropic separation of fibrous structures in a one-dimensional pulling LMA analysis, to match the fibrousness of the cooked chicken breast, duck breast, pork loin and beef loin. We stacked and bound imprinted sheets with transglutaminase (TG) to produce imprinted whole-cuts. Controlling fiber separation in the imprinted cuts achieved hardness ranging from 6578 g to 18467 g (2 cm × 2 cm × 1 cm, 50% strain), which matched meats from different species. Imprinted cuts improved meat-like fiber separation over HMMA when masticated, measured by Euclidean distances (0.057 and 0.106 respectively) to animal meat cuts on image features. In sensory evaluation, imprinted cuts improved consumer acceptance by 33.3% and meat-like fibrousness by 20%, by significantly enhancing the HMMA appearance, texture, and mouthfeel.

Transforming plant proteins into plant-based meat alternatives: challenges and future scope

The global transition towards sustainable living has led to a growing demand for innovative food products that enhance environmental sustainability. Traditional meat production is known for its high energy consumption and significant carbon emissions, necessitating alternative approaches. Plant-based meat (PBM) offers a promising solution to reduce the ecological footprint of animal agriculture. This paper examines various challenges in PBM development, including nutritional equivalence, industrial scalability, organoleptic properties, and digestibility. Addressing these challenges requires interdisciplinary collaboration to ensure consumer acceptance, regulatory compliance, and environmental stewardship. Advanced technologies like nanotechnology, fermentation, and enzymatic hydrolysis, along with automation and repurposing cattle farms, offer solutions to enhance PBM's quality and production efficiency. By integrating these innovations, PBM has the potential to revolutionize the food industry, offering sustainable and nutritious alternatives that meet global dietary needs while significantly reducing environmental impact.

Graphical abstract

Plant-based Meat Analogs: Perspectives on Their Meatiness, Nutritional Profile, Environmental Sustainability, Acceptance and Challenges

PURPOSE OF REVIEW

Plant-based meat analogs (PBMAs) have been the subject of interest over the past few years due to consumers' demand for environmentally friendly, healthful, and non-animal-based foods. A better comprehension of the composition, structure, texture, nutrition, and sustainability of these PBMAs is necessary.

RECENT FINDINGS

This review articulates the protein sources and composition of PBMAs and their "meatiness" with respect to texture, structure, and flavor enhancement. The components used in the analogs, such as unsaturated fats, fibers, vitamins, minerals, carbohydrates, and plant-based oils enriching their nutritional profile, are described. The study identifies the environmental and sustainability impact of PBMAs, as crucial to the survival and maintenance of biodiversity. More studies are warranted to scope and underscore the significance of the analogs and comprehend the texture or structure-function relationships. Further product development and testing thereof may ultimately result in quality meat analogs that respect meat taste, health and acceptance of consumers, environmental sustainability, animal welfare, and current challenges.

Advancing molecular understanding in high moisture extrusion for plant-based meat analogs: Challenges and perspectives

In recent years, meat analogs based on plant proteins have received increasing attention. However, the process of high moisture extrusion (HME), the method for their preparation, has not been thoroughly explored, particularly in terms of elucidating the complex interactions that occur during extrusion, which remain challenging. These interactions arise from the various ingredients added during HME, including proteins, starches, edible gums, dietary fibers, lipids, and enzymes. These ingredients undergo intricate conformational changes and interactions under extreme conditions of high temperature, pressure, and shear, ultimately forming the fibrous structure of meat analogs. This review offers a overview of these ingredients and the molecular interaction changes they undergo during the extrusion process. Additionally, it delves into the major molecular interactions such as disulfide bonding, hydrogen bonding, and hydrophobic interactions, providing detailed insights into each.

Unraveling the impact of thermal modulation in heating and cooling dies on the fibrous structure of high-moisture meat alternatives

We aimed to create high-moisture plant-based meat alternatives (HPMAs) that closely mimic the fibrous structure found in conventional meat. To achieve this goal, we focused on the impact of modulating the heating and cooling die temperatures during the extrusion process on the structural properties of HPMAs. The optimal temperatures for the heating and cooling dies were determined to be 160 and 50 °C, respectively, following a comprehensive analysis of various quality characteristics. These included assessments of cutting strength, texturization degree, moisture content, and microstructure. Analyzing the correlation coefficients between heating and cooling die temperatures and the quality characteristics of HPMAs revealed that modulating the cooling die temperature has a greater impact on quality characteristics than modulating the heating die temperature. The quality characteristics of HPMAs were also compared with those of boiled and sous-vide cooked chicken breasts. The optimal HPMA exhibited the most similar fibrous macro- and micro-structure to sous-vide cooked chicken breast. Consequently, our study highlights the importance of modulating the heating die and cooling die temperatures, among various process parameters of high-moisture extrusion cooking, which is crucial for producing HPMAs closely resembling conventional meat.

Toward Diverse Plant Proteins for Food Innovation

This review highlights the development of plant proteins from a wide variety of sources, as most of the research and development efforts to date have been limited to a few sources including soy, chickpea, wheat, and pea. The native structure of plant proteins during production and their impact on food colloids including emulsions, foams, and gels are considered in relation to their fundamental properties, while highlighting the recent developments in the production and processing technologies with regard to their impacts on the molecular properties and aggregation of the proteins. The ability to quantify structural, morphological, and rheological properties can provide a better understanding of the roles of plant proteins in food systems. The applications of plant proteins as dairy and meat alternatives are discussed from the perspective of food structure formation. Future directions on the processing of plant proteins and potential applications are outlined to encourage the generation of more diverse plant-based products.

Impact of Extrusion Parameters on the Formation of Nε-(Carboxymethyl)lysine, Nε-(Carboxyethyl)lysine and Acrylamide in Plant-Based Meat Analogues

To investigate the impact of extrusion parameters on the formation of Nε-(carboxymethyl)lysine (CML), Nε-(carboxyethyl)lysine (CEL) and acrylamide in plant-based meat analogues (PBMAs), the content changes and the correlations of compounds related to their formation were studied. The extrusion promoted CML, CEL and acrylamide formation, with more CEL being formed than CML. Variations in the moisture level and barrel temperature exerted a greater influence on the CML, CEL, acrylamide and α-dicarbonyl compounds than the screw speed and the feed rate. An increase in the moisture content led to a decrease in the CEL content, whereas it enhanced CML formation. The impact of moisture on acrylamide formation varied depending on whether low- or high-moisture extrusion was applied. Elevated temperatures promoted the accumulation of CEL, methylglyoxal and 2,3-butanedione while diminishing the accumulation of CML, acrylamide, glyoxal and 3-deoxyglucosone. CML and CEL were positively correlated with glyoxal and methylglyoxal, respectively. CEL and methylglyoxal were negatively correlated with protein and water content, whereas CML, glyoxal and 3-deoxyglucosone displayed positive correlations. In summary, higher moisture levels and feed rates and lower screw speeds and barrel temperatures are advantageous for producing PBMAs with lower CEL and total advanced glycation end-products contents, while lower or higher moisture contents, a lower feed rate and a higher barrel temperature are beneficial to reducing the acrylamide content.

Advancements in plant based meat analogs enhancing sensory and nutritional attributes

The burgeoning demand for plant-based meat analogs (PBMAs) stems from environmental, health, and ethical concerns, yet replicating the sensory attributes of animal meat remains challenging. This comprehensive review explores recent innovations in PBMA ingredients and methodologies, emphasizing advancements in texture, flavor, and nutritional profiles. It chronicles the transition from soy-based first-generation products to more diversified second- and third-generation PBMAs, showcasing the utilization of various plant proteins and advanced processing techniques to enrich sensory experiences. The review underscores the crucial role of proteins, polysaccharides, and fats in mimicking meat's texture and flavor and emphasizes research on new plant-based sources to improve product quality. Addressing challenges like production costs, taste, texture, and nutritional adequacy is vital for enhancing consumer acceptance and fostering a more sustainable food system.

Possibility of Isolated Mung Bean Protein as a Main Raw Material in the Production of an Extruded High-Moisture Meat Analog

As consumer demand for meat analogs continues to grow, various plant proteins are being explored for their production. This study uses isolated mung bean protein (IMBP) to replace isolated soy protein (ISP), investigating the effects of IMBP content (0%, 10%, 20%, 30%, 40%, and 50%) on the physicochemical and textural properties of high-moisture meat analogs (HMMAs) and exploring the potential of IMBP in the development and production of meat analogs. The results show that IMBP can bind water and cause protein denaturation, thus requiring more time and higher temperatures to be formed compared to HMMAs without IMBP. Additionally, increasing the IMBP content improves the gelling ability, thereby increasing the input of specific mechanical energy. As the IMBP content increases, the fibrous structure of the HMMA also increases. When the IMBP content reaches 40-50%, the most meat-like fibrous structure is observed. The water-holding capacity, water absorption capacity, springiness, and cohesiveness are negatively correlated with the IMBP content, while the oil absorption capacity is positively correlated with it. The integrity index and nitrogen solubility index show opposite trends with the increase in the IMBP content. When the IMBP content is 50%, the springiness and chewiness are the lowest, and the cutting strength is also the lowest, but the sample has a rich fibrous content, indicating that the HMMA with 50% IMBP content is soft and juicy. In conclusion, IMBP has the potential to be a substitute for ISP in the production of HMMAs.

Development of plant-based whole egg analogs using emulsion technology

RuBisCO is a plant protein that can be derived from abundant and sustainable natural resources (such as duckweed), which can be used as both an emulsifying and gelling agent. Consequently, it has the potential to formulate emulsion gels that can be used for the development of plant-based replacements of whole eggs. In this study, we investigated the ability of RuBisCO-based emulsion gels to mimic the desirable properties of whole eggs. The emulsion gels contained 12.5 wt% RuBisCO and 10 wt% corn oil to mimic the macronutrient composition of real whole eggs. Initially, an oil-in-water emulsion was formed, which was then heated to convert it into an emulsion gel. The impact of oil droplet diameter (∼15, 1, and 0.2 μm) on the physicochemical properties of the emulsion gels was investigated. The lightness and hardness of the emulsion gels increased as the droplet size decreased, which meant that their appearance and texture could be modified by controlling droplet size. Different concentrations of curcumin (3, 6, and 9 mg/g oil) were incorporated into the emulsions using a pH-driven approach. The curcumin was used as a natural dual functional ingredient (colorant and nutraceutical). The yellow-orange color of curcumin allowed us to match the appearance of raw and cooked whole eggs. This study shows that whole egg analogs can be formulated using plant-based emulsion gels containing natural pigments.

Alien introgression to wheat for food security: functional and nutritional quality for novel products under climate change

Crop yield and quality has increased globally during recent decades due to plant breeding, resulting in improved food security. However, climate change and shifts in human dietary habits and preferences display novel pressure on crop production to deliver enough quantity and quality to secure food for future generations. This review paper describes the current state-of-the-art and presents innovative approaches related to alien introgressions into wheat, focusing on aspects related to quality, functional characteristics, nutritional attributes, and development of novel food products. The benefits and opportunities that the novel and traditional plant breeding methods contribute to using alien germplasm in plant breeding are also discussed. In principle, gene introgressions from rye have been the most widely utilized alien gene source for wheat. Furthermore, the incorporation of novel resistance genes toward diseases and pests have been the most transferred type of genes into the wheat genome. The incorporation of novel resistance genes toward diseases and pests into the wheat genome is important in breeding for increased food security. Alien introgressions to wheat from e.g. rye and Aegilops spp. have also contributed to improved nutritional and functional quality. Recent studies have shown that introgressions to wheat of genes from chromosome 3 in rye have an impact on both yield, nutritional and functional quality, and quality stability during drought treatment, another character of high importance for food security under climate change scenarios. Additionally, the introgression of alien genes into wheat has the potential to improve the nutritional profiles of future food products, by contributing higher minerals levels or lower levels of anti-nutritional compounds into e.g., plant-based products substituting animal-based food alternatives. To conclude, the present review paper highlights great opportunities and shows a few examples of how food security and functional-nutritional quality in traditional and novel wheat products can be improved by the use of genes from alien sources, such as rye and other relatives to wheat. Novel and upcoming plant breeding methods such as genome-wide association studies, gene editing, genomic selection and speed breeding, have the potential to complement traditional technologies to keep pace with climate change and consumer eating habits.

High-Moisture Extrusion of Plant Proteins: Fundamentals of Texturization and Applications

The growing demand for sustainable and healthy food alternatives has led to a significant increase in interest in plant-based protein products. Among the various techniques used in creating meat analogs, high-moisture extrusion (HME) stands out as a promising technology for developing plant-based protein products that possess desirable texture and mouthfeel. During the extrusion process, plant proteins undergo a state transition, causing their rheological properties to change, thereby influencing the quality of the final extrudates. This review aims to delve into the fundamental aspects of texturizing plant proteins using HME, with a specific focus on the rheological behavior exhibited by these proteins throughout the process. Additionally, the review explores the future of HME from the perspective of novel raw materials and technologies. In summary, the objective of this review is to provide a comprehensive understanding of the potential of HME technology in the development of sustainable and nutritious plant-based protein products.

Technological challenges and future perspectives of plant-based meat analogues: From the viewpoint of proteins

The global demand for high-quality animal protein faces challenges, prompting a surge in interest in plant-based meat analogues (PBMA). PBMA have emerged as a promising solution, although they encounter technological obstacles. This review discusses the technological challenges faced by PBMA from the viewpoint of plant proteins, emphasizing textural, flavor, color, and nutritional aspects. Texturally, PBMA confront issues, such as deficient fibrous structure, chewiness, and juiciness. Addressing meat flavor and mitigating beany flavor in plant protein are imperative. Furthermore, achieving a distinctive red or pink meat color remains a challenge. Plant proteins exhibit a lower content of essential amino acids. Future research directions encompass (1) shaping myofibril fibrous structures through innovative processing; (2) effectively eliminating the beany flavor; (3) developing biotechnological methodologies for leghemoglobin and plant-derived pigments; (4) optimizing amino acid composition to augment the nutritional profiles. These advancements are crucial for utilization of plant proteins in development of high-quality PBMA.

High moisture extrusion of soybean protein isolate: Effect of β-glucan on physicochemical properties of extrudates

This study is focused on exploring the effect of twin-screw high-moisture extrusion technology on the physico-chemical properties of β-glucan-soybean protein isolate (SPI-BG) extrudates. Different proportions (0 %, 1 %, 2 %, 3 %, 4 %, 5 %) of oat β-glucan (BG) were added with soybean protein isolate (SPI) to prepare SPI-BG extrudates. Results showed that the addition of a high quantity of β-glucan (BG) decreased the elastic properties of soy protein isolate (SPI) extrudates and then increased. The strengthening of S1-S2-S3 interactions (hydrogen bonds, hydrophobic interactions, and disulfide bonds) was primarily responsible for this trend. Fourier transform infrared (FTIR) spectral analysis was conducted which revealed that BG did not significant affect random coil content of SPI. However, it was observed that α-helix content was increased significantly and the β-sheet content was decreased. An observation was noted in the value of enthalpy (ΔH) change that increased from 115.80 J/g to 159.68 J/g.

A multihole nozzle controls recrystallization of high-moisture extruded maize starches: Effect of cooling die temperature

Hot extrusion is utilized for starch modification due to its high mechanical input and product output. Amylose recrystallization commences and primarily depends on intermolecular interactions after conventional extrusion. Hence, the design of a new component based on the existed extrusion system was aimed at facilitating molecular aggregation, potentially accelerating starch recrystallization. In this study, a nozzle sheet comprising 89 holes was integrated into the cooling die. The impact of the multihole nozzle on the structure and in vitro digestibility of extruded maize starches after retrogradation was examined at varying cooling die temperatures. The results showed that the nozzle-assembled extrusion system operated effectively without additional mechanical or yield losses. At 50 °C, the crystallinity of nozzle-produced starch was approximately 70 % higher than that of conventionally extruded starch, predominantly owing to the B-type allomorph of the amylose double helix. Recrystallized amylopectin was also found in these nozzle-produced starches, indicating that multihole nozzle-induced uniaxial elongational flow resulted in the rapid starch crystallization. The increased formation of recrystallized amylose led to improved molecular order in starch structures while reducing their digestibility. These findings revealed a new approach to improve starch crystallinity by incorporating a nozzle sheet in the extrusion process.

Flavor of extruded meat analogs: A review on composition, influencing factors, and analytical techniques

Meat analogs are anticipated to alleviate environmental and animal welfare concerns as the demand for meat rises. High moisture extrusion is commonly employed to produce meat analogs, and its flavor could influence consumers' choice. To improve the development and market demand of extruded meat analogs, flavor precursors and natural spices have been used in high moisture extrusion process to directly improve the flavor profile of extruded meat analogs. Although there have been many studies on the flavor of high moisture extruded meat analogs, flavor composition and influencing factors have not been summarized. Thus, this review systematically provides the main pleasant and unpleasant flavor-active substances with 79 compounds, as well as descriptive the influence of flavor-active compounds, chemical reactions (such as lipid oxidation and the Maillard reaction), and fiber structure formation (based on extrusion process, extrusion parameters, and raw materials) on flavor of extruded meat analogs. Flavor evaluation of extruded meat analogs will toward multiple assessment methods to fully and directly characterize the flavor of extruded meat analogs, especially machine learning techniques may help to predict and regulate the flavor characteristics of extruded meat analogs.

High-moisture extrusion of curdlan: Texture and structure

High-moisture extrusion is a promising thermomechanical technology extensively employed in manufacturing fibrous meat analogues from plant-based proteins, garnering considerable research attention. However, polysaccharide-based extrusion has been rarely explored. The present study investigates the effects of varying extruder barrel temperatures (130 °C-200 °C) on the texture and structure of curdlan extrudates, and highlights the formation mechanism. Results showed that the single chain of curdlan aggregates to form triple-helix chains upon extrusion, consequently enhancing the crystallinity, particularly at 170 °C. The hardness, chewiness, and mechanical properties improved with increasing barrel temperature. Moreover, barrel temperatures affected the macrostructure, the extrudates maintained intact morphologies except at 160 °C due to the melting of curdlan gel as confirmed by the differential scanning calorimetry thermogram. Microstructural analysis revealed that curdlan extrudates transited through three phases: original gel (130 °C, 140 °C, and 150 °C), transition state (160 °C), and regenerated gel (170 °C, 180 °C, 190 °C, and 200 °C). The steady state of regenerated gel (170 °C) exhibited higher crystallinity and smaller fractal dimension, resulting in a more compact and crosslinked gel network. This study elucidates the structure transition of curdlan gel at extremely high temperatures, offering valuable technical insights for developing theories and methods with respect to polysaccharide-based extrusion that may find applications in food-related fields.

Towards Sustainable Protein Sources: The Thermal and Rheological Properties of Alternative Proteins

Reducing meat consumption reduces carbon emissions and other environmental harms. Unfortunately, commercial plant-based meat substitutes have not seen widespread adoption. In order to enable more flexible processing methods, this paper analyzes the characteristics of commercially available spirulina, soy, pea, and brown rice protein isolates to provide data for nonmeat protein processing that can lead to cost reductions. The thermal and rheological properties, as well as viscosity, density, and particle size distribution, were analyzed for further study into alternative protein-based food processing. The differential scanning calorimetry analysis produced dry amorphous-shaped curves and paste curves with a more distinct endothermic peak. The extracted linear temperature ranges for processing within food production were 70-90 °C for spirulina, 87-116 °C for soy protein, 67-77 °C for pea protein, and 87-97 °C for brown rice protein. The viscosity analysis determined that each protein material was shear-thinning and that viscosity increased with decreased water concentration, with rice being an exception to the latter trend. The obtained viscosity range for spirulina was 15,100-78,000 cP, 3200-80,000 cP for soy protein, 1400-32,700 cP for pea protein, and 600-3500 cP for brown rice protein. The results indicate that extrusion is a viable method for the further processing of protein isolates, as this technique has a large temperature operating range and variable screw speed. The data provided here can be used to make single or multi-component protein substitutes.

Mechanism of feed moisture levels in extrusion treatment to improve the instant properties of Chinese yam (Dioscorea opposita Thunb.) flour

Extruded yam flour was prepared at different feed moisture to improve its instant properties. The water solubility index (WSI) and water absorption index (WAI) were used to compare the instant properties of yam flour. Their chemical compositions, particle size distribution, crystalline structure, and microscopic forms were also analyzed to assess the effects of feed moisture on the instant properties of yam flour. We found that extrusion significantly improved the instant properties of yam flour, while the WSI value increased from 29.50% to 71.86% and the WAI value decreased from 387.88% to 228.06% with decreased feed moisture. Extrusion led to the degradation of total starch and amylopectin, and the contents of soluble substances increased markedly. Extrusion destroyed the granular and crystalline structures, which were reconstituted as amylose-lipid complexes with a significant decrease in relative crystallinity. Increasing the feed moisture was beneficial to the flow and color retention, while lower feed moisture was more favorable to enhance the instant properties.

Inhibition mechanism of rice glutelin on extruded starch digestion: From the structural properties of starch and enzyme activity

To increase the anti-digestion ability of extruded rice starch (ERS), the influence of rice glutelin (RG) on digestive and structural characteristics of ERS were investigated. The resistant starch content increased from 4.49 % to 18.08 % as the RG content increased, while the digestion rate and digestion velocity constant were reduced by the incorporation of RG. Morphological observations showed that ERS was adhered and encapsulated by RG, and the specific area of starch granules were decreased after the addition of RG. The results of XRD and FTIR suggested that the long-range and short-range orders of ERS were improved due to the complexation with RG. The thickness of crystalline of ERS was increased while its amorphous region thickness was reduced by the supplementation with RG. The 1H NMR and 13C NMR data revealed that the branching degree and double helix content of ERS was increased by 46.24 % and 52.67 % when RG content reached to 12 %. Additionally, the addition of RG altered the molecular weight and chain length distribution of ERS. The α-amylase activity and glucoamylase activity was inhibited by RG. These results could provide a valuable basis for the application of RG in extruded rice starchy foods with lower glycemic index.

The interaction between wheat and pea protein influences the final chemical and sensory characteristics of extruded high moisture meat analogs

Plant-based meat analog products, including those produced by extrusion processing, have become increasingly popular. Complete comprehension of the texturization mechanism and the formation of fibrousness would help improve existing products and extend the variety of plant sources used. Therefore, this study aimed to provide improved insight into the mechanism of texturization during the processing of high-moisture meat analog (HMMA) products. Blends with different wheat and pea protein ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wheat:pea) were extruded at a screw speed of 400 rpm, two different moisture contents (50% and 55%), and a feed rate of 90 g/min using a co-rotating twin-screw extruder. Extrudates were analyzed for their texture, free sulfhydryl groups, disulfide bonds, and solubility in different extractants relative to the raw ingredient blends. In addition, a sensory analysis was conducted using the rapid and cost-effective "rate-all-that-apply" (RATA) methodology. The interplay between the two protein types had synergistic effects on the system parameters torque, pressure, and specific mechanical energy, as well as on some textural and sensory parameters. Molecular analyses were not influenced by the interplay between wheat and pea protein as the molecular analyses followed linear trends with the pea inclusion level. Analysis of protein solubility suggests that the texturization mechanism differs slightly depending on the protein type. It is suggested that the texturization of wheat protein depends highly on disulfide bonds, whereas the texturization of pea protein relies on the combination of disulfide bonds and non-covalent interactions. Additionally, RATA was found to be a valuable tool for HMMA products.

The Potential of Soluble Proteins in High-Moisture Soy Protein-Gluten Extrudates Preparation

In this study, the effects of different soluble proteins, including collagen peptides (CP), soy protein hydrolysate (HSPI), whey protein isolate (WPI), sodium caseinate (SC), and egg white protein (EWP), on the structural and mechanical properties of blends containing soy protein isolate (SPI) and wheat gluten (WG) were investigated using high-moisture extrusion. The addition of CP and HSPI resulted in a more pronounced fibrous structure with increased voids, attributing to their plasticizing effect that enhanced polymer chain mobility and reduced viscosity. WPI, SC, and EWP acted as crosslinking agents, causing early crosslink formation and decreased polymer chain mobility. These structural variations directly influenced the tensile properties of the extrudates, with CP displaying the highest anisotropic index. Moreover, the presence of soluble proteins impacts the permeability of the extrudates. These insights shed light on how soluble proteins can be used to modify the properties of SPI-WG blends, making them suitable for meat analogue production.

Relationship between Soybean Protein Isolate and Textural Properties of Texturized Vegetable Protein

To identify the ideal soybean protein isolate for texturized vegetable protein processing, the effect of different soybean protein isolates on texturized vegetable protein composition was studied. Three different types of soybean protein isolates were selected and analyzed for functional properties (water holding capacity (WHC), emulsifying properties, foaming properties), amino acid content, and protein secondary structure. Then, using the same formulation, the soybean protein isolates were extruded to produce texturized vegetable protein, and its textural properties, degree of texturization, microstructure, free sulfhydryl (free SH), and disulfide (S-S) content were determined. Lastly, a correlation analysis was performed to examine the connection between soybean protein isolates and texturized vegetable proteins. After correlation analysis, the soybean protein isolate functional properties that affect the textural properties of the texturized vegetable protein were as follows: the emulsifying property affected the hardness, adhesiveness, springiness, gumminess, and chewiness of the texturized vegetable proteins; and the foaming property affected the gumminess, chewiness, and the degree of texturization of the texturized vegetable proteins. In addition, 16 amino acids including threonine (Thr), methionine (Met), and arginine (Arg) affect texturized vegetable proteins, mainly with respect to adhesiveness, springiness, and free SH. The effects of secondary structure (α-helix, random coil) on texturized vegetable proteins were degree of texturization, resilience, and cohesion, respectively. Therefore, choosing the soybean protein isolate with better emulsifying and foaming properties provides a more suitable approach for processing texturized vegetable protein.

Changes in physicochemical and structural properties of pea protein during the high moisture extrusion process: Effects of carboxymethylcellulose sodium and different extrusion zones

This study investigated effects of carboxymethylcellulose sodium (CMC) on the conformational evolution of pea protein during the high moisture extrusion process. The morphological observation showed that the addition of CMC facilitated the formation of fibrous structure of pea protein. In comparison with the pea protein in the melting zone and extrudate, the combination of CMC increased the denaturation enthalpy of pea protein by 2.09 % and 2.34 %. Compared with the material in the mixing zone, the degree of grafting between CMC and pea protein in the die was enhanced by 98.95 %. In general, the supplementation of CMC depressed the exposure of hydrophobic groups in the pea protein. In the extrusion barrel, the CMC increased the unfolding of protein molecular chains while it promoted the refolding of protein chains in the die. For the extrudate, the addition of CMC decreased the contents of α-helix and β-sheet of pea protein by 9.67 % and 6.93 % while the contents of β-turn and random coil were increased, leading to changes in the molecular weight distribution of protein molecules. In conclusion, these results provided new strategies toward producing the high-quality pea protein-based meat analogues by adding CMC.

Characterization of texturized meat analogues containing native lupin flour and lupin protein concentrate/isolate

Lupin is a nutritious, yet undervalued grain used as a fodder and food crop. In the present study, native lupin flour (LF), lupin protein concentrate (LPC), and lupin protein isolate (LPI) were combined (70% LPI:LPC blend ratios [30:70, 50:50, and 70:30] and 30% LF constant fraction), extruded at high moisture (45-55%), and shaped with a long cooling die (800 mm) to obtain texturized meat analogues (TMAs) with fibrous structures. The characteristics of TMAs (e.g., hardness, water hydration capacity) depended heavily on water content, blend ratios (LPI:LPC), and to a lesser extent, the long cooling die temperature. Color changes (i.e., L*, b*) were mostly attributed to variations in blend ratios (LPI:LPC). Microstructure analysis showed that TMAs with higher water content (55%) were more likely to have thinner walls and smaller void thickness. Fluorescence imagery revealed that TMAs with lower LPI content presented more homogeneous structures. These findings show that reasonable amounts (30% d.m.) of native lupin flour can be incorporated into meat analogues by maintaining a sufficiently high protein content (>50% d.m.) to trigger the formation of fibrous structures.

A comprehensive review of mung bean proteins: Extraction, characterization, biological potential, techno-functional properties, modifications, and applications

The popularity of plant-based proteins has increased, and mung bean protein (MBP) has gained immense attention due to its high yield, nutritional value, and health benefits. MBP is rich in lysine and has a highly digestible indispensable amino acid score. Dry and wet extractions are used to extract MBP flours and concentrates/isolates, respectively. To enhance the quality of commercial MBP flours, further research is needed to refine the purity of MBPs using dry extraction methods. Furthermore, MBP possesses various biological potential and techno-functional properties, but its use in food systems is limited by some poor functionalities, such as solubility. Physical, biological, and chemical technologies have been used to improve the techno-functional properties of MBP, which has expanded its applications in traditional foods and novel fields, such as microencapsulation, three-dimensional printing, meat analogs, and protein-based films. However, study on each modification technique remains inadequate. Future research should prioritize exploring the impact of these modifications on the biological potential of MBP and its internal mechanisms of action. This review aims to provide ideas and references for future research and the development of MBP processing technology.

Novel plant-based meat alternatives: Implications and opportunities for consumer nutrition and health

Against the backdrop of the global protein transition needed to remain within planetary boundaries, there is an influx of plant-based meat alternatives that seek to approximate the texture, flavor and/or nutrient profiles of conventional animal meat. These novel plant-based meat alternatives, enabled by advances in food technology, can be fundamentally different from the whole-plant foods from which they are derived. One of the reasons is the necessity to use food additives on various occasions, since consumers' acceptance of plant-based meat products primarily depends on the organoleptic properties. Consequently, a high degree of heterogeneity in formulation and nutritional profiles exists both within and between product categories of plant-based meat alternatives with unknown effects on several aspects of human health. This is further complicated by the differences in digestibility and bioavailability between proteins from animal and plant sources, which have a profound impact on colonic fermentation, nutritional adequacy and potential health effects. On the other hand, emerging strategies provide opportunities to develop affordable, delicious and nutritious plant-based meat alternatives that align with consumer interests.

Behavior of enzymes under high pressure in food processing: mechanisms, applications, and developments

High pressure processing (HPP) offers the benefits of safety, uniformity, energy-efficient, and low waste, which is widely applied for microbial inactivation and shelf-life extension for foods. Over the past forty years, HPP has been extensively researched in the food industry, enabling the inactivation or activation of different enzymes in future food by altering their molecular structure and active site conformation. Such activation or inactivation of enzymes effectively hinders the spoilage of food and the production of beneficial substances, which is crucial for improving food quality. This paper reviews the mechanism in which high pressure affects the stability and activity of enzymes, concludes the roles of key enzymes in the future food processed using high pressure technologies. Moreover, we discuss the application of modified enzymes based on high pressure, providing insights into the future direction of enzyme evolution under complex food processing conditions (e.g. high temperature, high pressure, high shear, and multiple elements). Finally, we conclude with prospects of high pressure technology and research directions in the future. Although HPP has shown positive effects in improving the future food quality, there is still a pressing need to develop new and effective combined processing methods, upgrade processing modes, and promote sustainable lifestyles.

Influence of hemin on structure and emulsifying properties of soybean protein isolate

Hemin has potential application value in plant-based meat analogues. However, mechanisms of interaction between hemin and plant protein are unclear. In this study, soy protein isolate (SPI) was applied to examine these interactions using multi-spectroscopic and molecular docking techniques. Additionally, the influence of hemin on emulsification of SPI was also explored. Fluorescence and UV-Vis spectra showed quenching of SPI by hemin was static, resulting in conformation changes on the surface amino acid residues, around which hydrophobicity was significantly reduced from 425.9 ± 16.2 to 108.9 ± 1.8 (p < 0.05). FTIR and CD spectra results suggested the protein secondary structure altered, and the content of α-helix and random coils increased by 1.13% and 1.43%, respectively. Furthermore, emulsifying properties of SPI were strengthened with increased hemin. This work improves our understanding of interactions between SPI and hemin and offer a theoretical basis for application of heme in plant-based meat analogues.

Effects of Process Parameters on the Fibrous Structure and Textural Properties of Calcium Caseinate Extrudates

Textured calcium caseinate extrudates are considered promising candidates in producing fish substitutes. This study aimed to evaluate how the moisture content, extrusion temperature, screw speed, and cooling die unit temperature of the high-moisture extrusion process affect the structural and textural properties of calcium caseinate extrudates. With an increase in moisture content from 60% to 70%, there was a decrease in the cutting strength, hardness, and chewiness of the extrudate. Meanwhile, the fibrous degree increased considerably from 1.02 to 1.64. The hardness, springiness, and chewiness showed a downward trend with the rise in extrusion temperature from 50 °C to 90 °C, which contributed to the reduction in air bubbles in the extrudate. Screw speed showed a minor effect on fibrous structure and textural properties. A low temperature (30 °C) in all cooling die units led to damaged structure without mechanical anisotropy, which resulted from fast solidification. These results show that the fibrous structure and textural properties of calcium caseinate extrudates can be effectively manipulated by adjusting the moisture content, extrusion temperature, and cooling die unit temperature.

The development process of plant-based meat alternatives: raw material formulations and processing strategies

With the rapid growth of the world's population, the demand for meat is gradually increasing. The emergence and development of plant-based meat alternatives (PBMs) offer a good alternative to solve the environmental problems and disease problems caused by the over-consumption of meat products. Soybean is now the primary material for the production of PBMs due to its excellent gelation properties, potential from fibrous structure, balanced nutritional value, and relatively low price. Extrusion is the most widely used process for producing PBMs, and it has a remarkable effect on simulating the fibrous structure of real meat products. However, interactions related to phase transitions in protein molecules or fibrous structures during extrusion remain a challenge. Currently, PBMs do not meet people's demand for realistic meat in terms of texture, taste, and flavor. Therefore, the objectives of this review are to explore how to improve fiber structure formation in terms of raw material formulation and processing technology. Factors to improve the taste and texture of PBMs are summarized in terms of optimizing process parameters, changing the composition of raw materials, and enriching taste and flavor. It will provide a theoretical basis for the future development of PBMs.

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.

Soy Protein Hydrolysates Affect the Structural and Mechanical Properties of Soy Protein-Wheat Gluten Extrudates Using High Moisture Extrusion

This study aimed to investigate the effect of hydrolyzed soy protein isolate (HSPI) as a plasticizer in the soy protein mixture-wheat gluten (SP-WG) extrudates on its structural and mechanical properties during high moisture extrusion. Those SP were prepared by mixing soy protein isolate (SPI) and HSPI with different ratios. HSPI primarily consisted of small molecular weight peptides measured with size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The elastic modulus of SP-WG blends decreased with increased HSPI contents through the closed cavity rheometer. Adding HSPI at low concentrations (≤30 wt% of SP) enhanced a fibrous appearance and higher mechanical anisotropy while adding more HSPI resulted in a compact and brittle structure and tended to be isotropic. It can be concluded that the partial addition of HSPI as a plasticizer can promote the formation of a fibrous structure with enhanced mechanical anisotropy.

Meat hybrids-An assessment of sensorial aspects, consumer acceptance, and nutritional properties

So-called meat hybrids are a new class of products where a fraction of the meat product (e.g., 20%) is replaced with alternative protein sources, such as plant-based ones. Research suggests that these products could serve as a low-threshold offer for a specific target group that wants to cut down on meat, thereby facilitating the transition toward a more healthy and sustainable diet. Nonetheless, data demonstrate that meat hybrids with a high substantial meat substitution level often fail in the market. This study summarises findings on the physicochemical properties, sensory, and acceptance of six different meat hybrids (70% meat and 30% plant proteins) that were collected in the framework of a case study in the project AiF 196 EN. For this purpose, sensory characteristics were collected via two QDA sessions and a hedonic consumer test. Furthermore, the hybrid recipes were analysed in their proximate composition. The respective recipes varied in protein source (soybean, pumpkin, and pea) and mode of incorporation [textured vegetable protein (TVP), high moisture extrudate (HME)]. It was shown that a meat hybrid with a relatively high share of 30% plant-based proteins with peas as a protein source and TVP as a processing method can still attract consumers.

Hemp: A Sustainable Plant with High Industrial Value in Food Processing

In the era of SDGs, useful plants which provide valuable industrial outputs and at the same time pose less impact on the environment should be explored. Hemp seems one of the most relevant gluten-free crop plants to meet such requirements. Its high nutritional value is comparable to soy. Moreover, almost the whole body of the hemp plant has a wide array of utility: industrial production of food, fiber, and construction materials. In view of environmental sustainability, hemp requires less pesticides or water in cultivation compared to cotton, a representative fiber plant. This short review investigates hemp's sustainability as a plant as well as its utility value as a highly nutritional material in the food industry. Recent application research of hemp protein in food processing includes plant milk, emulsifiers, fortification of gluten-free bread, plant-based meat production, as well as membrane formation. These studies have revealed distinctive properties of hemp protein, especially in relation to disulfide (S-S)/sulfhydryl (-SH)-mediated interactions with protein from other sources. While its cultivation area and industrial use were limited for a while over confusion with marijuana, the market for industrial hemp is growing rapidly because it has been highly reevaluated in multiple areas of industry. Conclusively, with its sustainability as a plant as well as its distinctive useful property of the seed protein, hemp has promising value in the development of new foods.

The roles of growth factors and hormones in the regulation of muscle satellite cells for cultured meat production

Cultured meat is a potential sustainable food generated by the in vitro myogenesis of muscle satellite (stem) cells (MSCs). The self-renewal and differentiation properties of MSCs are of primary interest for cultured meat production. MSC proliferation and differentiation are influenced by a variety of growth factors such as insulin-like growth factors (IGF-1 and IGF-2), transforming growth factor beta (TGF-β), fibroblast growth factors (FGF-2 and FGF-21), platelet-derived growth factor (PDGF) and hepatocyte growth factor (HGF) and by hormones like insulin, testosterone, glucocorticoids, and thyroid hormones. In this review, we investigated the roles of growth factors and hormones during cultured meat production because these factors provide signals for MSC growth and structural stability. The aim of this article is to provide the important idea about different growth factors such as FGF (enhance the cell proliferation and differentiation), IGF-1 (increase the number of myoblasts), PDGF (myoblast proliferation), TGF-β1 (muscle repair) and hormones such as insulin (cell survival and growth), testosterone (muscle fiber size), dexamethasone (myoblast proliferation and differentiation), and thyroid hormones (amount and diameter of muscle fibers and determine the usual pattern of fiber distributions) as media components during myogenesis for cultured meat production.

Accumulation of Heterocyclic Amines and Advanced Glycation End Products in Various Processing Stages of Plant-Based Burgers by UHPLC-MS/MS

The accumulation of heterocyclic amines (HAs) and advanced glycation end products (AGEs) during different processing stages was investigated in commercial raw materials to plant-based hamburger meats (PBHMs). Principal component analysis (PCA) was performed to explore the difference between the samples of each processing stage. The total free HA level accumulated from 4.74-6.63 ng/g in raw plant proteins to 5.81-20.23 ng/g in textured vegetable proteins after extrusion. The concentration of MeAαC increased from 29.23 ± 3.50 to 59.44 ± 0.26 ng/g, resulting in an accumulation of the total protein-bound HAs after cooking at 160 °C for 6 min, but the MeAαC content decreased to 42.26 ± 0.11 ng/g when the heating duration was prolonged to 12 min. An evident accumulation of AGEs was observed during the thermal home-processing of PBHM. The total levels for all HAs were 381.30 and 160.30 ng/g in roast beef patty (RBP) and PBHM, respectively, with RBP having a better amino acid composition pattern. These results may reveal the target processing stage, which should be paid attention to for the inhibition of Maillard reaction derivative harmful products (MRDHPs) in plant-based meat products.

Influence of mild oxidation induced through DBD-plasma treatment on the structure and gelling properties of glycinin

The effects of dielectric-barrier discharge (DBD) plasma treatment (20 s to 120 s treatment time with 40 kV, 12 kHz) induced mild oxidation on the gelling properties, and related structural changes of glycinin were investigated. The gelling ability of glycinin was improved by the mild oxidation induced by the plasma treatment. Treated glycinin gels exhibited a continuous and uniform network microstructure. Samples treated for 120 s had a 2.07-, 3.99- and 2.03-fold increase in hardness, chewiness, and resilience compared to the 20 s treated samples. Structural analyses showed that primary and secondary structures of glycinin were unaffected. The tertiary structure was shifted, accompanied by a decrease in free sulfhydryl (-SH) content. At the same time, carbonyl content and average particle diameter were increased by DBD treatment. The DBD treatment facilitated the generation/exchange of intermolecular disulfide bonds and enhanced gelling properties of glycinin. It is concluded that controlled plasma-induced protein oxidation can improve protein functionality.