High moisture extrusion cooking of meat analogs: A review of mechanisms of protein texturization

Mulberry (Morus alba L.) leaf powder modified the processing of meat alternatives: Principal component analysis from apparent properties to chemical bonds

For texture control in plant-meat alternatives, the interrelationship between apparent characteristics and chemical bonds in high-fiber formulations remains unclear. The influence of mulberry leaf powder on apparent characteristics and chemical bonds of raw materials, block and strip products at addition amounts of 0.5-25% was analyzed. The results showed that 8% addition significantly increased the chewiness of the block by 98.12%. The strips' texture shows a downward trend, and the processing produced more redness and color difference. Additives promoted the formation of voids, lamellar and filamentous structures, and the strip produced more striped structures. Disulfide bonds significantly increased in the block, and the β-turn in the secondary structure enhanced by 12.20%. The β-turn transformed into a β-sheet in strips. Principal component analysis revealed that the texture improvement was associated with producing disulfide bonds and β-turn, providing a basis for high-fiber components to improve products' apparent characteristics by chemical bonds.

Maillard reaction products and metabolite profile of plant-based meat burgers compared with traditional meat burgers and cooking-induced alterations

We are undergoing a food transformation with the introduction of plant-based meat analogues, but little is known about their chemical characteristics. This study aimed to elucidate the Maillard reactions in plant-based meat burger alternatives (PBMBA). For this purpose, NMR-based metabolomics and targeted MS analysis of Maillard and dehydroalanine pathway markers were conducted on six PBMBA prototypes with different proportions of high-moisture protein extrudates, low-moisture extrudates and pea protein on a commercial PBMBA and on a meat burger before and after cooking. Results revealed that higher levels of Maillard reaction markers were present in PBMBAs in the uncooked state, with lower levels formed during cooking compared with conventional meat. The metabolite profile disclosed that the distinct pattern of the Maillard reaction could be attributed to different substrate availability, but data also revealed that pre-processing of the plant protein affects the presence of Maillard reaction products in PBMBAs.

Meat analogue preparation from cricket and rice powder mixtures with controlled textural and nutritional quality by freeze alignment technique

The rising demand for sustainable protein sources has encouraged interest in alternative food products like meat analogues. This study explores formulating meat analogues using cricket powder (CP) and rice flours, comparing them with soy protein-based analogues. CP exhibited a higher soluble protein content (5.9%) than soy protein powder (4.7%), enhancing textural properties by forming fiber-like structures, increasing firmness and adhesion, and reducing chewiness. Despite having a lower water holding capacity (WHC) than soy analogues, all samples outperformed chicken breast WHC. Under freezing conditions, CP and rice flour combinations formed multilayered structures in protein gels. The optimal formulations were CP and sticky rice flour (ratio 6:1) with respect to their texture properties, fiber structure, and nutritional value. This study highlights the potential of cricket powder and rice flour combinations as viable meat analogue ingredients, addressing the need for sustainable protein sources in the food industry.

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.

Near-infrared spectroscopy to quantify overall thermal process intensity during high-moisture extrusion of soy protein concentrate

High-moisture extrusion (HME) is widely used to produce meat analogues. During HME the plant-based materials experience thermal and mechanical stresses. It is complicated to separate their effects on the final products because these effects are interrelated. In this study we hypothesize that the intensity of the thermal treatment can explain a large part of the physicochemical changes that occur during extrusion. For this reason, near-infrared (NIR) spectroscopy was used as a novel method to quantify the thermal process intensity during HME. High-temperature shear cell (HTSC) processing was used to create a partial least squares (PLS) regression curve for processing temperature under controlled processing conditions (root mean standard error of cross-validation (RMSECV) = 4.00 °C, coefficient of determination of cross-validation (R2CV) = 0.97). This PLS regression model was then applied to HME extrudates produced at different screw speeds (200-1200 rpm) and barrel temperatures (100-160 °C) with two different screw profiles to calculate the equivalent shear cell temperature as a measure for thermal process intensity. This equivalent shear cell temperature reflects the effects of changes in local temperature conditions, residence time and thermal stresses. Furthermore, it can be related to the degree of texturization of the extrudates. This information can be used to gain new insights into the effect of various process parameters during HME on the thermal process intensity and extrudate quality.

Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products

BACKGROUND

High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins.

METHOD

Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5 g kg-1 was extruded at three different temperatures (115, 140, and 165 °C) using a co-rotating twin-screw extruder. The feed rate (85 g min-1), the moisture content (600 g kg-1), and the screw speed (300 rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index.

RESULTS

The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0 g kg-1.

DISCUSSION

In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products. © 2024 Society of Chemical Industry.

Microbial community structure of plant-based meat alternatives

A reduction in animal-based diets has driven market demand for alternative meat products, currently raising a new generation of plant-based meat alternatives (PBMAs). It remains unclear whether these substitutes are a short-lived trend or become established in the long term. Over the last few years, the trend of increasing sales and diversifying product range has continued, but publication activities in this field are currently limited mainly to market research and food technology topics. As their popularity increases, questions emerge about the safety and nutritional risks of these novel products. Even though all the examined products must be heated before consumption, consumers lack experience with this type of product and thus further research into product safety, is desirable. To consider these issues, we examined 32 PBMAs from Austrian supermarkets. Based on 16S rRNA gene amplicon sequencing, the majority of the products were dominated by lactic acid bacteria (either Leuconostoc or Latilactobacillus), and generally had low alpha diversity. Pseudomonadota (like Pseudomonas and Shewanella) dominated the other part of the products. In addition to LABs, a high diversity of different Bacillus, but also some Enterobacteriaceae and potentially pathogenic species were isolated with the culturing approach. We assume that especially the dominance of heterofermentative LABs has high relevance for the product stability and quality with the potential to increase shelf life of the products. The number of isolated Enterobacteriaceae and potential pathogens were low, but they still demonstrated that these products are suitable for their presence.

Enhancing the palatability of cultivated meat

Cultivated meat (CM) has transitioned from a futuristic concept to a present reality, with select products approved for consumption and sale in Singapore, Israel, and the USA. This evolution has emphasized scalable, cost-effective, and sustainable production, as well as navigation of regulatory pathways. As CM develops, a crucial challenge lies in delivering products that are highly appealing to consumers. Central to this will be refining CM palatability, a term encompassing food's taste, aroma, texture, tenderness, juiciness, and color. We explore the scientific and engineering approaches to producing palatable CM, including cell-line selection, cell differentiation, and post-processing techniques. This includes a discussion of the structural and compositional properties of meat that are intrinsically coupled to palatability.

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.

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.

Mechanochemical Degradation of Biopolymers

Mechanochemical treatment of various organic molecules is an emerging technology of green processes in biofuel, fine chemicals, or food production. Many biopolymers are involved in isolating, derivating, or modifying molecules of natural origin. Mechanochemistry provides a powerful tool to achieve these goals, but the unintentional modification of biopolymers by mechanochemical manipulation is not always obvious or even detectable. Although modeling molecular changes caused by mechanical stresses in cavitation and grinding processes is feasible in small model compounds, simulation of extrusion processes primarily relies on phenomenological approaches that allow only tool- and material-specific conclusions. The development of analytical and computational techniques allows for the inline and real-time control of parameters in various mechanochemical processes. Using artificial intelligence to analyze process parameters and product characteristics can significantly improve production optimization. We aim to review the processes and consequences of possible chemical, physicochemical, and structural changes.

Plant-Based Meat Proteins: Processing, Nutrition Composition, and Future Prospects

The growing need for plant-based meat alternatives promotes the rapid progress of the food industry. Processing methods employed in plant-based meat production are critical to preserving and enhancing their nutritional content and health benefits, directly impacting consumer acceptance. Unlike animal-based food processing, the efficiency of protein extraction and processing methods plays a crucial role in preserving and enriching the nutritional content and properties. To better understand the factors and mechanisms affecting nutrient composition during plant-based meat processing and identify key processing steps and control points, this work describes methods for extracting proteins from plants and processing techniques for plant-based products. We investigate the role of nutrients and changes in the nutrients during plant protein product processing. This article discusses current challenges and prospects.

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.

Evaluating the potential of millets as blend components with soy protein isolate in a high moisture extrusion system for improved texture, structure, and colour properties of meat analogues

This study explored the use of millets flours as a secondary ingredient with soy protein isolate (SPI) to develop fibrous high moisture meat analogue (HMMA). Three millets (sorghum, pearl millet, and finger millet) with three incorporation levels (10%, 20%, and 30%) were extruded at 60%, 65%, and 70% moisture content. The results showed that millet type, incorporation level, and moisture content significantly influenced the system parameters and textural properties. Good visual texturization was achieved at addition of pearl millet up to 30% incorporation level and sorghum and finger millet up to 20% incorporation level. Furthermore, the textural properties of HMMA made from SPI-millet blends were compared against HMMA made from SPI-gluten blend and real chicken. The HMMA made from SPI-millet flour had lower hardness, chewiness, resilience, springiness, tensile strength, cutting strength than that for SPI and SPI-wheat gluten blend and were much closer to corresponding values for real chicken. The results also showed that each of the three millet types generated distinctly different fibre patterns (thick to thin fibres) and colour (whiter to darker) of HMMA. Thus, HMMA produced from SPI-millet flour blends can offer a wide textural, fibre pattern and colour space for different plant-based meat applications. Since millets do not have gluten, they also offer an opportunity to make gluten-free HMMA's.

High moisture extrusion of plant proteins: advances, challenges, and opportunities

High moisture extrusion is a widely used technology for producing fibrous meat analogues in an efficient and scalable manner. Extrusion of soy, wheat gluten, and pea is well-documented and related products are already available in the market. There has been growing interest to diversify the protein sources used for meat analogues due to concerns over food waste, monocropping and allergenicity. Optimizing the extrusion process for plant proteins (e.g., hemp, mung bean, fava bean) tends to be time consuming and relies on the operators' intuition and experience to control the process well. Simulating the extrusion process has been challenging so far due to the diverse inputs and configurations involved during extrusion. This review details the mechanism for fibrous structure formation and provides an overview of the extrusion parameters used for texturizing a broad range of plant protein sources. Referring to these data reduces the resources needed for optimizing the extrusion process for novel proteins and may be useful for future extrusion modeling efforts. The review also highlights potential challenges and opportunities for extruding plant proteins, which may help to accelerate the development and commercialization of related products.

A review of green methods used in starch-polyphenol interactions: physicochemical and digestion aspects

The interactions of starch with lipids, proteins, and other major food components during food processing are inevitable. These interactions could result in the formation of V-type or non-V-type complexes of starch. The starch-lipid complexes have been intensively studied for over five decades, however, the complexes of starch and polyphenols are relatively less studied and are the subject of recent interest. The interactions of starch with polyphenols can affect the physicochemical properties and its digestibility. The literature has highlighted several green methods such as ultrasound, microwave, high pressure, extrusion, ball-milling, cold plasma etc., to assist interactions of starch with polyphenols. However, comprehensive information on green methods to induce starch-polyphenol interactions is still scarce. Therefore, in light of the importance and potential of starch-polyphenol complexes in developing functional foods with low digestion, this review has summarized the novel green methods employed in interactions of starch with flavonoids, phenolic acids and tannins. It has been speculated that flavonoids, phenolic acids, and tannins, among other types of polyphenols, may have anti-digestive activities and are also revealed for their interaction with starch to form either an inclusion or non-inclusion complex. Further information on the effects of these interactions on physicochemical parameters to understand the chemistry and structure of the complexes is also provided.

Non-animal-based options for animal-based foods- towards a systematic terminology

The market has seen a rapid increase in animal-free products intended to replace animal-based foods due to concerns for human health and environmental sustainability. However, there is a lack of consistent terminology for these products, with various terms being used interchangeably, creating ambiguity. To address this issue, we propose a systematic nomenclature that defines the most commonly used terms, namely alternative, substitute, replacement, and analog, along with examples of each. In this nomenclature, a substitute primarily serves a culinary purpose, while a replacement is concerned with nutritional properties. An analog strives to satisfy both culinary and nutritional attributes to closely mimic animal-based foods in terms of sensory, nutritional, and functional characteristics. The term "alternative" serves as an umbrella term encompassing all possibilities. This work aims to promote a clearer understanding of such products and their intended use and facilitate a unified use of terminology across disciplines. This will also enable informed decision-making for consumers and greater transparency in the food industry. The health and environmental implications of these products are not discussed in this perspective.

A global perspective on a new paradigm shift in bio-based meat alternatives for healthy diet

A meat analogue is a casserole in which the primary ingredient is something other than meat. It goes by various other names, such as meat substitute, fake meat, alternative meat, and imitation meat. Consumers growing interest in improving their diets and the future of the planet have contributed to the move towards meat substitutes. This change is due to the growing popularity of low-fat and low-calorie diets, the rise of flexitarians, the spread of animal diseases, the loss of natural resources, and the need to cut down on carbon emissions, which lead to greenhouse effects. Plant-based meat, cultured meat, algal protein-based meat, and insect-based meat substitutes are available on the market with qualities like appearance and flavor similar to those of traditional meat. Novel ingredients like mycoprotein and soybean leg haemoglobin are mixed in with the more traditional soy proteins, cereals, green peas, etc. Plant-based meat is currently more popular in the West, but the growing interest in this product in Asian markets indicates the industry in this region will expand rapidly in the near future. Future growth in the food sector can be anticipated from technologies like lab-grown meat and its equivalents that do not require livestock breeding. Insect-based products also hold great potential as a new source of protein for human consumption. However, product safety and quality should be considered along with other factors such as marketability and affordability.

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.

Hypotheses concerning structuring of extruded meat analogs

In this paper, we review the physicochemical phenomena occurring during the structuring processes in the manufacturing of plant-based meat analogs via high-moisture-extrusion (HME). After the initial discussion on the input materials, we discuss the hypotheses behind the physics of the functional tasks that can be defined for HME. For these hypotheses, we have taken a broader view than only the scientific literature on plant-based meat analogs but incorporated also literature from soft matter physics and patent literature. Many of these hypotheses remain to be proven. Hence, we hope that this overview will inspire researchers to fill the still-open knowledge gaps concerning the multiscale structure of meat analogs.

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.

Properties of Texturized Vegetable Proteins from Edible Mushrooms by Using Single-Screw Extruder

This research aimed to determine the feasibility of using mushrooms as an alternative ingredient in texturized vegetable protein (TVP) production using a single-screw extruder. TVPs from King Oyster (TVP-KO) and Pheonix mushroom (TVP-PH) were successfully developed and characterized. The visual appearance of TVP was reddish-brown, with a distinct roasted mushroom-soybean aroma. When rehydrated and cooked, both TVPs provided a minced meat-like appearance and chewy meat texture comparable to commercial TVP (TVP-Com); however, they had inferior water and oil holding and rehydration capacities. TVPs contained comparable protein content to TVP-Com (45–47 wt%), slightly lower carbohydrate content (33–36 wt% vs. 39 wt%), and ash (3–4 wt% vs. 8 wt%), but higher lipid content (7–8 wt% vs. 0.84 wt%) than TVP-Com. Sai-aua prepared from TVP-KO gained the highest overall acceptability. Mushrooms proved to be a potential source for TVP production due to their availability, low cost, nutritional value, and health benefits. Moreover, this finding helps add value to traditional meat products, which offer an opportunity for developing non-animal products with satisfactory sensory properties and low cost. In addition, the study would provide scientific resources for developing plant-based meat products that address health awareness and economic and environmental sustainability concerns.

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.