Current Technologies and Future Perspective in Meat Analogs Made from Plant, Insect, and Mycoprotein Materials: A Review

Abstract

This study reviewed the current data presented in the literature on developing meat analogs using plant-, insect-, and protein-derived materials and presents a conclusion on future perspectives. As a result of this study, it was found that the current products developed using plant-, insect-, and mycoprotein-derived materials still did not provide the quality of traditional meat products. Plant-derived meat analogs have been shown to use soybean-derived materials and beta-glucan or gluten, while insect-derived materials have been studied by mixing them with plant-derived materials. It is reported that the development of meat analogs using mycoprotein is somewhat insufficient compared to other materials, and safety issues should also be considered. Growth in the meat analog market, which includes products made using plant-, insect-, and mycoprotein-derived materials is reliant upon further research being conducted, as well as increased efforts for it to coexist alongside the traditional livestock industry. Additionally, it will become necessary to clearly define legal standards for meat analogs, such as their classification, characteristics, and product-labeling methods.

Introduction

The definition of a meat analog or meat alternative refers to the replacement of the main ingredient with a non-meat product, which can also be called a meat alternative, meat substitute, fake or mock meat, and imitation meat (Ismail et al., 2020). These products are principally made of pulses (mainly soy), cereals, or fungus protein, although the utilization of insects and seaweed as new protein sources has recently been considered (Megido et al., 2016). In fact, products made from plants, insects, and mycoprotein-derived substances are sold in the product market. These products are sold under the name of plant-based food, insect food, and mycoprotein food, which do not contain the word meat (CFR, 2023). While plant-based meat analogs are considered an attractive option to consumers, there are many limitations in traditional processing techniques used in the marking of meat analogs, which can lead to a loss of product taste and sensory quality, thereby reducing consumer acceptability (Grasso et al., 2021). Despite the increase in popularity and presence of plant-based meat analogs, there is limited evidence regarding the nutritional healthiness of these products (Melville et al., 2023). Indeed, plant-based meat analog technologies (meat shape, color, taste, etc.) have been developed and the market has increased; however, in recent years, the sales of meat analog have slowed and the industry stock prices have also begun to decline. Although meat analogs are attracting attention as an alternative to the consumption of meat, the main reason for the reduction in the growth of the related market is that the taste and quality of the product have not yet reached that of traditional meat products. In order for all meat analogs, including cultured meat, which has not yet entered the market, to grow in the current market, it is essential that technologies are developed to enhance their taste and quality. Therefore, this study was conducted to predict the future of the meat analog market by investigating the current technological developments and industrializations related to meat analogs.

Summary of Current Technologies and Industrialization in Meat Analogs Made from Plant-Based Materials

Plant-based materials are the most accessible materials for meat analogs, and have been consumed as food by extracting and processing plant proteins since the ancient times; tofu made from coagulated soybean protein, tempeh containing abundant lactic acid bacteria by fermenting soybeans, seitan made using wheat gluten from which starch has been removed, and falafel made using chickpeas (Cooper, 2015; He et al., 2020; Ismail and Kucukoner, 2017; Maningat et al., 2022). The plant-based food consumption includes not only processed-soy protein but also simple intake of high-protein plants such as spelt wheat, teff, quinoa, amaranth, oat, and hemp seeds (Balakrishnan and Schneider, 2022; Cooper, 2015; Crescente et al., 2018; Kahlon and Chiu, 2015; Mel and Malalgoda, 2022; Vega‐Gálvez et al., 2010). Table 1 shows meat analogs to mimic meat by processing plant-based protein. Most of the papers in the current literature described the below-used ingredients that were derived from grains or soybeans as raw materials. Diaz et al. (2022) processed fibrous meat analogs (FMAs) by extruding commercial oat fiber concentrate (OFC) and pea protein isolate (PPI) using twin-screw laboratory extruder. FMAs were made by adjusting the contents of OFC and PPI (Table 1). They supplemented the reduction in FMA texture due to the oat fiber by controlling the manufacturing temperature and confirmed that this characteristic was related to beta-glucan extract (Diaz et al., 2022). Similarly, a study using cereals (rice) and beans (soybeans) developed meat analogs with unique textures called textured rice protein (TRP; Lee et al., 2022). They prepared 4 types of TRP (TRP 25, 50, 75, 100) by adjusting the ratio of prepared rice protein isolate (RPI) and soy protein isolate (SPI; Table 1). A meat analog extruded dough with the ingredients above-mentioned along with cornstarch and wheat gluten (Table 1). By analyzing the extruded dough, they confirmed two things: 1) Protein molecules bind to water molecules, and water molecules are required for binding between protein molecules. Therefore, since the water affinity of RPI is lower than that of SPI, more elastic dough was formed in the treatment group with high SPI content. 2) The higher mass flow rate of the dough, the shorter the time it stays in the extruder, and reducing the degree of protein denaturation. SPI has a good affinity for water, so the binding force of the dough is very high, so the mass flow rate of the SPI dough is lower than that of the RPI. Mixing of RPI is required to lower the high mass flow rates (Lee et al., 2022). The addition of RPI reduced the porosity or water absorption ability of the final TRP, but this is a way to supplement amino acid components that may be insufficient with RPI and SPI alone (Lee et al., 2022). Therefore, a new possibility of implementing rice protein was presented to the meat analog raw material market, which subsequently concentrated on soybean protein. Another study attempted to replace fat as well as meat in meat analogs (Revilla et al., 2022). They made frankfurters by using olive oil to replace backfat and pea protein to replace meat. As pea protein was added, the color of the product became pale, but it was confirmed that up to 50% of meat can be replaced with pea protein. Nevertheless, this recipe using olive oil produced sausages with better emulsion stability and healthy fat compositions than using pork backfat (Revilla et al., 2022). Jung et al. (2022) used a special method called ‘ohmic’ to produce meat analogs. This method rapidly heated the meat analog by applying an electric field (AC voltage of 60 Hz), which enhanced the color condition of the product. During the ohmic process, changes in temperature, voltage, and current can be monitored by using a 34970A Data Acquisition system (Table 1). Chen et al. (2022) also used extrusion technology to prepare meat analogs. They combined amylose and amylopectin together for texture and bonding strength and suggested that the “sublayer transformation” that occurred during the extrusion was a key factor in producing a meat-like texture. In addition, it fixed the characteristics of the product by controlling the cooling die temperature after extrusion similar to Diaz et al. (2022; Table 1). Moreover, Keerthana Priya et al. (2022) specifically studied plant-based meat analogs (sausages) using jackfruit and banana florets (Table 1). They supplemented the lack of protein with some pea protein, which ultimately led to the development of a low-fat, fiber-rich vegan sausage. In addition, this vegan sausage contained the texture and physicochemical properties of a sausage that was sufficient to replace meat. This application involved the meaningful development of biomass, which can be used as a raw material in meat analogs alongside commonly used grains, legumes, and wheat flour. Some studies have focused on the fibrous and layered structure of meat analog products–for example, a study using pea and wheat proteins confirmed changes in the properties of meat analogs, which contained variations in the ratio of these two ingredients (Table 1; Yuliarti et al., 2021). Pea protein increased the firmness, chewiness, and viscoelasticity of the meat analogs, whereas wheat protein demonstrated the opposite trend. They confirmed that the meat analog structure was affected by the cross-linking rate between protein molecules and revealed that the most desirable meat analog formulation was obtained when the pea and wheat proteins were mixed at a ratio of 13:4 (Yuliarti et al., 2021). Kim et al. (2021a) and Kim et al. (2021b) conducted continuous research on manufacturing meat analogs with pulse proteins. Soy concentrate and soy isolate (soy-based protein) were mixed and used as control, and pulse proteins (PLP: pea isolate, pea protein, lentil protein, and fava bean protein) were combined as treatments (Table 1), and these are called high-moisture meat analogs (HMMA). According to this, soy-based HMMA formed the best fiber orientation, and treatment with PLP had less brightness, texture, color, and moisture content (Kim et al., 2021b). The use of a 2% brine solution has shown potential for being the most effective method in the preparation of HMMA (Kim et al., 2021b). In a follow-up study on the manufacturing of hamburger patties, the texture and sensory characteristics of the patties manufactured using general soy-based protein and patties using pulse protein were evaluated (Kim et al., 2021a). Patties containing pulse protein were more effective in reducing cooking yield and cooking time than control (soy-based protein) patties. Although the overall cohesiveness and texture preference, such as gumminess, was relatively low, it was evaluated as a sufficient substitute for general soy concentrate (Kim et al., 2021a). While legumes are predominantly considered a source of alternative proteins, peanuts have received relatively little attention (Zhang et al., 2020). Peanut protein powder was mixed with carrageenan, sodium alginate, and wheat starch and extruded to make a meat substitute. In this study, the meat protein structure and texture mimicry lacking in the peanut protein was improved through additives. It was found that the addition of carrageenan increased tensile resistance, sodium alginate increased fiber quality and elasticity, and adding wheat starch could improve the fibrous structure of the final product during extrusion (Zhang et al., 2020). Furthermore, Chiang et al. (2019) conducted a study to improve the quality of a soy protein concentrate meat analog by using wheat gluten. Wheat gluten contains gliadin and glutenin and plays an important role in maintaining the structure and binding (Chiang et al., 2019). The addition of 30% wheat gluten by weight effectively changed the fibrous structure of the meat analog. In the high-moisture extrusion process, disulfide bonds aided in the fibrous structure of the meat analogs, owing to the crucial role employed by the wheat gluten (Chiang et al., 2019). Prior to the study by Chiang et al. (2019), there were studies that used soybean protein and wheat gluten in the Couette cell technique (Krintiras et al., 2015). Here, they filled a Couette cell with a mixture of the aforementioned ingredients, along with water and salt, and analyzed the treated product. The Couette cell is a specialized product for dough behavior studies, although it has also been used to check the manufacturing conditions of meat analogs (Krintiras et al., 2015). Couette cell is based on the common concentric cylinder rheometer concept (Table 1). The manufactured product was used to confirm that the mixture could sufficiently structure the fibrous anisotropic and layered materials (Krintiras et al., 2015). Most of the previously mentioned studies used soybean protein as a replacement for meat protein, yet additional research to replace soybean protein is also underway (Keerthana Priya et al., 2022; Zhang et al., 2020).

Table 1. Current technologies for meat analogs made from plant-based materials

Since plant-based proteins are the most commonly used food ingredient with meat, research on their use as meat analogs forms the majority of reviewed research studies. However, almost all studies have focused only on the protein-fiber structure and nutritional and textural characteristics of plant-based protein products. Currently, plant-based materials have been found to be the most used material for manufacturing meat analogs. As a result of investigating many research results, it was found that meat analogs manufactured with plant-derived substances do not yet provide the same taste and quality characteristics as traditional meat products. Indeed, soybean types represent the most commonly used material for manufacturing meat analogs since they are thought to be high in protein, easy to obtain, and inexpensive.

Summary of Current Technologies and Industrialization in Meat Analogs Made from Insect-Based Materials

The edible insect market has been highlighted as an important future food market due to the rapid increase in population growth and it being a very environmentally friendly resource (Kiiru et al., 2020; Megido et al., 2016). People around the world have consumed locusts, mealworms, and slugs as snacks or side dishes and they were fried, sautéed or cooked in dry form (Choi et al., 2022; Yu, 2022). These recipes, which preserve the form of raw materials as they are, can create disgust for some consumers, which can be a factor that hinders their demand (Castro and Chambers, 2019). Nevertheless, insects are excellent meat analogs with high protein content of about 53.45 g per 100 g (Chen et al., 2010). Therefore, most insect materials have been added in powder form and used for cooking (cookies, protein supplements, etc.), and in this process, removing the peculiar odor of insects is one of the important pre-treatments (Liceaga, 2021; Mishyna et al., 2020). A list of meat analog studies using these insect-based materials is shown in Table 2. Baik et al. (2022) added Gryllus bimaculatus powder to a soybean meat substitute and 3D printed it, resulting in improved product texture. G. bimaculatus is an excellent food material among edible insects allowed in Korea due to its superior protein content (Baik et al., 2022). Compared to the control group with isolated soy protein added, the hardness and elasticity of the final product improved as the G. bimaculatus powder was added, with the characteristics of the 6% replacement treatment group being the highest (Table 2). Among them, the treatment group that replaced 3% showed the most similar texture to soybean-based meat, which had been prepared using soybean protein isolate as the control. Similar to isolated soybean protein, the more G. bimaculatus powder added, the more the texture characteristic of the meat substitute decreased; therefore, it was confirmed that the use of a binder should be considered to compensate for this (Baik et al., 2022). Megido et al. (2016) summarized western insect-based alternative meat and the views of the consumers on it. Mealworm (Tenebrio molitor L.), an edible insect, was prepared in powder form after fasting and was prepared into patties with beef or green lentil powder (Table 1). Participants (consumers) preferred the beef patty (BB) among the four total patties [BB, lentil (LB), mealworm/beef (MBB), and mealworm/lentil (MLB)] based on the overall liking and appearance. The next preferable tastes were, in descending order, the BB, MBB, MLB, and LB (Megido et al., 2016). This indicates the possibility that mealworms can effectively complement the taste of vegetable protein analogs and mimic the taste of beef. Kiiru et al. (2020) cooked SPI mixed with cricket flour (CF) using high-moisture extrusion, similar to previous studies on plant-based meat analogs. The temperature and water flow rate were adjusted to achieve a characteristic similar to meat, while a high temperature or low water flow rate increased the tensile strength of the product (Table 1). The treatment with crickets could form a denser fiber structure than the treatment with soybean protein alone, and the tensile and tenderness could also be improved (Kiiru et al., 2020). When comparing all treatments, the most meat-like product was produced when the 30% low-fat CF dough which was extruded at a water flow rate of 10 mL/min at 160℃ (Kiiru et al., 2020). Similarly, in a study using Alphitobius diaperinus and T. molitor, it was confirmed that the products prepared by mixing insect-derived protein concentrates with soy protein concentrates exhibited hardness similar to products made using soy protein (Smetana et al., 2018; Smetana et al., 2019). Initially, Smetana confirmed that mixing 40% A. diaperinus and 5%–10% soy fiber (soy dry matter) could produce meat analogs with a hardness, texture, and protein composition most similar to chicken breast (Smetana et al., 2018). Subsequent studies used both A. diaperinus and T. molitor, and when 15%–40% of both insect proteins were added, the texture of meat was effectively expressed (Smetana et al., 2019). In addition, the low hardness product was improved by increasing the barrel temperature of the extruder (170℃), confirming the basis for applying high-protein insect-derived materials (A. diaperinus, T. molitor) to meat analogs (Table 2; Smetana et al., 2019). In addition, by raising the barrel temperature of the extruder (170℃) to improve the low hardness product, meat analogs using high-protein insect-derived materials (A. diaperinus and T. molitor 40%) showed a texture similar to that of chicken breast or 100% soy protein concentrate (Smetana et al., 2019). Stoops et al. (2017) provided microbial information during the production and storage of ground meat products produced by adding two types of mealworm larvae (A. diaperinus and T. molitor). In addition, in order to realize the optimal taste and texture of the two mealworm larvae as a meat substitute material, other cooking methods such as steaming and frying were recommended (Table 2; Stoops et al., 2017). It was confirmed that minced meat products with mealworm larvae delayed the growth of microorganisms better than without, which suggests that meat analogues with these advantages could have prolonged shelf life (Stoops et al., 2017). Another study on patty manufacturing used only mealworm protein powder with bean curd (Kim et al., 2015). Here, the sensory evaluation result was the best when 20% mealworm powder was added to the total weight of the patty, which also resulted to a crude protein content of this patty was higher than in a general beef patty (Kim et al., 2015). In addition, it was confirmed that mealworm powder could produce nutritionally superior patties by containing sufficient amounts of protein and branched-chain amino acids (valine, leucine, and isoleucine; Kim et al., 2015).

Table 2. Current technologies for meat analogs made from insect-based materials

In the case of meat substitute manufacturing studies using edible insects, the focus was on reducing the negative perception of the nutritional, taste, or material of edible insects rather than imitating the structure of meat itself. Therefore, a large amount of manufacturing technology was applied in the case of mixing simple powdery materials with meat or vegetable analogs (such as soybean protein). Compared to plant-based materials, these studies mostly analyzed the preparation of meat mixtures rather than the meat itself. However, a number of studies were conducted on the pretreatment methods necessary to supplement the taste and texture to create a sense of incongruity with edible insects, and to confirm the possibility of their use as a meat substitute material. Research on developing meat analogs using insect-derived materials has used solely insects and has also mixed them with vegetable proteins (soybean-derived) in an attempt to make them similar to traditional meat products.

Summary of Current Technologies and Industrialization in Meat Analogs Made from Mycoprotein Materials

The last predominantly used meat analog material is mycoprotein, the process of which is shown in Table 3. In studies using mycoprotein, the main focus is on the safety of ingestion. While mycoprotein as an entity may be unfamiliar to the general population, the most familiar and similar material to consumers is mushroom mycelium. Bartholomai et al. (2022) suggested the possibility of manufacturing animal-free meat substitutes using Neurospora crassa mycoprotein, and these mycoproteins are prepared through rinsing and dehydration. Analysis of the possibility of toxicity and allergies relating to the protein of N. crassa for its use of the mycelium as a food product revealed no great risks. Moreover, N. crassa mycoprotein is a protei-rich source which also contains various fibers, potassium, and iron (Bartholomai et al., 2022). The protein obtained from Fusarium strain flavolapis contains all nine essential amino acids and has protein, fiber, vitamins, and minerals in semi-solid forms (Furey et al., 2022). It also has no mutagenic or genotoxic potential, so it is predicted to be sufficient to replace animal proteins (Furey et al., 2022). Sausages with added mycoprotein remains of good quality and microbial growth was not observed (Shahbazpour et al., 2021). Moreover, sausages with mycoprotein added have higher protein, lower fat, and lower carbohydrates than beef sausages, and have excellent water and oil binding ability, meaning less oil and water can be used during manufacturing (Shahbazpour et al., 2021). In addition, the content of essential amino acids and unsaturated fatty acids was higher than in beef, and the sausages were nutritionally superior (Shahbazpour et al., 2021). A review published by Ahmad et al. (2022) addressed the production, nutrition, and benefits of mycoproteins. Fusarium venenatum is the most famous mold used in the food industry processed with egg albumin and other additives (Ahmad et al., 2022). Furthermore, a mycoprotein extraction method using agro-industrial waste was presented. Extraction methods included submerged, the solid-state fermentation, and surface culture (Table 3). A method for producing mycoproteins by inoculating Paradendryphiella salina, Agrocybe aegerita, Aspergillus niger, and Rhizopus oryzae to wastes such as date palm, sugarcane, fruit, discarded bread, and brewer-spent grain was studied (Ahmad et al., 2022). Manufactured mycoprotein products have already been demonstrated to provide a rich supply of essential amino acids, proteins, and minerals, while the intake of these mycoproteins has been shown to affect blood insulin, glucose levels, lipid profiles, and muscle protein synthesis in subjects of different body types (Ahmad et al., 2022). In addition, the manufactured mycoprotein product has a texture similar to that of meat, resulting to high consumer preference (Ahmad et al., 2022). Interestingly, Gamarra-Castillo et al. (2022) made a hamburger patty using fungal protein (Aspergillus oryzae). They set up an optimal medium by adjusting carbon sources and its proportion with nitrogen to mass-produce A. oryzae (Gamarra-Castillo et al., 2022). After fermentation of the mycelia and undergoing a series of reactions to remove RNA, they were heated and a precipitate was obtained. Additives such as flour, binder, and colorant were used to improve quality when manufacturing patties with mycoprotein (Table 3). The most suitable medium additive for mycoprotein production was maltodextrin, which produced the highest biomass (Gamarra-Castillo et al., 2022). In addition, through analysis using an electronic tongue and texture analyzer, it was confirmed that the addition of quinoa flour, carboxymethyl cellulose, and beet extract produced products most similar to real meat (Gamarra-Castillo et al., 2022). In the study of Rousta et al. (2021), A. oryzae was mass-produced in a bioreactor system using oats to produce mycoproteins. They established optimal biomass production conditions by applying various concentrations of oat flour and temperature (Table 3). After the cultivation period, the biomass (mycoprotein) protein content increased from 11% to 37%, which were then dehydrated to make patties (Table 3; Rousta et al., 2021). In the evaluation of burger intake, consumers showed a tendency to either not particularly like the vegetarian fungi burger or to further dislike it (Table 3; Rousta et al., 2021). These negative results indicate that it is necessary to consider consumer-preferred taste and texture in using alternative proteins for food.

Table 3. Current technologies for meat analogs made from mycoprotein materials

Mycoprotein technology, unlike the other two technologies (plant and insect), focuses on the technology of processing the raw material itself. In particular, due to the nature of using mycelium, a lot of research has been conducted on conditions that can maximize mycelium production (Gamarra-Castillo et al., 2022) or basic technology to remove the effects of toxins, such as aflatoxin and fumonisin, which can be produced by mycelium (Bartholomai et al., 2022; Furey et al., 2022). Mycoprotein has a mycelial structure that is advantageous in mimicking the structure of meat, while its nutritional value is similar to or better than meat. Further, in some studies, it has presented physiological activity through ingestion, thereby demonstrating its value as a future meat substitute (Gamarra-Castillo et al., 2022). However, upon investigation, there are only a few studies that have evaluated the manufacturing of meat analogs using mycoprotein compared to other materials because it is relatively difficult to obtain compared to the more conventional plant-derived or insect-derived materials, while the related information on it is also limited. In addition, since mycoprotein is a material derived from fungi, there are also research issues related to safety. Therefore, in order to develop meat analogs using mycoprotein, additional research is required on both its safety and the fermentation method to obtain mycoprotein or the characteristics of the mycoprotein.

Future Perspective and Conclusion

Recently societal and scientific views have switched to believing that meat analogs made from plant-based, insect-based, or mycoprotein sources typically have a lower environmental impact compared to traditional meat production methods. Therefore, they are suggesting that choosing meat analogs made from alternative sources improves animal welfare by reducing the demand for animal-based products.

In terms of human health, plant-based, insect-based, and mycoprotein meat analogs often contain less saturated fat and cholesterol compared to traditional meat, which can be beneficial for cardiovascular health. They can also fulfill great dietary requirements relating to fiber, vitamins, and minerals that are beneficial for overall health. Moreover, meat analogs made from alternative sources provide options for individuals with specific dietary restrictions or allergies. The development of meat analogs made from alternative sources fosters culinary innovation and expands the range of available food options. However, there remains a lot of negativities surrounding meat analogs. Especially, regarding some meat analogs potentially containing additives, preservatives, or excessive sodium, which can negatively affect those seeking minimally processed or whole foods. Even though the taste and texture of meat analogs have continued to improve over time, some individuals still find them less satisfying or different from consuming meat; however, this can vary based on personal preferences and expectations. In terms of nutrition, they might lack certain vitamins (such as vitamin B12) or minerals that are in animal products; therefore, extra attention should be placed on maintaining a balanced diet. Additionally, meat analogs made from alternative sources can also potentially trigger allergies or sensitivities in some individuals–for example, insect-based meat analogs may not be suitable for individuals with insect allergies. Meat analogs made from alternative sources may face regulatory challenges or labeling issues, which can impact consumer confidence and clarity regarding their composition and nutritional information. Therefore, when evaluating meat analogs made from alternative sources, such as plant-based, insect, or mycoprotein, it is important to consider both the positive and negative factors associated. Although the market for meat analogs is likely to continue to grow, a number of important issues must be addressed: Firstly, the biggest obstacle to the growth of meat analogs is the lower preference for them by the consumer compared to traditional meat products. Therefore, to replace the consumption of traditional meat products, the texture or flavor of the alternatives must be very similar, yet the current meat analog products that are sold in the markets are not as highly rated by customers. Therefore, more research is needed that evaluates the health benefits as well as the texture and flavor. In addition, the conflict between meat analogs and the livestock industry remains an issue that national governments in each country need to solve. The argument between the meat analog industry and the livestock industry can be addressed through open communication, collaboration, and a focus on shared goals. Furthermore, the benefits and drawbacks of both meat analogs and livestock products should be promoted with full transparency to educate the global population. This would include, providing accurate information about the production procedures, nutritional profiles, and environmental impacts, which would help consumers to make informed choices. One more solution is the development of clear and fair policies and regulations that apply to both the meat analog and livestock industries. Unique characteristics and challenges are faced by each sector and need to be considered to ensure a level playing field, which supports innovation, consumer safety, and environmental sustainability. We recognize that both the meat analog industry and the livestock industry can contribute to addressing the overall global challenges, such as food security and climate change. Thus, collaboration on research and initiatives is highly encouraged to find sustainable solutions that benefit both industries and society as a whole.

Conflicts of Interest

The authors declare no potential conflicts of interest.