Extruder technology

Texturisation of Plant-Based Meat Substitutes

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The market for meat alternatives is growing. Raw material selection, optimal processing methods and flexible extruder technology are decisive for an authentic taste experience and a juicy texture with a bite.

Extrusion is a thermomechanical process that uses moisture, pressure, temperature and shearing forces to convert raw materials into a desired product. The processing of plant-based proteins poses many challenges. Technology plays an important role here. Coperion's hybrid modular food extruders offer configuration flexibility and allow manufacturers to easily switch between the production of Texturised Vegetable Proteins (TVP) and High Moisture Meat Analogues (HMMA). Both products are made from protein powder and water. However, the process conditions differ significantly.

To produce TVP, several process steps take place in the extruder. First, the raw materials are mixed to form a homogeneous melt. This is followed by kneading or plasticising and finally denaturing. In the process, the protein molecules unfold and reform to achieve the desired product structure. During the extrusion of TVP, the water expands into steam as it exits the extruder, causing the product to expand. The porous fibre structure of the material is created.

Similar process steps take place in the extruder for the production of HMMA. However, the water content required for HMMA products is significantly higher than for TVP. In addition, the extruder processing section must be longer to input sufficient energy for HMMA processing, where protein molecules denature and unfold, and protein agglomerates are separated.

Hybrid Extruder

Production parameters under control

The temperature profile, the screw speed, the moisture content and the discharge play an important role in the production process as well as for the product quality. After intensive mixing and cooking in the food extruder, the melt for TVP production is discharged through a die plate and cut at a centric pelletiser, while the melt for HMMA products passes through a special cooling nozzle. There, a laminar flow of the mass is forced and it is simultaneously solidified, forming fibres or meat-like structures. The emerging meat substitute product is in the form of a strand or ribbon.

Food extruder for quick product changeovers

With hybrid lines such as the ZSK Food Extruder from Stuttgart-based Coperion GmbH, it is possible to switch quickly between TVP and HMMA production. Both processes use the same twin screw extruder. However, the final product structure is achieved either via granulation for TVP or via a cooling nozzle for HMMA. Depending on the recipe, the configuration of the extruder process section with barrels and screw elements can remain unaltered despite the product change. With the help of an adapter solution, the food extruder's discharge can be converted from a centric pelletiser to a cooling nozzle and vice versa by the operating personnel in just one to two hours. This type of ZSK food extruder in its hybrid version is particularly useful for small to medium-sized companies, research institutes and start-ups. They offer an ideal opportunity to enter the fast-growing market for plant-based products. The higher the production rates, the larger the downstream process equipment needs to be. Consequently, in practice it no longer makes sense to accommodate both applications in one line above a certain size. In research and development or in pilot plants, on the other hand, the ZSK Food Extruder in its hybrid version is ideal for testing multiple recipes and different product types.

ZSK 43 Food Extruder070 Schatten Fogra39

Hybrid food extruders such as Coperion's ZSK allow manufacturers to quickly change between TVP and HMMA production. Copyright: Coperion

Industrial scale-up

The development of plant-based alternatives that come as close as possible to animal products in sensory terms and at the same time have a healthy nutritional profile and practical processing properties is never a foregone conclusion. Comprehensive tests and trials are always necessary until industrial scale-up. To this end, suppliers of ingredients and equipment now provide food manufacturers with comprehensive know-how, advice and technology to ensure that the development of a vegetarian product range is a success.

Meat substitutes

Vegetable proteins from different raw materials can be used in meat substitutes: besides soy, of course, wheat and peas, but also more exotic varieties such as duckweed. However, with its good texturising properties and mild inherent taste, wheat protein is the first choice for many manufacturers.

Regional raw material extraction stands for shorter delivery routes and more sustainability. High-quality wheat texturates such as BeneoPro W-Tex offer a good basis for plant-based alternatives. Most of the wheat used comes from Germany, Belgium and France and is processed into textured wheat protein at the BENEO plant in Wanze, Belgium. BeneoPro W-Tex consists of wheat gluten and flour.

Tailor-made for optimal results

The very mild inherent taste of the wheat texturate makes it easier to add the desired flavour to end products without any masking flavours. To ensure that it also impresses in terms of texture in products such as burgers, nuggets, sausages or chilli sin carne, comprehensive tests are mandatory at the BENEO Technology Center before delivery to the food manufacturer. All process parameters must fit exactly if the subsequent end product is to offer a juicy, yet firm-to-the-bite and fibrous meat structure. As with any natural raw material, there are product fluctuations in wheat. Even the smallest deviations in raw material quality, for example in the gluten used, can lead to undesirable results. If the extrudate is too hard, it will not be completely moistened within the targeted hydrogenation time. A disagreeably hard core would remain. If it is too soft, the water absorption capacity is enhanced, but the texture will not be as stable and firm to the bite as desired. It is the fine balance between complete hydrogenation and desired texture that makes the production of a perfect meat imitation so difficult. BeneoPro W-Tex simplifies this process considerably: In a maximum of 15 minutes it is completely moistened and can be processed further.

New legumes for the food sector

With an investment of 50 million euros in a production plant for processing field beans at its production site in Offstein, Rhineland-Palatinate, BENEO will be able to obtain protein concentrates from domestic field beans, among other things, starting in 2024. The line will initially focus on protein concentrate, starch-rich flour and the pods of the field bean. These products are excellent for protein enrichment and texture improvement in meat and dairy products as well as in (gluten-free) baked goods and cereals.