Proteins play an important role in human nutrition by providing building materials essential for both growth and cell regeneration. First of all, most of the meat alternative food sources from which proteins can be obtained differ in the composition of proteins themselves, as well as their amino acid profiles.
More and more people are avoiding plant-based products, which are very interesting in terms of nutritional value, vitamins, micro and macro elements, and the ability to counteract some of the diseases prevailing among the civilization, due to their cholesterol and blood pressure lowering properties.
Most meat analogy are based on two proteins: soy and gluten. Soy protein is a good alternative to meat in terms of amino acid composition and textural properties. However, the use of soy is quite controversial among consumers due to genetically modified (GM) crops. There is a study showing that 55% of consumers are opposed to GM foods and nearly 60% do not trust GM scientists.
In 2020, the market value of plant-based-meat worldwide was estimated to be worth USD 6.67 billion. This figure is estimated to steadily increase over the next few years and reach roughly 16.7 billion in 2026.
What is an Alternative Protein?
Alternative proteins, also known as plant-based proteins or meat substitutes, refer to food products that are designed to mimic or replace traditional animal-based proteins like meat, poultry, and seafood. These proteins are created using various sources such as plants, fungi, algae, and even lab-cultured cells.
Protein sources for Alternative protein
1. Legume Proteins
The seeds of leguminous plants are characterized by their high nutritional value. Compared to other plants, they are distinguished by a fairly high protein content, ranging from 20% to 35% on average, depending on the type, growing conditions, and degree of maturity.
In the protein of legume seeds, two fractions are distinguished: albumin and globulin. Albumins make up 10–25% of the total protein, can be soluble in water, and are mainly found in the germinal part, globulins are soluble in dilute solutions of neutral salts.
Each and every species in legumes provide different amounts of protein to organisms.
There are many species of legumes such as peas, lentils, lupins, chickpeas, broad beans, and mung beans. Every species of legumes has individual protein content and several health benefits. Among all these Lupin seeds have higher protein content around (46%).
2. Oilseeds Proteins
In recent years, many oilseeds have been used as sources of protein in the food industry.
Their antioxidant, antihypertensive, and neuroprotective properties make them a valuable and functional alternative source of protein, e.g., in the baking and meat industry.
The oil plants used as a source of protein include, inter alia, soybean, chia seeds, evening primrose, flaxseed (brown), hemp seeds, milk thistle, nigella seeds, pumpkin seeds, rapeseed, sesame, safflower, glandless cottonseed, and sunflower seeds.
In addition, these proteins complement desirable functional properties when added to certain foods; this applies to whipping capacity, viscosity, emulsifying capacity, and water and oil binding capacity.
Among the many benefits of proteins obtained from oil plant seeds, one should also remember the dangers of plants such as rapeseed that contain, in addition to many nutrients beneficial for the human diet, toxic erucic acid and sulfur compounds—glucosinolates, which are a component of the protein fraction.
3. Cereal and Pseudocereal Proteins
In grain-based proteins used in meat analogs, wheat, oats, or rice are used. The most common is wheat protein, which is gluten, due to its viscoelastic properties.
Cereals that are high in protein are pseudo-cereals like amaranthus and quinoa. Amaranth and quinoa grains are equally good as cereals and legume seeds because of their high content of lysine, arginine, tryptophan, and other sulphur-containing amino acids. Amaranth is an example of a plant with a high protein content of up to 14%. Some difficulty in obtaining protein is the isolation of starch in the case of amaranth, However, amaranth has already been successfully used as a binding agent in sausage formulations.
Another type of pseudo-cereal used in meat products is quinoa, a raw material with approximately 8% protein but a very high nutritional value containing all nine essential amino acids.
4. Algae Proteins
Algae, or photosynthetic eukaryotes, are distinguished as microalgae and seaweed.
Microalgae and seaweed also contain more protein per unit area (4–15 tonnes/Ha per year and 2.5–7.5 tonnes/HA per year, respectively) in comparison to soybean (0.6–1.2 tonnes/Ha per year) or wheat (1.1 tonnes/Ha per year). Depending on strain and cultivation conditions, microalgae can produce up to 70% of proteins in cells compared to 30–40% for soybeans. Even more important from the quantity of protein occurring in algae is its quality.
Two most dominant microalgae species on the market, Spirulina (Arthrospira) and Chlorella, are characterized by the higher than standard (100) essential amino acids index (102.6 and 107.5, respectively). Those values are similar to casin milk protein and higher than soybean meal.
5.Insect Proteins
Insects are common food for 2 billion people in 119 countries across the globe.
There are over 2000 edible species. The most consumed insects that are used as protein sources are Coleopatra Beetles (31%), Lepidoptera Caterpillars (18%), Hemynoptera, wasps, bees, and ants (14%).
However, those are still novel foods for Western countries. This is slowly changing due to growing need for alternative sources of proteins, production of which would be more sustainable.
Studies on the life cycle assessment of Hermetia illucens performed by Smetana et al., (2019) revealed that insect protein concentrates had a lower environmental footprint than animal proteins but higher than plant proteins.
Insects are a good source of proteins. The average content of proteins in them is 40% and ranges from 20% up to 70% depending on the species. Three species that are widely bred in Europe (Tenebrio molitor, Gryllodes sigillatus, Schisocerca gregaria) are considered to have the biggest potential as food components in the European Union and contain 52.35, 70, and 76% of proteins, respectively.
Insect proteins are more digestible (76–98%) than plant proteins (lentils 52%) and slightly less digestible than animal proteins (95% egg protein, 98% beef protein) [60]. The essential amino acids’ score for insects ranges from 46% to 96%, which greatly exceeds the lowest recommended level for human diets (>40%).
Furthermore, insect-derived food and feed might be contaminated chemically with heavy metals and biologically with spore-forming bacteria.
6. Edible Fungus Proteins
Mushrooms have been classified into a separate kingdom because of their different cellular organization, and they do not belong to either animals or plants, Fresh edible fungus has about 90% water, and the remaining 10% dry matter is composed of 8–40% protein, 3–28%.
Yu et al., (2020) examined 23 edible mushrooms and determined their protein content. It was found that the protein content in edible mushrooms was approximately 8.5–36.9%, which was much higher than that of vegetables, fruits, and grains. The higher protein content was found in Trichloma (36.87%), and Tremella had the lowest protein content (8.46%). Other more popular mushrooms like Shiitake, Lentinus Edodes, Volvariella Volvacea, and Boletus had a protein content of 15.38%, 11.59%, 10.24%, and 12.16%, respectively.
Mushrooms and fermented products have a meaty taste, a long shelf life, good nutritional values, and reduced cooking time, so they can be a new generation of plant proteins in the future.
Conclusion
Today, more and more consumers are turning to vegetarianism or looking for products that are not based on animal products. This is understandable from the point of view of worldview, religion, or often just the search for new tastes. In most meat analogs, we encounter proteins of soy origin and wheat origin, like gluten.
The increase in demand for plant-based protein will certainly be seen in future years as we look for new sources of protein to meet the needs of a growing population. In developed countries, more consumers are turning to vegetarianism and veganism, which will also contribute significantly to the demand for such protein sources
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