There are many approaches to creating plant-based meat- and poultry-type products. Extrusion technology is often part of the process, especially with products designed to mimic whole muscle. To better understand the technology and its capabilities, MEAT+POULTRY spoke with Gilles Maller, vice president of sales and international, and Julie Prost, process engineer, at Tampa, Fla.-based Clextral, a manufacturer of extruders.

MEAT+POULTRY: How is extrusion used in the manufacture of plant-based meats?

Gilles Maller: Analogs encompass a wide variety of products, ranging from dry texturized vegetable proteins that need to be rehydrated, to truly meat-like products with the realistic appearance and mouthfeel of shredded pork or chicken. There are many products in between. Our expertise is in meat analogs made by twin-screw extrusion with high moisture content, also called high moisture extrusion cooking (HMEC). The twin-screw extruder processes plant proteins such as pea, lupin, soy or gluten at a moisture level over 50%. These plant proteins may also be blended with animal proteins. The first step is to debundle the proteins and create a gel. Then, in a precisely thermal-controlled die, the mix is cooled, leading to the formation of fibers created by hydrogen bonds between the proteins. The final product has a texture that mimics meat muscle.

M+P: What variables must a formulator consider?

Maller: When designing the base product, you need to take into account some limitations in terms of protein content, as it needs to be more than 50% of the dry base. Other ingredients, including fat and salt need to be added. Some minor ingredients, such as starch and texturing agents, can be added to facilitate the processing of the protein mix and add other characteristics. Adjusting and fine-tuning these elements is essential and based on an understanding of the process and ingredients.

Julie Prost: Like processing standard meat and poultry into consumer-ready products, developing and formulating meat and poultry analogs involves different process steps. The extruder is certainly crucial because it produces the fibrous meat-like texture. Yet, to create the similar mouthfeel experience to meat for the final product, it is also important to consider the downstream equipment and processes, for example, marinating, shredding and forming. This will influence the extrusion process. An extruder is an extremely versatile tool where you have many options that can impact the characteristics of the product depending on the thermal and mechanical energies provided.

M+P: What meat and poultry formats are the easiest to replicate?

Maller: Traditionally it has been easier to imitate white meat, such as poultry or pork. The juicy aspect of red meat had remained a challenge. But much research and development has being done in this area. We’ve learned how to combine extruded fibers with other ingredients in order to make the finished dish with the characteristics that will entice consumers. These include both solid and liquid ingredients that are mixed with the fibers, but also additional brining, coloring, flavoring, cooking, steaming, cutting, shredding, etc.

M+P: What are the greatest challenges when formulating analogs?

Maller: Plant fibers have many different attributes and it is important to have a good understanding of how they react in various processing scenarios. We can compensate for or alter these attributes through proper utilization of the extrusion platform. This includes applying the correct shear, temperature profile, etc., and in some instances, injecting liquid ingredients into the extruder barrel at different stages of the cooking and fibration process. Honestly, there is a bit of trial and error, and experience is a key factor in making products that meet consumer expectations.

Prost: The choice of the ingredients in the formulation is crucial. As mentioned, the protein content must be at least 50% of the dry mix. The functionalities provided by the protein are directly related to their source, their internal composition, e.g., amino-acid content, and the process that has been used to concentrate or isolate the protein. After choosing those ingredients, the best way is to test them through an extruder to see their ability to create the expected fibration with the right product texture, aspect and taste.