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

Abstract

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

Introduction

The perspective on devouring meat has changed over the generations; during our forefathers’ era, meat was the first choice of food without causing any problems. In fact, it was a staple food item in their daily lives. However, the shift towards healthier lifestyles began around the 1960s, prompting the search for alternative meat sources driven by health concerns, environmental considerations, and ethical issues related to animal slaughter.

Numerous environmentalists and researchers have proposed various ecological issues associated with meat production. For instance, a London-based independent policy institute, Chatham House, reported that animal agribusiness alone emits more greenhouse gases (GHGs) than does the entire transport system (Middleton and Littler, 2019). Thorough investigations of different life cycle assessment (LCA) studies conducted on different farm animals suggested that prefarm inputs (production and transportation of feed) and on-farm emissions were the major factors associated with GHG production (Biswas and Naude, 2016; Bohrer, (2019); Kalhor et al., 2016). One additional LCA study conducted in Japan indicated that beef produces more GHG (35.6 kg CO₂ eq/kg) than pork (6.9 kg CO₂ eq/kg) or chicken meat (6.1 kg CO₂ eq/kg) (Dente et al., 2018). Moreover, the production of meat exerts substantial pressure on finite arable land and freshwater reservoirs. Modern meat production techniques command approximately 40% of arable land and consume 56% of agricultural freshwater resources (Alexander et al., 2017). Eshel et al., (2019) have undertaken a noteworthy estimate, suggesting that replacing conventional meat in dietary regimens could conserve almost half of the national dietary land utilization, reduce nitrogen fertilizer application, and curtail GHG in the United States of America (USA).

The potential risk to public health is a significant concern linked with the consumption of traditional meat (Kumar et al., 2017). NCDs, including ischemic heart disease, chronic respiratory ailments, various forms of cancer, and type II diabetes, have been linked to suboptimal dietary habits, representing significant challenges to both sustainable development and overall human well-being (Chung et al., 2021; Kumar et al., 2017). The excessive consumption of red and processed meat contributes to 25% of all ischemic heart diseases, leading to more than 1.8 million fatalities each year (Papier et al., 2023). Epidemiological investigations consistently reveal a positive relationship between the intake of red and processed meats and a range of adverse health consequences, such as insulin resistance, non-alcoholic fatty liver disease, diverticular disease, and colon polyps (Papier et al., 2023; Zelber-Sagi et al., 2018). Furthermore, recent research highlights significant associations between processed meat consumption and heightened risks of breast, colorectal, colon, rectal, and lung cancers (Farvid et al., 2021). Several dietary and biological factors have been proposed to elucidate the relationship between meat consumption and health outcomes. These factors include the ingestion of saturated fatty acids, cholesterol, and heme iron; exposure to elevated cooking temperatures; and the presence of nitrates and nitrites in processed meat products. A comprehensive understanding of these elements is pivotal in discerning the health consequences associated with meat consumption (Alexander et al., 2017). Additionally, a notable number of foodborne illness cases are reported annually, primarily attributed to the ingestion of animal meats (including chicken, turkey, and beef) contaminated with pathogens such as Salmonella, Norovirus, and Shiga toxin-producing Escherichia coli (STEC) (Surveillance for Foodborne Disease Outbreaks Report, USA, 2017). Consequently, the ongoing debate regarding the optimal allocation of vital natural resources continues to flourish, with discussions revolving around the preference for meat production over the cultivation of essential staple grains (Kumar et al., 2017).

Other matters of concern associated with the consumption of meat involve ethical issues and religious beliefs. Ethical concerns prominently involve the treatment of animals in industrial meat production system, encompassing issues of animal suffering and rights. Similarly, various religions impose specific dietary laws and prohibitions regarding meat consumption, reflecting profound spiritual values and concerns about humane treatment. These ethical and religious considerations collectively underscore the increasing advocacy for exploring and adopting alternatives to conventional meat.

In this regard, numerous researchers have suggested that a shift from animal protein sources to more sustainable sources could halt the detrimental effects of meat consumption (Willett et al., 2019). A substantial portion of the population is becoming more interested in the circumstances related to meat consumption, consequently being readily open to the idea of substituting animal proteins in their diets with alternative and sustainable protein sources. This is evident from a study conducted in the Netherlands, where the percentage of flexitarians, or people who consume meat less frequently, rose from 13% in 2011 to 43% in 2019 (Dagevos, 2021).

According to research, shifting to a more vegetable-based diet could reduce greenhouse gas emissions by up to 50% (González-García, et al., 2018; Scarborough et al., 2014). Due to the ecological concerns associated with meat consumption, it has become increasingly important to shift toward a plant-based diet. This has paved the way for PBM products. In this comprehensive review, the focus is on elucidating the complexities surrounding the development of PBM, including technological hurdles and regulatory considerations. The review also explores promising solutions and innovations aimed at overcoming these challenges to meet the growing demand for sustainable and ethical meat alternatives.

Why plant-based meat analogs?

Meat analogs, a sustainable alternative to traditional meat, are products that can mock conventional meat products and have acquired a noteworthy place in the receptacle of protein-rich foods. Proteins extracted from nonanimal sources are precisely engineered through technology to replicate sensory attributes, including taste, color, and texture, as well as the nutritional characteristics inherent in conventional meat. These qualities serve as crucial standards in achieving a meat substitute that closely resembles its animal-derived counterpart (Kumar et al., 2017; Lacy-Nichols et al., 2021).

The practice of incorporating plant-derived proteins as meat substitutes has been around for several years but has recently gained significant attention. Historically, primary protein sources in meat alternatives have ranged from tofu (a soy product whose origins date back to 965 CE) to wheat protein (tracing back to 1301), followed by yuba (a soy-based product hailing from 1587), tempeh (a fermented soy product originating in 1815), and a blend of nuts, cereals, and legumes documented in 1895 (Shurtleff and Aoyagi, 2014).

PBM are manufactured from nonanimal proteins, particularly those of plant origin, and are manipulated in the form of whole food products to provide characteristic meaty flavors and textures (Kumar et al., 2017). The typical composition of PBM consists of water (50–80%), textured and nontextured proteins (14–45%), fat (0–15%), binding agents (1–5%), and minor ingredients such as natural colorants and spices (0–2%). The water in the meat analog forms the matrix to hold fibers and impart juiciness to the textured product (Cornet et al., 2021). Proteins (textured proteins and nontextured proteins), such as pea protein, soy protein, wheat gluten, and mixtures thereof, form an anisotropic fibrous structure. Fat and binding agents such as carrageenan, methylcellulose, and modified starches improve textural properties, including juiciness, tenderness, gelling strength, and thickening capacity. Natural colorants and spices are added to accurately mimic the sensory aspects of traditional meat (Kyriakopoulou et al, 2021).

Plant protein is either used as a complete or partial substitute for animal protein to formulate a vast range of food products, which can be broadly divided into two categories: emulsion-type and deep-fired. Emulsion-type meat analogs include sausages, Frankfurters, and salami, wherein water and fat bind together in an amphoteric protein network to form a plastic gel (Dreher et al., 2021; Stephan et al., 2018). Deep-fried products consist of nuggets, hamburgers, and burger patties (Saerens et al., 2021; Yuliarti et al., 2021). A survey conducted on the Australian population highlighted that plant-based burger patties were preferred over sausages as a meat substitute by consumers (Estell et al., 2021). This might be due to variations in the desired sensorial attributes and textural complications that occur during the structuring and networking of emulsion-type plant-based products. Henceforth, the tailoring of any meat analog involves the selection of appropriate ingredients because they exert a significant impact on the sensory and nutritional characteristics of the analog. There are numerous plant-based proteins that have been utilized as principal ingredients in the manufacturing of meat analogs, including soy protein, wheat protein, lentils, and many others. Some well-known plant proteins have been described in the Table 1

Table 1.

Health benefits and structuring properties of major plant plant sources

Protein Source	Key Nutritional Components	Health Benefits	Food Structuring Properties	Limitations	References
Soy Protein	Contains 36–56% protein;indispensable amino acids comparable to animal proteins (egg, milk, fish)	Antioxidant, antimicrobial, hypercholesterolemia, and anticancer effects due to ACE inhibitors, DPP-IV inhibitors, and BBI proteins	Good gelation and emulsification properties; forms fibrous structures similar to meat	Isoflavones may negatively impact male reproductive performance; genetically modified	Ashaolu, (2020), De Freitas et al., (2020),Oonincx and Finke, (2021), Wang et al., (2019),
Pea Protein	Contains 23–25% protein; high in essential amino acids (phenylalanine, leucine, arginine, isoleucine, lysine)	Antioxidant, antimicrobial, and antidiabetic effects through bioactive peptides	Good emulsification and water-binding properties; suitable for meat analogs	Deficient in thiol-containing amino acids (methionine and cysteine); gastrointestinal digestibility constraints; lacks cohesive network formation similar to gluten	Boukid et al., (2021), Çabuk et al., (2018), Godfray et al., (2018), Wang et al., (2022a)
Lentil Protein	Contains 21–31% protein; notable globulin, albumin, glutelin, and prolamins	Bioactive peptides with hypertensive effects; improved protein digestibility through cooking and enzymatic hydrolysis	Moderate gelation and emulsification; forms less fibrous structures compared to soy	Deficient in sulfur-containing amino acids; antinutritional factors (phytic acid, protease inhibitors, tannins, lectins); support less fibrous structure formation	Aryee and Boye, (2016), Joehnke et al., (2021), Vatansever et al., (2020), Wen et al., (2022)
Mung Bean Protein	Contains 25–28% protein; rich in essential amino acids (proline, glutamic acid, arginine, leucine, lysine, phenylalanine)	Antihypertensive effects through bioactive peptides	Forms gel-like structures; suitable for 3D-printed food items	Limited research on comprehensive fibrous structure formation; lacks extensive industrial application and standardization	Lee and Yoon, (2021), Sonklin et al., (2020), Wen et al., (2022)
Wheat Protein	Rich amino acid profile; viscoelastic properties, beneficial for food structure	Essential protein source for vegetarians and vegans; sustained energy and satiety	Excellent viscoelasticity due to gluten; forms strong, elastic doughs	Imbalance in essential amino acids, particularly lysine; lower PDCAAS value compared to soy protein; requires combination with other protein to improve structure	Bohrer, (2019), Ferrer et al., (2011), Mathai et al., (2017), Sharma et al., (2020)

Challenges confronting plant-based meat with their resolutions

The plant-based meat industry, despite its rapid growth and potential to address environmental and ethical concerns associated with conventional meat production, faces several significant challenges. Despite anticipations of rapid growth and widespread adoption of alternative meat options, prevailing sentiment suggests these products are more likely to serve as complementary additions rather than complete replacements for traditional animal-based meats in meeting the escalating demand for protein (Newton and Blaustein-Rejto, 2021). Both non-users and consumers of meat substitutes concur that the optimal meat alternative should be economically competitive with traditional meat options while boasting elevated levels of protein, vitamins, and lower calorie content. A multitude of obstacles impede the widespread adoption of PBM, encompassing factors such as lack of familiarity, sensory appeal, taste, nutritional value, affordability, and convenience, collectively deterring individuals from embracing plant based diet (Bryant, 2019). Addressing these issues necessitates continuous innovation in food technology and ingredient formulation to enhance the nutritional profile and sensory qualities of PBM at economical level, thereby meeting consumer expectations and increasing their acceptance. Below, the discussion encompasses key challenges encountered in the development of PBM, alongside potential solutions.

Nutritional equivalence

Human understanding of nutrition has evolved to combat diseases that affect human health. Nutrients, both macro- and micronutrients, play distinct roles in the human body, contributing to various physiological functions and processes (Nieder et al., 2018). Literature suggests that conventional meat is an energy-dense food rich in high-quality protein, featuring a well-balanced sequence of essential amino acids that are easily digestible. Moreover, the fat content in meat is predominantly rich in saturated fatty acids (Pereira and Vicente, 2013; Wyness, 2016), which have been associated with increased health risks such as cardiovascular disease, type 2 diabetes, and obesity (Bendinelli et al., 2013; Rouhani et al., 2014).

In contrast, next-generation PBM products offer a potentially healthier dietary choice, providing 58% less energy, 96% less saturated fat, and no cholesterol compared to traditional meat (Lacy-Nichols et al., 2021). PBM also contains significant amounts of dietary fiber (Fig. 1), which not only contributes to health benefits but also enhances textural qualities in the product. Dietary fiber improves product juiciness by disrupting the protein phase, thereby helping to retain more moisture (Diaz et al., 2022).

Fig. 1.

Macronutritional profile of conventional and plant-based meat analogs

Despite its favorable nutritional profile, one of the major challenges faced by PBM is its relatively low in vitro protein digestibility (75–80%) compared to pork and beef (90–95%). This distinction is further highlighted by the greater quantity of small molecular peptides detected in pork and beef than in PBM during gastrointestinal digestion (Xie et al., 2022; Zhou et al., 2021). The decreased protein digestibility in PBM is attributed to the presence of antinutritional factors such as phytates, tannins, trypsin inhibitors, and lectins, as well as reduced enzyme accessibility due to rigid cell walls and seed coats (Sá et al., 2020). Another challenge with using legumes as functional ingredients is the presence of substances that promote gastrointestinal discomfort, such as raffinose. Due to the absence of α-galactosidase in the human gut, this sugar cannot be hydrolyzed and absorbed by humans (Bennetau-Pelissero, 2019).

These challenges can be addressed by selecting appropriate pre-processing treatments, such as enzymatic hydrolysis, cooking, sprouting, fermentation, sonication, microwave processing, high-pressure processing, electric field treatment, and ohmic heating. Optimizing these process parameters is crucial to achieving meat analogs with optimal bioavailability, digestibility, and functional qualities (Shaghaghian et al., 2022). For instance, fermentation as a pre-treatment can effectively reduce phytic acid content and protease activity in plant proteins, thereby improving the protein digestibility of PBM. However, it is essential to optimize the fermentation conditions and select appropriate starter cultures, as over-fermentation may negatively impact sensory attributes due to the degradation of macromolecules, resulting in a slimy and softer texture and the generation of off-flavors (Clark et al., 2022; Elhalis et al., 2023; Kaleda et al., 2020). Moreover, some plant proteins are considered inferior to animal proteins due to their deficiency in essential amino acids. This diminished anabolic effect of PBM may be mitigated through strategies such as enhancing its amino acid composition by fortifying it with essential amino acids or by amalgamating diverse plant protein sources (Berrazaga et al., 2019).

In the context of micronutrients, meat is considered an excellent source of iron and vitamin B12, as well as other B-complex vitamins and minerals such as zinc, selenium, phosphorus, and niacin. To achieve nutritional equality with conventional meat, the PBM needs to be supplemented with micronutrients. Plant derivatives are devoid of vitamin B complexes, particularly vitamin B12, and the available iron binds with phytic acid (an antinutritional factor), restricting gut absorption. The supplementation approach can be implemented either by adding micronutrients directly or by adding micronutrient-rich foods to meat analogs. To address this, researchers have explored various strategies to enhanced nutrient profile of PBM which are enlisted in Table 2.

Table 2.

Technologies applied to enhanced nutritional content of plant-based meat analogs

S.No	Technology	Benefits	Limitations	References
1	Nanoemulsions	Improved bioavailability and stability of lipophilic vitamins (e.g., vitamin D), omega-3 fatty acids, and antioxidants in plant-based meat analogs	Nanoemulsion stability, potential oxidation during processing, bioavailability in the body	Marcillo-Parra et al., (2021)
2	Enzymatic hydrolysis and encapsulation techniques	Bioactive peptides and antioxidants were incorporated in lentil protein-based meat analogs	Enzyme specificity, peptide stability, gastrointestinal absorption efficiency	Zhang et al., (2022b)
3	Encapsulation technique	Increased iron content and improved nutritional profile of pea protein-based analogs	Iron bioavailability, potential interactions with other food components, consumer acceptance	Estrada et al., (2018)
4	Incorporation of novel ingredients	Wolffia globosa-mankai, a marine plant was incoprporated to increase the vitamin B12 content in plant-based meat analogs	Vitamin B12 stability, absorption efficiency, scalability of sourcing	Sela et al., (2020)
5	Nanotechnology	Soy protein fibrils containing iron nanoparticles were produces to improve nutritional properties through iron fortification	Nanoparticle dispersion, structural integrity of fibrils, long-term health implications	Xiang et al., (2021)
6	Fermentation	Increased Vitamin B12 content due to co-inoculation with Propionibacterium freudenreichii, a food-grade, vitamin B12 producing bacterium in lupin temph, texture and volatile compounds were not affected	Scalability of product, consumer acceptance, absorption efficiency	Wolkers–Rooijackers et al., (2018)
7	Microencapsulation technology	Incorporation of microcapsules of anthocyanins to improved the antioxidant capacity and hue of plant based meat analog	Stability of anthocyanins during storage and microparticles dispersion, interactions with other food components	Szpicer et al., (2022)

Advancement in technology helps in filling the nutrtional gap and sensory attributes between PBM and consumer acceptability. However, more detailed research is needed to understand the fate of these fortified nutrients in the human gut. It is crucial to investigate the bioavailability, absorption efficiency, and potential interactions of these nutrients within the gastrointestinal tract. Furthermore, long-term clinical studies are essential to ensure that these fortified nutrients do not generate harmful compounds, such as oxidation products, and that they provide the intended health benefits without adverse effects. Understanding these aspects will be key to optimizing the fortification strategies and ensuring the safety and efficacy of nutrient-enriched PBM products.

Techno-functional properties

Plant proteins are increasingly being recognized as highly versatile alternatives to conventional meat proteins because of their unique functional properties rather than solely their nutritional content. Although nutritional value remains an essential consideration in the development of PBM, the techno-functional properties of plant proteins are equally crucial in determining their intended use within the food industry. These functional properties encompass a broad range of attributes such as solubility, gelling, emulsification, foaming, fiber formation, curdling, flavor binding, and thermal stability that make them indispensable in various food applications (Rathnakumar et al., 2023). Each of these characteristics plays a distinct role in shaping the texture, structure, and sensory attributes of meat analogs. For instance, the fat and water absorption properties of plant proteins are exploited to entrap and evenly distribute fats and water in products such as sausages and meat analogs, enhancing their mouthfeel and juiciness. Emulsifying materials are harnessed to create and maintain stable emulsions in sausages, dressings, and plant-based spreads. Foaming properties, on the other hand, are instrumental in forming stable foam structures in meat analogs and desserts, providing the desired texture and mouthfeel. The ability to form stable gels is central to the creation and maintenance of protein matrices in foods such as plant-based meats, curds, and cheese alternatives, ensuring the desired texture and structural integrity (Arteaga et al., 2020).

The functional properties of plant proteins are modulated by various factors, including their molecular size, conformational structure, charge distribution, and any structural changes that may occur during food processing (Bessada et al., 2019). These factors impact how plant proteins behave in various food applications and are essential considerations when formulating plant-based products, as depicted in Fig. 2. Understanding these factors allows food scientists and manufacturers to optimize the functionality of plant proteins in their products, ultimately enhancing the quality and consumer appeal of plant-based alternatives across the food industry.

Fig. 2.

Factors influencing the techno-functional and organoleptic properties of meat analogs

Solubility

Solubility not only serves as a practical gauge for assessing protein functionality but also has a significant impact on various other functional attributes (emulsifying capacity, water holding capacity, and foaming capacity). Several factors impact the solubility of plant proteins, including the isolation pH, temperature, ionic strength, and surface hydrophobicity. Generally, the relationship between pH and protein solubility exhibits a U-shaped pattern, with peak solubility observed at pH values on either side of the protein’s isoelectric point (pI) and the lowest solubility occurring at the pI. Notably, pea protein isolate demonstrates its highest solubility at pH 12.0 compared to acidic pH levels. Furthermore, an increase in temperature has been observed to increase protein solubility, particularly at alkaline pH values (Sajib et al., 2023). In the case of soy protein, a comparable solubility pattern is evident, with the highest solubility achieved on either side of its isoelectric point (pI ≈ 4.6) (O’Flynn et al., 2021). In contrast, wheat gluten exhibits enhanced solubility in acidic environments (pH 2–5), rendering it particularly suitable for use in acidic food applications (Zhao et al., 2020).

Protein solubility in an aqueous medium is predominantly governed by disulfide bonding and noncovalent interactions, which contribute to the formation of secondary and tertiary protein structures. These interactions not only impart rigidity but also facilitate the development of a fibrous texture in meat analog extrudates (Lee et al., 2022). To achieve distinct fibrous meat analogs, proteins should ideally possess relatively good solubility. However, studies eluicadted that high protein solubility can indeed be disadvantageous for anisotropic structure formation, and that it is more favourable to target optimum protein solubility (Geerts et al. 2018; Nisov et al; 2022). Thus, it can be inferred that solubility is not considered an overriding factor when selecting ingredients for the formulation of PBM.

Gelling capacity

In the realm of contemporary food science, plant proteins have gained extensive use in the replication of animal-derived proteins. This utilization is attributed to their remarkable ability to form gels, which is instrumental in creating fibrous matrices that impart a texture reminiscent of that of meat. This is particularly significant in the context of sausage-based analogs. The formation of a delicate gel is a prerequisite prior to heating, and the gel subsequently strengthens as proteins denature and aggregate.

Pea protein has emerged as a prominent choice in the production of meat substitutes, including sausages and burger patties, either as a complete replacement for meat or as a partial substitute. Its suitability lies in its capacity to form moderately elastic gels through interactions with fat and water constituents (Broucke et al., 2022; Shen et al., 2022). However, it is important to acknowledge that developing robust gel structures with pea proteins presents challenges, primarily due to their considerably lower gelling capacity than that of soy proteins. Furthermore, heat-induced gels formed by soy protein isolate exhibit greater strength than their counterparts created with pea protein isolate (Hadi and Brightwell, 2021; Rubio et al., 2020). To enhance the functionality of pea proteins, innovative techniques such as ultrasonication, microfluidization, homogenization, and pH-shifting treatment are being explored. These methods not only improve the gel-forming capabilities of pea proteins but also contribute to the enhancement of their nutritional quality (Jiang et al., 2017; Wang et al., 2020; Zhao et al., 2022a).

Emulsifying capacity

The emulsifying capacity of a protein refers to its ability to create and maintain stable emulsions. The notable emulsifying capacity of plant proteins plays a crucial role in stabilizing the structure of meat analogs especially emulsion type sausages. This is achieved by binding with both the hydrophobic and hydrophilic phases in the highly hydrated protein matrix, thereby retaining the flavor and moisture in the sausages. Variations in emulsification capability among proteins can be attributed to differences in their albumin-to-globulin ratio (Karaca et al., 2011). Notably, a higher globulin content tends to correlate with an increased emulsifying capacity. Comparative investigations of the functional attributes of commonly used pulse proteins, such as pea, chickpea, lentil, and soy, have indicated that lentil protein isolate possesses the highest surface charge and is capable of forming stable emulsions with small droplet sizes, akin to soy protein isolate. The emulsification properties of plant proteins can be improved by physical, chemical, and bio-enzymatic methods. For instance, combining pH-shifting with ultrasound and heating had improve the emulsifying capacity of pea protein isolates and reduced the droplet size of emulsion (Zhao. et al., 2022b).

Water and fat holding capacity

The water and fat absorption capacity quantifies the amount of water or fat that can be absorbed per gram of protein material (Branch and Maria, 2017). These absorption capacities are influenced by the availability of polar and nonpolar amino acids within the protein structure. Notably, mung bean protein exhibits water- and fat-binding capacities comparable to those of soy protein (Du et al., 2018). One potential explanation for the elevated water-binding capacity of mung bean protein could be its abundance of phosphate groups and other polar entities, which enhance protein hydration (Du et al., 2018).

Water and fat holding capacities are major factors governing the juiciness, which is of paramount interest in plant-based meat (PBM). According to the Flory–Rehner theory, water and fat holding capacities relate to the affinity to form crosslinks between polymers and hydrophilic or hydrophobic mediums (Cornet et al., 2021). Protein crosslinks can be modified using physical, chemical, or enzymatic treatments. Enzymes such as transglutaminase and laccase are used to modify protein crosslinks in PBM patties, ultimately affecting water and fat holding capacities. Chemical treatments include the addition of methylcellulose and sugar beet pectin to impart a strong network that can retain moisture (Sakai et al., 2021). Physical methods, such as toasting, have been shown to increase the water holding capacity of soy proteins while decreasing solubility, which complements fibrous structure formation (Geerts et al., 2018; Nisov et al., 2022).

Foaming capacity

Foaming capacity is a crucial functional attribute that facilitates the emulation of both the structural framework and texture characteristic of authentic meat within meat analogs. This property is essential for developing a meat analog that exhibits porosity, tenderness, and succulence, thereby closely approximating the sensory attributes of conventional meat. Typically, increased porosity in the meat analog correlates with higher water retention after hydration (Lee et al., 2022). Proteins play a vital role in foam stabilization by adsorbing at the air/water interface, thereby increasing the viscosity of the medium and reducing surface tension to entrap air bubbles (Cermeño et al., 2024), enhancing the structure’s porosity.

The porous structure of plant-based meat can be augmented by selecting proteins with high foaming capacity. Notably, the foaming capacity of mung bean protein is lower than that of pea protein isolates (Du et al., 2018). Conversely, lentil protein demonstrates an impressive foaming capacity, reaching 680%. This remarkable capacity positions lentil protein competitively alongside well-recognized standard proteins such as eggs (with foaming capacities ranging from 176 to 600%) and whey (with foaming capacities ranging from 500 to 800%) (Jarpa-Parra et al., 2014). Methods to enhance the foaming capacity of proteins include pre-treatments such as pH shifting, ultrasonication, and heat treatment (Wang et al., 2020; Zhao et al., 2020).

Organoleptic properties

Emulating the precise sensory properties of conventional meat poses a formidable challenge in the realm of plant-based alternatives. Research by Broucke et al. (2022) underscores that substituting animal protein with plant-derived counterparts often results in products that are comparatively less flavorful, with a softer texture, prominent cavities, and a less robust fibrous structure (Broucke et al., 2022). Overcoming these hurdles hinges on the meticulous selection of ingredients that synergize effectively and the strategic application of advanced techniques.

Color

Fresh meat color is regarded as one of the primary indicators that determines meat quality, freshness, price, and consumer purchasing decisions. In conventional meat, myoglobin (Mb) is one of the principal ingredients responsible for the color and flavor of the meat. The amount and proportion of three forms of myoglobin, deoxy-myoglobin (DeoMb), oxy-myoglobin (OxyMb), and metdeoxy-myoglobin (MetMb), define the meat color and are formed as end products of different spontaneous reactions that occur between myoglobin and oxygen (Gao et al., 2014). Furthermore, during the cooking process, a variety of compounds known as melanoidins are generated as the final outcome of the Maillard reaction, and they play a pivotal role in determining the color and flavor of cooked meat (Arihara et al., 2021). However, replicating the exact meat color in the case of plant-based meat presents a significant challenge. This challenge necessitates the careful selection of suitable colourants, which can be either artificial or natural (such as fruit or vegetable extracts, leg hemoglobin, or synthetic colors). Some commercially available PBM (beyond meat) contains pulverized beet root to mimic the color change when raw meat is cooked (Beyond Burger, Official Site). Similarly, the incorporation of reducing sugars such as xylose, dextrose, and maltose could serve as an important agent for developing color in PBM via a nonenzymatic browning reaction (Kyriakopoulou et al., 2021).

Flavor

Meaty flavor is an amalgamation of various volatile compounds that are the result of various phenomena that occur during the cooking of meat, of which the Maillard reaction and lipid oxidation are significant. The chemical reaction between the products of the aforementioned reaction is the source of many volatile compounds responsible for producing meaty flavors in meat. A diverse array of unique meat flavor compounds can be generated, predominantly featuring heterocyclic compounds with more than one nitrogen or thiol atom as well as long chains of saturated carbon atoms containing more than four carbon atoms. Some noteworthy examples of these volatile groups include pyridine, pyrazine, thiophene, thiazole, and oxazole, all of which possess saturated side chains of carbon (Diez-Simon et al., 2019). Interestingly, thiophene compounds are at the center of this interplay, with 2-pentylthiophene, 2-hexylthiophene, and various mercaptans, such as 2-thiophene mercaptan, 2-furan methyl mercaptan, and 2-methyl-3-furan mercaptan, being the most prominent (Sun et al., 2022).

Plant protein has inherited earthy, beany, and greasy aromas and tastes that need to be masked to emulate the taste of traditional meat. For instance, the beany flavor of pea protein isolates is due to the accumulation of aldehydes and ketones as a result of lipid oxidation or free radical generation. The beany flavor can be reduced by extracting the protein under modifying conditions such as alkaline conditions (pH 9; solid dispersion-based spray-drying) (Gao et al., 2014; Lan et al., 2019). In accordance with a study undertaken by Sonklin et al., (2018), the umami flavor of mung bean protein can be enhanced through hydrolysis using bromoelain enzyme, subsequently imparting a meaty aroma and taste.To produce PBM with a rich meaty flavor, various additives can be used during processing, such as protein hydrolysate, amino acids, hexose or pentose sugars, monosodium glutamate, polyphosphates, sodium caseinate, and ferrous chlorophyllin (Chen, et al., 2022; Dermiki et al., 2013; Kumar et al., 2012).

The use of protein hydrolysate via the Maillard reaction is an effective method for producing flavor compounds. The starch-producing industry generates gluten as a byproduct, and it possesses considerable nutritional value due to its high cysteine content (2–2.5%), surpassing that of other plant proteins such as soy protein (∼1.7%), as reported by Sun et al., (2023). Cysteine, an amino acid containing sulfur, participates in the formation of distinct Amadori rearrangement products when combined with free sugars at the initial phase of the Maillard reaction (Fig. 3). These products subsequently breakdown into sulfur-containing and heterocyclic compounds, ultimately contributing to the development of a savory meaty aroma (Gao et al., 2020).

Fig. 3.

Generation of meaty flavor compounds from cysteine

Texture

The texture of meat is a prime sensory parameter that reflects the quality of the meat and is an amalgamation of different characteristics, such as hardness, springiness, chewiness, juiciness, and even greasiness. Emulating the structure of myofilaments, a type of tissue found in conventional meat that is responsible for tenderness and juiciness, is practically impossible. The texture of conventional meat is an intricate yet essential factor that is determined by many different elements, such as the composition of ingredients, aging, and rigor mortis (Burger and Zhang, 2019).

The most significant milestone to attain in the formulation of a meat analog is the development of a fibrous textural structure. During the formation of a fibrous structure, a decrease in intramolecular forces leads to the unfolding of the molecular structure of the protein, resulting in increased flexibility. Moreover, the strengthening of hydrogen bond linkages facilitates the rearrangement of the protein structure, which aids in forming a fibrous structure (Zhang et al., 2022a). To achieve this anisotropic structure, it is essential to tailor processing conditions, equipment, and select appropriate techniques. Various methods have been employed to create an anisotropic texture in plant proteins that closely resembles authentic meat. For instance, Dekkers et al. (2018) differentiated these techniques based on their operational concept, categorizing them into either a bottom-up strategy or a top-down strategy to form fibrous structures. Specifically, a bottom-up strategy is characterized by initially generating structural elements and subsequently assembling them into larger products with the aid of linking or binding agents, such as egg white and gluten. On the other hand, a top-down strategy mimics the textural characteristics of meat by employing mechanical force in larger parts only. Thus, understanding and applying these strategies are crucial for the successful development of meat analogs with desirable fibrous textures. By employing different techniques, it becomes possible to prepare thousands of novel meat analog products. Some of these plant-based meat analog products and their corresponding structural techniques are represented in Table 3.

Table 3.

Plant-based meat analogs and their structural techniques

S.No	Meat Analog	Type and amount of Protein	Technique	Type of Equipment	Comments	References
1	Textrurised Vegetable Protein (TVP)	Soy Protein, Wheat Gluten and Green Tea Extract	Extrusion	Twin Screw Extruder	Higher green tea extract in TVP resulted in more direction structure, high antioxidant content, darker color, better texturization and lower expansion	Ma and Ryu, (2019)
2	Meat analog Powder	Protein isolates of mung bean, pea, peanut and soy	Extrusion	Twin- Screw Extruder	Isolates of soy protein and pea protein showed more water holding capacity and sponge like texture as compare to other protein. Isolates of mung bean and isolates of peanut showed low hydration and poor textural properties	Samard et al., 2019)
3	Texturized vegetable protein (TVP) powder	Protein isolates of soy protein and wheat gluten 40:60	Extrusion	Twin screw extruder	TVP powder have similar texture characteristics as like chicken. Color of TVP powder is different from original meat powder due to the presence of different amino acid sequence	Samard et al., 2019)
4	Vegetable meat analog	Protein isolates of pea and soy and wheat gluten	Shear Technology	High-temperature conical shear cell	Soy protein and gluten blend have much broader temperature range as compare to blend of pea protein and gluten. At higher temperate pea isolate and gluten blend show less fibrous, brittle and layered structure	Schreuders et al., 2021)
5	Extruded meat analog	Soy protein and gluten	High moisture extrusion	Pilot scale corotating twin screw extruder	Increased amount of gluten results in more fibrous structure of meat analog. Hydrogen bonds and disulfide bonds play pivotal roles in stabilizing and forming the fibrous structure	Chiang et al., (2021)
6	Plant based Nugget	Pea Protein and Wheat Protein (3:1)	Freeze Structuring	Freezer	Plant based nugget formulated had similar texture as a commercial product	Yuliarti et al., (2021)
7	Steaks	Textured soybean protein and Xanthan gum	3D printing	3D printing Extrusion	The manipulation of process parameters, such as infilling-to-filling ratio and the pattern of infilling, exerted a notable influence on the texture characteristics of the sample	Chen et al., (2021)
8	Sausage	Mushroom and soybean protein isolate	Thermoextrusion	Single lead extruder	The analysis showed that sausage prepared from 15% mushroom and soybean protein isolate with 35%water have closer texture resemblance to beef	Yuan et al., (2021)
9	Colored Meat Analog	Mung Bean Protein isolate, Beet Root, Xylose, Methylcellulose	3D printing	3D printing Extrusion	Xylose had textural modifying properties in protein rich gels like meat analog. It significantly increases the hardness and shear modulus of developed product	Wen et al., (2022)
10	Chicken nugget	Pea protein isolate, starch, soy lecithin	3D printing	3D printing Extrusion	Process parameters like size of nozzle and smoothness of printing paste had a pivotal role in 3D printing process, which need to be standardized according to the product and raw material	Wang et al., (2022a, b, c)
11	Imitation of muscle fibers	Sodium alginate powder, soybean protein isolate	Wet Spinning	Spinneret	Producing fibers with high protein content or under alkaline pH conditions encourages the formation of a porous structure and improves their ability to retain water	Cui et al., (2022)
12	Chicken Analogs	Potato Protein and gella gum	Shearing	-	A novel low-energy method, utilizing principles of soft matter physics, involves subjecting coacervate solutions to shear forces to create fiber-like structures. These structures are then thermally stabilized through protein gelation	Ryu et al., (2023)
13	Meat Analog	Soy Protein Isolate Powder, xanthan gum/ carrageenan/ pectin)	Fiber Spinning	-	Anionic fibers, such as xanthan gum and carrageenan, generate more fibrous structures compared to anionic branched polysaccharides. The inclusion of glycerol aids in retaining moisture throughout the process	Joshi et al., (2023)

Extrusion, a commonly employed method, transforms and restructures plant proteins into fibrous forms through thermomechanical forces such as shearing and compression. The extrusion process can be broadly characterized into low moisture extrusion (LME) and high moisture extrusion (HME) (Peng et al., 2023). HME, which includes a cooling die, produces meat analogs with dense structures and chewy textures similar to traditional meat. Freeze structuring, another innovative technique, involves freezing an aqueous protein solution or slurry, followed by the elimination of ice crystals to obtain a fibrous structure similar to traditional meat (Chantanuson et al., 2022). Shear cell technology and electro-spinning are other methods used to create fibrous structures, although they come with challenges such as high energy requirements and equipment costs (Cornet et al., 2022; Mattice & Marangoni, 2020).

In addition to these methods, the three-dimensional (3D) printing process is gaining prominence for producing intricate and anisotropic muscle structures using plant proteins. Researchers have formulated 3D plant-based meat analogs using pea protein and soy protein (Ko et al., 2021; Wang et al., 2022a). However, these analogs often face challenges, such as disintegration during cooking due to inadequate fibrous network formation (Shahbazi et al., 2021). The use of structural-modifying compounds, such as thickeners and gelling agents, may improve the fidelity and integrity of 3D-printed products (Dick et al., 2021). Despite the advancements in these techniques, significant challenges remain, such as high energy requirements and the substantial cost of equipment installation. Further research and development are needed to make these methods more sustainable and cost-effective, thereby improving the sensory and nutritional attributes of plant-based meat analogs to meet consumer expectations.

Apart from selecting a suitable technique to form fibrous structures, the appropriate selection of ingredients and their suitable concentration to form the anisotropic structure of imitated meat is a very arduous task. Each ingredient has a specific role in the development of the intricate structure of PBM. Wheat gluten is a popular component frequently used as a secondary ingredient in the production of meat substitutes because of its potential to create a meat-like, anisotropic structure. Some researchers have highlighted that the disulfide hydrogen (H–S–S–H) bond present in wheat gluten governs the formation of the anisotropic structure of the meat analog via protein crosslinking (Godfray et al., 2018). Water acts as a plasticizer and is required to impart the desired juiciness to the product (Majzoobi et al., 2017). Moreover, the inclusion of hydrocolloids has a promising function in modifying the rheological properties of meat analogs. Hydrocolloids, categorized as water-soluble polysaccharides, enhance textural properties by functioning as agents that facilitate the connection of protein filaments. They also act as extenders, improve chewiness, retain water, and increase bulk density. Some common examples previously applied to modify the texture of meat analogs are cellulose, carrageenan, methylcellulose, pectin, kappa-carrageen, konjac mannan, carrageenan, guar gum, xanthan, and locust bean gum (Majzoobi et al., 2017; Palanisamy et al., 2018).

Consumer acceptance

A meat analog has been suggested and offered solutions to a variety of problems related to animal welfare, health hazards, and ecological threats, as proposed by the proponents of these products (Pereira and Vicente 2013). According to several consumer reviews, modern meat analogs meet consumer expectations in terms of their sensory characteristics, particularly their texture and taste, which resemble those of conventional meat. Certain ethical groups and environmentally conscious consumers are willing to pay a premium price to acquire these meat substitutes (Michel et al., 2021; Pérez et al., 2023). A survey conducted among older adults in Europe reported that PBM had a 58% acceptance rate compared to in vitro meat-based protein, with only 6% acceptance (Grasso et al., 2019).

Currently, PBM has mainly targeted vegetarians and vegans. Meat analogs from plants have expanded their target market to include meat eaters and flexitarians as awareness of the sustainability and health impacts of meat consumption has increased (Kołodziejczak et al., 2021). Consumers are most likely to accept plant-based meat analogs when they are concerned about environmental issues, ethical concerns, and health risks related to the consumption of high amounts of meat and meat products (Hartmann et al., 2021). A study conducted in India on the Gen Z population (15–25 years) revealed that environmental concerns and food safety, as well as increasing concerns about zoonotic diseases such as COVID-19, are driving consumers to choose PBM (Dhawan and Choo, 2021). Conversely, a recent study that assessed the reception of meat substitutes in comparison to other protein-rich sources found that participants did not perceive meat substitutes as being inherently healthier or more sustainably produced than traditional protein-rich foods. They perceive meat substitutes as less natural and more processed (Hartmann et al., 2021; Varela et al., 2022). The incongruity of plant-based meat could be attributed to the highly processed and ultra-processed nature of some meat alternatives. Furthermore, there is a lack of scientific evidence to substantiate the assertion that these products contribute to a healthy diet both in the short term and in the long term (Tso et al., 2020; Pereira and Vicente, 2013).

Different demographic studies have assessed consumer behavior and perceptions toward meat analogs. The factors affecting the food buying behavior of consumers are depicted in Fig. 4. Most studies have reported that consumer food neophobia, lack of scientific evidence to elicit nutritional consequences of these PBMs and fondness for traditional meat restrict them from adopting plant-based meat. Therefore, manufacturers and proponents of PBM should work on generating awareness among consumers regarding the environmental impact of meat and should explore new methods to motivate consumers to decrease meat consumption (Hartmann et al., 2021). Furthermore, the artificial meat industry should diversify its marketing channels to enhance the accessibility of artificial meat products. This can be achieved through initiatives such as educational lectures and media promotions (Shen and Chen, 2020).

Fig. 4.

Factors governing consumer perceptions of the consumption of meat analogs

Industrial challenges

The process of producing PBM at industrial scale commence with the selection of premium, high-protein plant sources. These ingredients are meticulously chosen for their capacity to emulate the texture and nutritional profile of conventional meat. The initial phase involves the extraction and isolation of plant proteins, which is subsequently followed by a texturization process designed to achieve a meat-like consistency. (Kyriakopoulou et al., 2021). This intricate process necessitates advanced technological interventions and expertise.

Food industries engaged in the development of PBM face several significant challenges. These include high production costs, limited large-scale production capabilities, and non-remunerative processes. These obstacles arise from the complex and resource-intensive task of replicating the texture, flavor, and nutritional profile of traditional meat using plant-based ingredients. High production costs are driven by the necessity for specialized equipment, high-quality raw materials, and advanced processing techniques. Moreover, reliance on small-scale production, limits economies of scale and further drives up costs.

The implementation of innovative techniques and process optimization can significantly reduce energy consumption costs and enhance economic efficiency in plant-based meat production. For example, Sun et al., (2021) demonstrated that HME could produce plant-based meat products with superior texture and mouthfeel at lower operational temperatures, thereby resulting in energy savings and decreased production costs. Similarly, Zhang et al. (2022b) illustrated that optimizing processes within plant-based meat facilities led to a notable 20% reduction in energy consumption and a 15% decrease in waste generation. These advancements not only lower production expenses but also bolster the sustainability of PBM production.

Another promising approach involves integrating robotic systems for tasks such as ingredient mixing, shaping, and packaging. Automation in these processes reduces labor costs and minimizes human error, facilitating scalable and cost-effective production (Chen et al., 2022). Addressing these technical challenges necessitates a holistic approach combining technological innovation, meticulous process optimization, and strategic cost management. By adopting these solutions, the PBM industry can overcome existing limitations and achieve sustainable growth and competitiveness in the marketplace (Andreani et al., 2023; Kim et al., 2021; Zhang et al., 2022a) rather limits economies of scale, exacerbating cost challenges within the industry.

Regulatory issues

Other major challenges associated with entering burgeoning PBM markets encompass regulatory considerations, food safety protocols, labeling requirements, production cost-effectiveness, and the risk of marginalization from these sectors (Ahmad et al., 2022; Alcorta et al., 2021; Stagnari et al., 2017). However, unlike other meat alternatives, PBMs are subject to relatively less stringent regulations. In the United States, they fall under the purview of non-animal food products and are regulated by the Center for Food Safety and Applied Nutrition (CFSAN), overseeing aspects such as production, commercialization, labeling, and safety standards. Most PBM alternatives are derived from ingredients previously recognized as safe for human consumption. Similarly, the European Union categorizes plant-based alternative sources as non-novel food products, given their composition from plant sources such as soybeans, fava beans, peas, and lentils. Nonetheless, PBM may encounter more rigorous regulatory scrutiny if they incorporate genetically modified components, such as leg hemoglobin (Rubio et al., 2020).

Regulatory issues pose significant challenges for the PBM industry, but several solutions can address these concerns. First, establish robust traceability systems to monitor the sourcing, production, and distribution of PBM products. Ensuring adherence to strict regulatory standards and guidelines set by food safety authorities is crucial, including proper labeling, ingredient sourcing, and manufacturing practices. Policymakers might consider targeted subsidies to stimulate technological advancements and reduce economic burdens associated with PBM adoption, making these products more accessible. Enhanced regulatory measures aimed at reducing meat consumption should also be established to support the transition to plant-based alternatives. Collectively, these strategies ensure the safety, quality, and acceptance of PBM products in the market (Fesenfeld et al., 2023).

Socio-econmic challange

These challenges encompass the potential disruption of livelihoods for traditional livestock producers and feed crop farmers. Newton and Blaustein-Rejto (2021) undertook a survey within the United States, wherein they delineated threats encompassing potential livelihood or income losses for ranchers, livestock producers, and farmers engaged in cultivating crops designated for animal feed. Additional obstacles identified pertain to challenges encountered in transitioning towards emerging sectors involved in alternative meat production, along with the apprehension of being excluded from such sectors. This apprehension is rooted in the uncertainty of financial stability and the potential loss of established markets. Despite the portrayal of meat alternatives as environmentally advantageous, the magnitude of sustainability benefits derived from these products remains subject to ongoing deliberation and investigation. While there exists compelling evidence regarding the diminished environmental impact of legume cultivation (Stagnari et al., 2017), the efficacy of leguminous crops in mitigating GHG is contingent upon the specific management practices adopted within the agro-ecosystem, including considerations of monocropping versus conservation agriculture (Alcorta et al., 2021).

To address these challenges, several solutions can be implemented to increase the livelihood of cattle farmers. One approach is to use their land for cultivating leguminous crops in crop rotation systems featuring double-cropping, potentially enhancing profitability and augmenting the income streams of farmers who adopt such practices. Additionally, repurposing land or existing infrastructure to diversify or transition entirely into the cultivation of plants, algae, mycoprotein, seaweed, or other alternative protein products offers a strategic approach for livestock and animal feed farmers. This transition supports sustainable farming practices and opens new revenue avenues, aligning with the growing demand for plant-based protein sources. Furthermore, providing education and training programs for farmers can facilitate the transition, ensuring they have the knowledge and skills required to succeed in the new agricultural landscape (Newton and Blaustein-Rejto, 2021).

Future scope

The burgeoning preference for PBM is driven by their perceived positive environmental sustainability and their potential to mitigate the environmental impact associated with traditional animal agriculture practices. These alternatives are increasingly recognized for their ability to meet the rising global demand for protein sources, as supported by literature highlighting their nutritional benefits and eco-friendly footprint. Projections indicate robust growth in the PBM industry, expected to expand at a Compound Annual Growth Rate (CAGR) of 9.287% from 2024 to 2029 (Modor Intelligence, 2024). This growth trajectory not only signals economic opportunities but also fosters innovation across the plant-based meat supply chain. Agricultural farmers are researching new crops specifically tailored for PBM production, while food industry professionals are exploring novel market segments such as blended or hybrid meat alternatives. Additionally, food scientists are researching innovative approaches to formulate PBM that can more accurately assess sensory attributes in accordance with consumer perception.

Artificial intelligence and machine learning can be regarded as pivotal in transforming the development of PBM, offering sophisticated tools to enhance every stage of the process. Initially, AI algorithms analyze vast datasets to pinpoint plant ingredients with optimal taste, texture, and nutritional properties resembling traditional meat. ML models then predict ingredient combinations and proportions to achieve desired product characteristics, such as juiciness or tenderness, based on consumer preferences and sensory feedback. This predictive capability accelerates formulation processes, minimizing trial and error while ensuring product consistency and quality. Chefs, leveraging their creativity and culinary skills, play a vital role by crafting innovative recipes that showcase the versatility and delicious potential of these products across global cuisines. By integrating AI, ML, and culinary innovation, the PBM sector not only meets consumer preferences but also contributes positively to health, sustainability, and culinary diversity on a global scale.

Despite these advancements in the development of PBM, there remains a pressing need for application-focused research to thoroughly investigate how new technologies impact PBM products, consumer acceptance, and market dynamics. Rigorous studies are required to evaluate the practical implications of these innovations, assessing their effectiveness in real-world applications and their influence on consumer preferences and market trends. Such research will be crucial in understanding the full potential of these emerging technologies and their role in shaping the future of plant-based meat alternatives.

Abbreviations

PBM

Plant-based meat

GHGs

Greenhouse gases

LCA

Life cycle assessment

pI

Isoelectric point

NCD

Noncommunicable diseases

Funding

This work was supported by the University Grant Commission, India (Grant No. 190520217867).

Data availability

Not Applicable.

Declarations

Competing interest

No conflict of interest.

Consent for publication

Not Applicable.

Ethical approval

Not Applicable.