Quality Aspects Related to Meat Analogue Based on Microbiology, Plants and Insects Protein
2022 年 10 巻 p. 206-219
詳細
2022 年 10 巻 p. 206-219
Rapid global population growth has caused an increasing global consumption of meat and has resulted in the surging demand for meat analogue products over the last few years. There are many reasons why consumers and food producers are looking for alternatives to meat and meat products, including environmental, health, and ethical aspects. This study reviews recent scientific reports on quality aspects related to meat analogue based on single cell protein, insect protein and plant protein. The scope of the review includes the following: alternative protein sources, composition and nutritional value, and processing technologies of meat analogue. Protein from single cell protein (algae, mold, yeast, bacteria), plants (soybean, wheat gluten, legumes), and insects were described. The need for further research in this area, particularly on the nutritional value, technology for producing meat analogue, and food safety of meat analogue, was demonstrated.
The meat industry was currently starting to be overwhelmed to meet the increasing demand. By 2050, the global population will reach 9 billion people [1]. The large international population, combined with an increase in meat consumption in some developed countries, was expected to double meat demand in the coming years. Instead of being able to increase meat production, farmers have faced criticism for the negative environmental impact of their livestock activities. The livestock industry was unsustainable and triggered climate change. It was responsible for 14.5% of global greenhouse gas emissions and absorbed up to 30% of freshwater resources [2]. Establishing new farms was thought to encourage deforestation, cause pollution, damage hydrogeological reserves, and threaten the existence of biodiversity [2]. There will be many unfavorable impacts on the environment if we continue to rely on the livestock sector to meet our meat or protein needs.
The issue of animal welfare has also been criticized because there were animal handling practices that violate ethics and the excessive use of antibiotics to the risk of death. Quality alternative protein sources could come from plants, insects, microorganisms, or microalgae. The utilization of alternative protein sources was expected to reduce the negative environmental impact by up to 50% and result in significant ecological sustainability [3, 4]. In addition to environmental issues, red meat has also become a big problem for human health. Uncontrolled consumption of red meat, high in saturated fat, has contributed to the high incidence of cardiovascular disease. Currently, cardiovascular disease is one of the leading causes of death globally [5].
Non-animal-based protein foods exist in several countries. Countries in the Asian region have been consuming soybean products for more than 400 years. Product from soybean, tofu and tempeh were commercially available and were an inexpensive source of protein, attracting vegetarians and vegans who avoid eating meat for ethical, environmental, or health reasons [6]. Some consumers perceive protein-based products as lacking sensory appeal [7], mainly processed products that want to replace meat. It was because the off-flavor production almost always occurs, especially when using a protein source from plants. In addition, the natural fat content factor in the meat would produce a distinctive taste and texture of meat that was savory, soft fiber, and juicy. Extrusion with high humidity was one of the meat analogues (MA) production methods that achieved the most similar product structure to red meat [8]. Another effort was to use plant-based functional food additives or non-protein raw materials [9]. Food additives have been shown to improve sensory quality, especially texture and taste characteristics significantly.
Protein substitution from several vegetable sources has also been carried out to improve processed meat’s economic, functional, sustainability, and nutritional profile. Conducting research and identifying alternative sources of high-quality protein from various sources and converting them into MA products will significantly help planet Earth and humans gain future prosperity. The discovery of new technologies and optimization of alternative protein processing processes was necessary to develop MA. The MA sensory evaluation will provide important information regarding the selection of processing methods and raw materials to achieve quantitative and qualitative attributes at a certain level. The scope of major points the review includes the following: alternative protein sources, composition and nutritional value, processing technologies of meat analogue, prospective and future development challenges of meat analogs. Protein from single cell protein (algae, mold, yeast, bacteria), plants (soybean, wheat gluten, legumes), and insects were described detail. This study reviews recent scientific reports on quality aspects related to MA based on single cell protein, insect protein and plant protein.
The main thing about meat products was the availability of high protein nutrition and complete amino acids that are easy to digest. MA products, which were alternatives, must also provide this, perhaps even have other added values. Animal meat was the most complete and best source of protein for humans. The protein source of MA must be combined from several commodities to achieve the goal of a quality product equivalent to meat. In the following, the authors try to convey potential protein sources for compiling MA from single-cell protein (SCP), plants, and insects.
2.1 Single cell proteinSCP was dried microorganism cells utilized as a protein source in human and animal feeds. Algae, fungi (mold and yeast), and bacteria use inexpensive feedstocks and wastes as carbon and energy sources. Specific microbial proteases can convert these waste products into biomass, protein concentrate, or amino acids.
Microorganism species must be selected beforehand for SCP production. Fusarium venenatum species that have been used for mycoprotein production, the main characteristics are protein content at a yield of more than 45% and a fast growth rate [10]. In addition, for ease of application and safety, the selected microorganism species do not produce pigments, odors, and toxins. Other specific characteristics were usually added depending on the respective purpose, such as being able to use inorganic nitrogen and making a fibrous meat-like texture. Filamentous fungi were considered to have advantages, namely the production of hyphae which help form a more fibrous meat-like texture. Focus studies were needed when SCP was to be produced on a predetermined medium, such as by-products or waste (Table 1). They certainly have different chemical and physical characteristics, and the microorganism needs to be tested for their abilities. Fusarium venenatum reportedly met all the requirements and excluded more than 3000 other fungal species.
| Microorganism | Growth media and % Crude protein in yields | References |
|---|---|---|
| Algae | ||
| Chorella pyrenoidosa, Chorella sorokiana | Carbone dioxide through photosynthesis (40–71%) | [11, 18] |
| Chondrus crispus | ||
| Scenedesmus obliquus, Scenedesmus acutus | ||
| Spirulina maxima | ||
| Porphyrium sp. | ||
| Filamentous Fungi | ||
| Rhizopus oryzae | Fruit and vegetable discards (28.1%) | [37] |
| Rhizopus delemar | Bread Waste (36%) Potato protein liquor (53%) |
[38] [39] |
| Rhizopus oryzae, Aspergillus oryzae | Starch Plant Wastewater (35%) | [40] |
| Rhizopus oryzae, Aspergillus oryzae, Mucor indicus | Pulp waste (47%) | [41] |
| Aspergillus niger | Stickwater (48.7%) | [42] |
| Yeast | ||
| Saccharomyces cerevisiae | Cashew bagasse and guava peels (28%) | [43] |
| Candida tropicalis | Soy molasses (56.4%) | [44] |
| Kluyveromyces marxianus, Candida krusei | Cheese whey (43.4%) | [45] |
| Hanseniaspora uvarum, Zygosaccharomyces rouxii | Spoiled date palm fruits (48.9%) | [46] |
| Kluyveromyces lactis, Rhodotorula graminis | Waste milk (43.8%) | [47] |
| Bacteria | ||
| Lactobacillus acidophilus | Stickwater (68.4%) | [42] |
| Methylomonas, Methylophilus | Sewage sludge and the discarded effluent (41%) | [48] |
| Kefir sp. | Cheese whey (54%) | [49] |
| Bacillus pumilis | Potato starch processing waste (46%) | [50] |
| Corynobacterium ammoniagenes | Glucose and fructose (61%) | [51] |
SCP from algae was known as microalgae. Species explored to produce microalgae belong to the green algae group: Chlorella vulgaris, Haemotococcus pluvialis, Dunaliella salina, and the spirulina group: Arthrospira maxima and Arthrospira platensis. Dried microalgae contain 27%–64% protein [11]. Microalgae production was carried out in open ponds. Still, currently, many producers choose closed containers which are a custom source of energy because they are considered to have a lower risk of contamination. Microalgae biomass harvesting could be done by sedimentation, then dried by spray-drying. Microalgae proteins concentrated could be obtained by extraction. Mechanical methods can carry out the destruction of cell walls: crushing, crumbling, grinding, pressure homogenizer, or ultra-sonification, and non-mechanical processes: chemical treatment (acid, base, solvent, detergent), enzyme analysis (lytic enzymes, phage infection, autolysis), physical treatment (freeze-thaw, osmotic shock, heating, and drying). After which, the protein molecules were separated using centrifugation, filtration, or ultrafiltration techniques [11]. An important consideration that must be known was microalgae naturally absorb heavy metals from their environment. Either passively through surface absorption (live and dead cells) or their metabolic activities. The study results found that there were dietary supplements derived from Spirulina spp. and Chlorella spp. contain cadmium, mercury, and lead, although the levels are still below the tolerance limit for weekly human consumption [12]. The risk of contamination in microalgae becomes higher when using growth substrates in the form of waste or by-products from various industries. Toxic substances can also accumulate in microalgae significantly if the environment is contaminated with toxin producing cyanobacteria, such as Microcystis aeruginosa [13].
Mold and yeast have been used for the production of SCP. Proteins from molds are known as mycoproteins. Mycoprotein-based products from Fusarium venenatum under the brand name Quorn have been industrialized and have been in operation for more than 20 years [14]. Mycoprotein Quorn contains protein (45%), fiber (25%), fat (13%) and carbohydrates (10%) in 100 grams of dry weight [15]. Numerous fungi that could produce mycoproteins include Rhizopus oligosporus, Aspergillus niger, and Neurospora sitophila [16]. Yeasts Saccharomyces cerevisiae and Kluyveromyces marxianus are capable of producing SCP [17]. SCP derived from fungi will typically contain 30–50% protein. The amino acid composition of SCP from fungi is better with higher threonine and lysine content. In addition to protein, fungal SCP contains fiber and B complex vitamins such as thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), and folic acid (B9). Moreover, fungal SCP also contains other micro nutrition such as biotin, choline, streptogenin, glutathione, and p-aminobenzoic acid [15]. Consumption of mycoprotein from Fusarium venenatum was reported to cause low body cholesterol levels, glucose, and insulin levels.
Bacteria can also be cultured to become SCPs. The application of SCP of bacterial origin has already been carried out for animal feed mixtures. SCPs of bacterial origin generally contain 50–80% protein by dry weight [11]. The content of essential amino acids is also relatively complete. When compared to SCP from algae or fungi, SCP from bacteria contains higher methionine, up to 3%. In addition, the original SCP contains lipids and B-complex vitamins. The nucleic acid content in SCP from fungi was around 7–10% [18], and bacteria was approximately 8–12% [19], which was too high for human consumption because intake of a diet high in nucleic acid content leads to the production of uric acid from nucleic acid degradation. Uric acid accumulates in the body due to a lack of the uricase enzyme in humans [20]. Additional processing was needed to reduce nucleic acid content and involve chemical and enzymatic treatment. Each has disadvantages both in terms of cost and potential nutritional concerns.
2.1.2. Fermentation processSubmerged and solid-state fermentation are two methods for producing biomass or metabolic products of microorganisms. Maximum costs and benefits need to be analyzed to select the most appropriate fermentation method. Submerged fermentation is a process in which culture propagation is carried out in a liquid medium with lots of free water and dissolved nutrients. Submerged fermentation is divided into a batch, fed-batch, and continuous models. In the batch mode, the substrate is preloaded, the starter is inoculated, and the product is harvested at the end after incubation. In the fed-batch model, nutrients are added during the incubation process to increase the density and activity of cells in the reactor. While the continuous model, the addition of nutrients is carried out continuously in the reactor, and at the same time, the product is pulled out of the reactor. Solid-state fermentation is carried out by culturing the fungus on a solid substrate with sufficient moisture to support fungal growth. Examples of solid substrates that have been used are rice straw, beet pulp, nutshells, apple peels, and orange peels. The solid-state fermentation method has lower energy consumption [21]. However, maintaining process stability is more challenging than the submerged method. Often there is an uneven distribution of starter, nutrients, humidity, temperature, and acidity. In addition, harvesting SCP biomass from fermentation residues also has its challenges.
The design of the liquid state bioreactor can affect the growth of fungi in the submerged model. The bioreactor designs include stirred tank reactor, airlift reactor, and bubble column reactor [22]. The method of the bioreactor is also related to agitation, which ensures sufficient dissolved oxygen, acidity, and temperature are at optimal and controlled points. The second aspect that must be considered is the highly nutritious fermented substrate. The nutrient-rich substrate will maximize biomass growth. Fungi need organic matter as the primary source of carbon for energy production. There are at least eight macronutrients that need to be met: carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, sulfur, and magnesium, and there are five micronutrients: manganese, iron, zinc, copper, and molybdenum [16]. Organic carbon sources are sugars, such as glucose, fructose, and sucrose. Fungi can also use complex substrates such as lignocellulosic biomass for growth. Utilizing agricultural by-products to grow fungi biomass will lower raw material costs, reduce the environmental impact of agricultural results, and convert low-value materials into high-value products, for example, soybean dregs from oil extraction. Soybean pulp was previously used as animal feed, contains high protein, balanced amino acid composition, wide availability, low price, and has functional properties of soybean specific protein, including good gelling properties and water holding capacity [23]. The final yield of biomass and SCP levels may vary depending on the species, and the factors described earlier. Efficient technology must be continuously developed and adapted to its ultimate goal.
2.2 PlantsSoybeans contain about 30% crude protein. Soy protein consists of a mixture of soluble and insoluble proteins in water. Further processing of soybeans produces new products with different protein content. Soy isolate, processed by alkaline/acid precipitation or heat-treated, will contain about 90% protein. Soy concentrate contains 70% protein. Soybean juice, extracted from water from whole soybeans and then spray-dried, will produce a powder product with a protein content of 45–50% and about 30% fat. Meanwhile, the flour of soybeans contains about 50% protein [11]. The highest protein purity should not be chosen for MA applications, but the functional properties of the extracted protein should be more concerned. Soybean isolates obtained from acid precipitation have good functional solubility, gelling, and emulsion properties. Soybean isolates that were heat-treated during extraction decreased their solubility but increased their water holding capacity and were suitable for gelling. Likewise, soybean concentrate is good for forming MA textures, and soybean flour have high water holding capacity and fat retention properties [23]. Soy protein isolate can be mixed with gluten or other protein sources. The final goal needs to be studied more carefully, such as in sausages that prioritize emulsion and gelling functionalities.
Wheat gluten from wheat grains has also been used in processed meat products. The economical price is the main attraction. Wheat gluten isolate contains about 75–80% protein. In contrast to soy, gluten extraction from wheat is carried out by washing the soluble and dispersed components only with water, leaving the protein insoluble. Wheat gluten has the advantage of good binding and cross-linking capacity, that wheat gluten has the desired additional functionality, such as viscosity and swelling, and is high in carbohydrates and fat. The functional character of wheat gluten is very significant in the extrusion process, especially as a fibrous structure similar to whole meat and minced meat. It’s just that some consumers are gluten intolerant.
Legumes such as peas, lentils, lupines, chickpeas, green beans, and other types of beans can also be a source of protein for MA. Protein content in legume isolates can reach 85%. Protein from nuts has also been extensively researched and has been shown to have water and fat binding, emulsification, and firm texture after thermal processing properties. Other protein sources that have the potential to be used in MA mixtures are rapeseed, sunflower, quinoa, and other seed proteins. Peanuts, hemp, potatoes, and corn are also promising protein sources when applied to MA. Research shows that each protein from this commodity has its characteristics and is comparable to the use of soy protein, such in terms of oil binding, foaming capacity, higher viscosity, and gel formation after heating.
2.3 InsectsAccording to data from the Worldwide list of recorded edible insects [24], more than 2000 edible arthropod species. Entomophagy refers to the practice of eating insects. Edible insects are high in protein and polyunsaturated fatty acids. Adding insects to feed has been shown to increase body mass in animals significantly. Most edible insects are obtained from nature. Some are cultivated or domesticated through the manipulation of habitat on farms. The edible insects are the beetle Rhynchophorus ferrugineus [25] and the cricket Acheta domesticus [26], Gryllus bimaculatus [27], Teleogryllus testaceus, and Teleogryllus occipitalis [28]. Insect larvae or caterpillars are Tenebrio molitor [29], and Alphitobius diaperinus [30] can be utilized for protein.
Edible insects have been widely cultivated in the Asian region. Farmers used plastic containers, concrete, or plywood boxes to contain insects and fed them with chicken or plant-based feed, such as sago palm trunks, palm weeds, fruit, and vegetables discarded, or organic waste from households [28]. There are concerns about the potential to transmit pathogens or viruses from insects that may come from feed, the environment, or insect culture techniques. It is another challenge for insect farmers, and this topic needs to be studied comprehensively. Post-harvest processing of edible insects has traditionally involved thermal processes, such as boiling, frying, roasting, or drying by smoking [28]. The process carried out can remove contamination and moisture content, and the effect can extend shelf life. New technologies have also been used for protein extraction from insects, such as ultrasound technology and enzymatic hydrolysis [11].
Studies show that consumers who usually consume real meat are becoming interested in switching to MA with good nutritional benefits and sensory properties similar to real meat [7]. Popular MA product categories are minced meat (burger patties and nuggets), fibrous meat (chicken and beefsteak), and emulsion-type products (sausages). The content of macronutrients and micronutrients and any food additives must be informative. MA products must contain high protein with complete and easily digestible essential amino acid content. So, protein raw materials must consider the quality of the final product to be achieved. The selection of protein sources must consider the availability, ease of processing technology, and the costs incurred for processing [9]. Vegetable protein also mostly does not contain complete essential amino acids like meat, so it needs amino acid fortification from outside, such as the addition of rice flour or green beans, to get the amino acid lysine. Other specific problems will also be encountered when using SCP protein sources from fungi, insects, microalgae, and others. In order to obtain the desired specific meat structure, these proteins from alternative sources require more processing or are assisted by the use of food additives.
Carbohydrates are essential macronutrients that must be added to MA mixtures. Its function can replace myofibrillar proteins that form a texture and bind water in animal meat while also reducing the syneresis of MA products. Carbohydrates commonly used are polysaccharides such as starch, cellulose, pectin, xanthan gum, and others. Fat also has a significant effect on MA’s nutritional value and sensory properties. Fat will affect the texture and taste of the mouth. Besides, fat can be a carrier of fat-soluble vitamins. Some producers choose to use solid fat extracted from coconut and cocoa. Rapeseed oil, sunflower seed oil, sesame oil, and avocado oil have been shown to improve the product’s fatty acid profile and flavor [23]. The process that makes fat molecules into smaller lumps is reported to produce better emulsions and is preferred in burgers and sausages analogue. The concentration of natural fat from alternative sources is an advantage of MA, high in unsaturated fatty acids and low in cholesterol [23].
Color affects consumers when they want to buy MA products. The distinctive color of red meat can be formed by adding beetroot extract, which contains betaine, carrot, and paprika extract containing beta-carotene, or tomatoes and berries containing lycopene and anthocyanins. It should be noted that sometimes the color pigment will change or disappear during the thermal process. A biotechnological product, leghemoglobin has also been used for bloody meat characteristics. The characteristic aroma of animal fats not found in MA can be formed by adding various herbs and spices, such as black pepper, oregano, sage, rosemary, cloves, and others [31]. As a flavor enhancer, yeast extract and reducing sugar can be added.
Generally, food additives are added much more to MA products than real meat. The added food additives serve to mimic the sensory attributes of meat products and mask unwanted residual flavors from certain raw materials (e.g., nuts). Various techniques also need to be developed to remove undesirable flavors and reduce the use of food additives. Some food additives may be unavoidable to be added to MA products. The potential for vitamin B12, iron, and zinc deficiency is quite significant in a plant-based diet, so the addition of these three components is essential to improve the quality of MA. The addition of the transglutaminase enzyme may also be unavoidable because of its role in ensuring a solid protein binding to form a texture similar to animal meat. The addition of antioxidant components is also essential to prevent damage due to oxidation or rancidity so that the product's shelf life becomes longer [32].
The technology for producing MA depends on the type of meat product. Meat products can be categorized into ground meat products, minced meat, and whole fibrous meat. Many fibrous whole meat products are being developed with organoleptic properties similar to real meat. Commercial MA products have been produced using two technologies based on the process flow, namely bottom-up and top-down [33]. In bottom-up technology, the structural elements are made by a separate process. Components that have been formed are then assembled or combined with other ingredients into a larger product. The bottom-up technology follows the parts that make up the muscle structure in animal meat. Elements that act as muscle cells, such as mycoproteins, are prepared and then combined into larger muscles, myofibrils, sarcomeres with myosin, and actin until they are held together by connective tissue.
The second technology is called the top-down technique. Fibrous products are made by arranging a mixture of several raw materials to be processed into raw dough. The product is then molded, and the structure is formed from the combination and functional properties of the raw materials used. It means that the top-down technique mimics the structure of meat on a larger scale. Both technologies have advantages depending on the type of materials and equipment used. The processes applied the production scale, the quality of the final product, and the impact on the environment. Development is still being carried out in all stages of the process in both technologies, including appropriate raw materials.
Mixing, heating, and extrusion (low and high moisture) are the most established texturization methods to create meat-like structures. At the same time, there is new research on novel structuring methods such as shear cells, spinning, and 3D printing (Table 2). Mixing protein and hydrocolloid, which contain multivalent cations, such as alginate, which were pressed to reduce 40–60% water content [33]. The limitation of this method is that pressing the product in large quantities will damage the product fiber and reduce the quality. Vegetable protein from soybean, rice, corn, and other cereals can be used in this technique. If appropriately scaled, the resulting product can form a certain degree of structure. The freeze alignment freezing method has also yielded fibrous products. In the process, the protein solution is de-heated in the same direction without mixing, so that ice crystal needles will form and produce a porous microstructure. Freeze alignment methods have been studied for structuring meat [34]. The size of the ice crystal needle can be adjusted according to the freezing temperature and speed. The freeze-drying technique is then used to dry the frozen product without melting the ice crystals. The goal is to obtain a porous microstructure of protein molecules arranged in parallel sheets. As a note, the protein used in freeze alignment must have good solubility before freezing, and during the freezing process, the protein becomes insoluble.
| Process | Source of protein | Character of process | References |
|---|---|---|---|
| Wet and electro spinning | Plants | Complex, needed a highly concentrated plant protein solution, and was very expensive for large-scale applications. | [33, 52, 53] |
| Shear and heat by Couette cell device | Plants | Simple shear and heat at mild conditions, continuous and scalable processing. | [54] |
| High temperature (150 ℃) shear cell | Plants | Improve significant on water holding capacity, nitrogen solubility index, enthalpy of transition, and viscoelastic properties. | [55] |
| The high moisture extrusion | Plants, Mycoprotein | More complex recipes and does not require all ingredients to have a high solubility, leading to a more robust and cost-effective technology. | [10, 56] |
| Thermal plastic extrusion | Plant and Insect | 1. Dry extrusion (moisture < 30%) have limited acceptance because of their poor mouthfeel. 2. Wet extrusion under high moisture conditions (40%–80%) enables the production of fresh and premium meat analogues, with a muscle meat-like texture as well as a similar appearance and chewing sensation to cooked meat. 3. A high productivity and energy efficiency |
[57, 58] |
| 3D printing technology | Plants, Insects, and Single cell protein | 1. Rapid, precise, and productive as well as energy-efficient is required. 2. The quality of the product is not in accordance with consumer acceptance. |
[4, 59, 60] |
Shear cell technology has also been used to produce fibrous products. The fibrous product was obtained from a mixture of calcium caseinate with soy protein concentrate, soy protein isolate (SPI)-wheat gluten, and SPI-pectin [33]. It was also reported that the structure made with calcium caseinate showed anisotropy at the nanoscale, while for the vegetable, it was observed up to the micrometer scale. However, this shear cell technology has succeeded in developing a pilot plan scale.
Extrusion is a top-down technique for turning plant materials into MA. The resulting product can be low humidity or high humidity. Low moisture extrusion results from flour or protein concentrate as raw materials. The resulting product lacks water but will expand slightly when immersed in water. High humidity extrusion produces an effect with a moisture content of above 50%. Proteins were extruded by heating, hydration, and mechanical deformation processes. The extrusion also absorbs a lot of energy for the process, but it seems that extrusion is currently the most feasible technology for MA production.
Publications on technology for Quorn products have been used as a reference for the production of MA from SCP. After the fermentation process, the fungal cell RNA must be degraded into monomers by heat treatment. The biomass residue is then heated and centrifuged to obtain a paste-shaped concentrate with 20% solids [10, 14]. The resulting paste-shaped concentrate is then put into the forming, steaming, chilling, and texturizing processes to get a product with a uniform and fibrous texture. Commercial products that have been successfully produced from mycoprotein are minced meat, sausages, and burgers. However, some drawbacks were highlighted in the mycoprotein production process, such as the high use of resources and energy.
MA products are developing and experiencing many things that have attracted the attention of consumers and entrepreneurs. This product is considered an opportunity and a big challenge for entrepreneurs in the food sector. The first issue that needs to be considered with MA products is product descriptors and labeling [35]. Regulators in several countries prohibit the labeling of MA as “meat”, including processed meat-identical foods such as burgers and ham. The argument is for consumer protection because there is a risk of misleading consumers. In European Union countries, this issue continues to be discussed by scientists and regulators until, in 2020, it was decided that the term meat may be used for analogue products such as those derived from vegetable protein. This policy is similar to the “EU Protein Plan”, which aims to encourage the production and exploration of alternative proteins to substitute for animal protein [36].
There is another source of protein, namely meat culture, which has the same potential as an alternative protein source to substitute conventional meat. However, meat culture is currently considered to need more research, especially regarding its feasibility to be accepted by consumers regarding the use of genetic engineering and knowledge gaps about its safety. Cultured meat is real animal meat (including seafood and organ meats) produced by cultivating animal cells in-vitro in the laboratory [11]. This production method eliminates the need to raise and farm animals for food. Cultured meat is made of the same cell types arranged in the same or similar structure as animal tissues, thus replicating the sensory and nutritional profiles of conventional meat [11]. The manufacturing process of cultured meat begins with acquiring and banking stem cells from an animal. These cells are then grown in bioreactors at high densities and volumes. Like in an animal’s body, the cells are fed an oxygen-rich cell culture medium made up of essential nutrients such as amino acids, glucose, vitamins, and inorganic salts and supplemented with proteins and other growth factors [11]. Changes in the medium composition, often in tandem with cues from a scaffolding structure, trigger immature cells to differentiate into the skeletal muscle, fat, and connective tissues that make up meat [11]. The differentiated cells are harvested, prepared, and packaged into final products. This process takes 2–8 weeks, depending on what kind of meat is cultivated.
By nature of its more efficient production process, cultivated meat and meat analog are expected to have various benefits over conventional animal agriculture. Prospective life cycle assessments indicate that cultivated meat and meat analogs will use less land and water, emit fewer greenhouse gases, and reduce agriculture-related pollution and eutrophication. Commercial production is expected to occur entirely without antibiotics and is likely to result in fewer incidences of foodborne illnesses due to the lack of exposure risk from enteric pathogens. Over the next few decades, cultivated meat, meat analog, and other alternative proteins will take significant market share from the $1.7 trillion conventional meat and seafood industry. This shift will mitigate agriculture-related deforestation, biodiversity loss, antibiotic resistance, zoonotic disease outbreaks, and industrialized animal slaughter [11].
MA can be described as an alternative food with a nutritional value equivalent to healthier animal meat for consumers. For this reason, the formulation of alternative proteins with functional food additives must be oriented to the health impact that consumers will get. The digestibility of vegetable protein is generally lower than animal protein. In addition, the availability of vitamin B12, zinc, and sufficient iron in animal meat must be considered and fulfilled by MA producers when developing products. MA is thought to be able to target consumers with certain beliefs and lifestyles. Labels such as Halal for Muslims, Kosher for Jews, and Vegan can be obtained, apart from other detailed requirements that may need to be adjusted.
MA available today are continuously being improved on their organoleptic qualities. Manufacturers compete by using cutting-edge texture-forming techniques and functional ingredients with sensory properties similar to animal meat. However, the effort to create MA that is close to animal meat impacts another aspect, namely the use of more synthetic food additives or non-protein substances. At the beginning of its appearance, MA had good advantages for a balanced diet, such as being cholesterol-free, low in calories, and high fiber content compared to animal-based meat (Table 3). However, some processed products, such as analogue burgers, must use coconut fat and cocoa fat to get the desired quality, resulting in a higher fat content [32]. The large variety of raw materials for MA production also makes it challenging to confirm firmly and consistently that this product category is superior in nutrition to animal meat.
| Components | Non-animal based | Animal based | |||||
|---|---|---|---|---|---|---|---|
| Beyond burger (113 g) |
Impossible burger (113 g) |
Quorn vegan burger (100 g) |
Quorn fillet burger (100 g) |
Field Roast burger (92 g) |
Boca XLburger (141 g) |
Hamburger (90 g) |
|
| Calories | 230 | 240 | 199 | 221 | 240 | 230 | 266 |
| Protein (g) | 20 | 19 | 13 | 12 | 21 | 28 | 19 |
| Fiber (g) | 2 | 3 | 6.7 | 6 | 2 | 9 | 1,1 |
| Total fat (g) | 22 | 14 | 7.3 | 12 | 12 | 8 | 23 |
| Saturated fat (g) | 5 | 8 | 0.6 | 2.1 | 4 | 2.5 | 9 |
| Cholesterol (mg) | 0 | 0 | - | - | 0 | 10 | 80 |
| Sodium (mg) | 390 | 370 | 100 | 140 | 610 | 770 | 396 |
| Iron (% daily-value) | 25 | 25 | - | - | 8 | 25 | 12 |
Safety aspects must still be considered in MA processing. Long and intensive processing risks the formation of new harmful compounds such as heterocyclic aromatic amines, N-nitrosamines, and polycyclic aromatic hydrocarbons. Other safety factors can also arise, such as pathogenic bacteria from raw materials, anti-nutritional components (protease inhibitors, phytic acid, and oxalic acid), pesticide residues, heavy metals metal contamination, and the potential for allergies from alternative proteins used. Modern preservation methods can be used to avoid synthetic preservatives. A suitable method for meat products, in general, is preservation at low or non-thermal temperatures [33]. Innovative packaging, for example, containing active clay, can also be a promising tool to ensure the shelf life and safety of MA products.
The success of MA products is related to the consumer’s decision to buy. The price of the product is a parameter that must be formulated. MA raw materials derived from vegetable protein are much cheaper than the cost of animal care on farms. However, the high cost of processing and other additives will contribute to the final price of the MA product. The strategy that producers need to take is in product marketing efforts. The clarity of the label and the consistency of the message to consumers are important issues, such as the sustainability of production and the "naturalness" of the product. In the future, manufacturers must focus not only on overcoming technological difficulties in shaping the texture and taste of products but also on improving nutritional value, the safety of consumers, and optimizing processes to reduce costs and balance environmental impacts.
The MA industry has successfully shaped a growing global market in recent years. This paper has discussed the critical component of MA, namely protein. Alternative proteins can be selected from sources that do not cause environmental disturbances and do not raise ethical issues. MA products should have health aspects, namely from the content of bioactive compounds, high in dietary fiber, cholesterol-free, and low in saturated fat content. The challenges that MA producers and researchers must solve include finding new technologies and ingredients to get the best correlation between composition and texture and sensory properties. Safe processing, consumer safety, and clean labeling of MA products must also be continuously pursued by researchers and producers.
The author would like to deepest thank all parties who have helped in the completion of this research.
