Meat of the Future - "Meat" from Plants?  [15.06.21]

At the Meat Technology Technical Center at the University of Hohenheim, scientists are investigating how animal proteins can be replaced by plant proteins. Image: University of Hohenheim | Astrid Untermann | more press photos in print quality

Once a year, an additional issue of the magazine "Bild der Wissenschaft" is devoted to a single topic. This year it is about "biointelligence." It stands for a system in which biological and technical principles merge and the consumption of natural resources is transformed into a cycle of use, processing, and recycling - in short, an all-around sustainable system. Together with others from the Stuttgart region, researchers from the University of Hohenheim report on how this can be achieved. We present the articles by the Hohenheim researchers in a series.

Bild der Wissenschaft Special "Biointelligence", approx. 100 pages, € 8.20: now available at newsstands

For health, ecological, and ethical reasons, more and more consumers are already foregoing the consumption of animal proteins. They are increasingly turning to products made from vegetable proteins instead. But not everyone wants to give up meat completely. If you want to persuade people to change their behavior, you have to offer them something that appeals to them at least as much or even more than what they are used to. That's why scientists all over the world are working on new recipes.

This is also the case at the University of Hohenheim in Stuttgart and at the German Institute of Food Technologies in Quakenbrück. There, experts want to use plant proteins to make products that not only look like meat, but also feel like meat in the mouth and taste like meat. After all, many market research studies have shown that die-hard meat lovers are only willing to switch to plant-based alternatives if the sensory quality is right.

Bild der Wissenschaft Spezial „Biointelligenz“, ca. 100 Seiten, 8.20 €: jetzt am Kiosk erhältlich

Apart from the taste, the texture of the product is decisive for the feeling of having a piece of meat or sausage in one's mouth. That's why Jochen Weiss, a professor at the University of Hohenheim, and his team are looking for a way to mimic the texture of meat-analogous products made from plants in such a way that they resemble the structure of meat to the point of confusion. This also has another advantage, explained the process engineer: "The improved feel in the mouth means that the amount of additives and flavorings can be significantly reduced." Which in turn also leads to greater consumer acceptance.

This is an assessment shared by Beate Gebhardt, a consumer researcher at the University of Hohenheim. The head of the qualitative sub-study of a survey of consumers and experts in six European countries, "The V-Place," observed, "Particularly on the part of vegans or vegetarians, there are health reservations about plant-based foods. The reason often cited is the very high degree of processing or the additives used, such as salt, sugar, stabilizers, or other additives."

Texture is key

The appearance and taste of meat can be mimicked relatively easily with plant-based substances. But not its consistency. That's because meat, and especially muscle tissue, is a complex structure of bundles of long, thin protein fibers with embedded fat. The whole is held together by a firm connective tissue. In contrast, plant proteins do not form fiber bundles. This is why many first-generation vegan products, in which vegetable protein was added only in powder form rather than as fibers, failed. The products lacked not only the desired taste, but above all the typical feeling of meat. Their consistency was more reminiscent of cheese than sausage.

Today, thermomechanical processes can be used to selectively texture plant proteins to produce fibrous structures. The result resembles meat in appearance, color, and texture. The most commonly used method is extrusion. For this, vegetable protein powder is first heated with water and spices. The dough-like raw material mass is then pressed through a cooled nozzle with the aid of screw shafts. In the process, the proteins crosslink and obtain a pleasant, fibrous structure. This so-called "wet extrusion" is mostly used by manufacturers when the end products are to resemble the animal products as closely as possible in terms of consistency and shape. The consumer can process them directly, like a piece of meat.

Another process, "dry extrusion," uses less water. This produces more sponge-like structures, like those found in peanut flips. This method is mainly used for the production of textured soy. The starting material is defatted soybean meal, a by-product of soybean oil production. Textured soy is high in protein, low in fat, and has virtually no flavor of its own. In stores, it is usually found in dried form as soy meat or soy cutlets, which often have to swell in water or broth before they can be used.

Meat - a "tissue" of fat and protein

But protein structure alone does not make "meat." The fatty tissue of pigs or cattle consists of liquid and solid fat. Most dietary fats are mixtures of different triglycerides with different melting and crystallization temperatures. Depending on the ambient temperature, such mixtures may contain both a solid and a liquid portion. In this case, the solid portion is present in the form of crystals, which may aggregate to form larger fat crystal flakes. These flakes, in turn, are either present as individual particles in the liquid phase or form a three-dimensional network. The result is a kind of gel in which liquid oil is surrounded by structures of solid fat. When subjected to mechanical stress, animal fats therefore exhibit plastic behavior: They are irreversibly deformed when stressed beyond a critical value. This plasticity is desirable in many foods, such as butter, because it contributes to their spreadability and a creamy or buttery feeling in the mouth.

In addition, animal fat tissue also has elastic properties, which it owes to its structure. This is because this network of crystalline and liquid fat components is embedded in fat cells that are held together by a connective tissue matrix. This consists mainly of collagen, a protein with unique properties. For example, it is capable of forming highly elastic gels of considerable strength. Vegetable proteins, on the other hand, have little tensile strength and are poor at retaining moisture, which prevents gel formation. The art of producing meat-analog products is now to mimic this mixed network of proteins and fats with crystalline and liquid portions.

But there are other ideas and approaches for mimicking the complex structure of fatty tissue. The process engineers in Hohenheim, for example, are pursuing yet another approach to structuring fats. They first add an excess of protein to a melt of oil and solid vegetable fat. A special enzyme, transglutaminase, cross-links the individual proteins with each other, creating a three-dimensional structure. On cooling, a lattice of fat crystal flakes is also formed, into which droplets of liquid oil are embedded. "This allows us to reproduce the typical plastic character of a fat crystal lattice with elastic properties that consumers associate with animal fat tissue," Weiss stated.

A lot of know-how had to be developed

The development of such plant-based fat matrix structures makes it possible to offer customers a wide range of products that also meet with their approval. Among other things, such fat systems are used as structural elements to produce a variety of vegan meat product analogs such as "vegan sausages" or "vegan burger patties." Here, the mechanical and thermal properties of the fatty tissue are of particular importance for processing. One critical point in particular is the comminution process, in which the typical meat structure must be preserved. This is because for many foods, such as raw cooked sausages, it is crucial for the characteristic sensory properties that they have distinct particles and do not just consist of pasty material.

The researchers are also paying particular attention to the sustainability of the starting material. For example, oil press cake produced during the manufacture of rapeseed oil often still contains enough protein for the production of meat analogs. Other side streams from the food industry can also be used in this way. For ecological reasons, the starting material should also be plants that can be cultivated in Germany or Europe and thus do not require long transport routes. The scientists therefore tested various domestic protein sources, such as potatoes, peas, and pumpkin and sunflower seeds. "Peas proved to be the ideal starting material for protein extraction," said Weiss, summarizing the research results.

In the past, the use of pea proteins often led to a so-called "off-flavor," i.e. a flavor that did not fit with the product and that could hardly or not at all be masked by spices. "This is because peas also contain fat," Weiss explained. "Although the proportion is only seven or eight percent, over time the fat oxidizes and then leads to these off-flavors." Since the researchers have known this, fat-free pea proteins can easily be used to make vegetarian or vegan meat alternatives. For example, a meatball to which 20 percent pea texturate has been added can hardly be distinguished from the pure meat version.

Meat hybrid - substitution of animal proteins with vegetable proteins

The example of the meatball shows how well extruded plant proteins can be mixed with meat. They have little effect on the animal ingredients and also have a supporting effect on texture. In these so-called meat hybrid products, high-quality plant proteins are incorporated into meat products. For example, 25 to 50 percent of the meat in a meat product, such as a meat sausage, salami, or meatball, can be replaced with plant proteins.

These products are an option to meet demand while making meat products more sustainable. In this regard, the production of hybrid convenience products, i.e., the grinding of the texturates in the meat cutter and the blending of the components, is comparable to that of pure meat products. Existing processes and equipment used for the production of meat products can thus also be used for the production of vegan sausage products. For small and medium-sized companies in particular, this opens up a new market segment without having to invest in new equipment.

For meat lovers, meat hybrid products represent a low-threshold offer to switch to a lower-meat diet. Meat substitutes made partly or entirely from plants can thus play an important bridging role in reducing meat consumption and facilitate changes in culturally developed eating habits. In Germany, but not only here, a large proportion of consumers still consider meat to be indispensable in their daily diet. Scientists refer to this as "meat attachment" or, to put it simply, "love of meat. The stronger this "meat attachment" is, the less people are willing to turn to vegetarian or vegan substitute products.

But those consumers who actively want to reduce their meat consumption, known as flexitarians, are expected to have high potential. In 2020, Forsa estimated the proportion of flexitarians in Germany at 55 percent. Regardless of the exact figures, however, a clear trend has been emerging for years: more and more people want to eat less and less meat. At the same time, however, many of them do not want to give up the taste of meat and therefore turn to meat substitutes. The food industry has also discovered vegetarian and vegan meat substitutes. In the meantime, the range of products extends from the well-known soy schnitzel to sausage products and vegan burgers, in which patties, cheese, and bacon are made entirely from plants.

However, the extent to which vegetarian and, in particular, vegan products can achieve relevant market shares in the long term will depend heavily on whether consumers accept them as an equivalent alternative to animal meat and sausage products. The general population will probably only be prepared to replace meat completely with plant-based alternatives if they are offered a tastier, higher-quality, lower-priced substitute product.

This is also shown by the survey results of consumer researcher Gebhardt: "An unappealing taste, a lack of product range or too little product variety, and too expensive a price are frequently cited as reasons for not buying plant-based foods." And what are the reasons consumers do choose plant-based foods? "General health, animal welfare, and environmental or climate protection are important motives for consuming plant-based foods in all the countries considered, but not the only ones," Gebhardt stated. "In addition, health aspects such as food intolerances or allergies, but also religious reasons and individual openness to new products play a role in the purchase decision. There is then also scope for completely new recipes and flavors that are detached from the animal original," she said.

Plants as the basis for the nutrition of the future

Particularly in industrialized nations, with their high consumption of animal-based foods, the health consequences of regular consumption of larger portions of meat and meat products often become apparent: Cardiovascular disease, high blood pressure, stroke, type 2 diabetes, and colon cancer, to name just the most common. It is not without reason that many people want and need to rethink their meat consumption.

Vegetable substitutes can be a good alternative - also in view of a steadily growing world population. After all, meat can feed far fewer people than the food needed to produce it. This is mainly because plants can be used directly for human nutrition. The "detour" via the animal and thus also the loss of calories during the conversion of plant-based feedstuffs into animal meat is eliminated.

Since this drastically reduces the need for land and water, the environment and climate also benefit. The German Institute of Food Technologies (DIL), for example, has calculated that a sausage made from plants requires only 51 percent of the energy, 33 percent of the water, and 30 percent of the land area of a classic sausage made from meat, and produces only 36 percent of the CO2 emissions. So there are plenty of reasons - at least in industrialized nations - to significantly reduce consumption of animal-based foods and increase consumption of plant-based alternatives.

Text: Ursel Stuhlemmer / Translation: Neudorfer

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