3.7 Meat Substitutes
There is a broad range of vegetarian meat substitutes on the market. Meanwhile major supermarket chains in Germany offer a selection of products such as vegetarian sausages, spread, or burgers. The vegan variants are usually based on soy or wheat protein or, in case of burgers and patties, on grain, while vegetarian variants often contain egg protein. Meat substitutes are designed to equal the animal alternatives in taste and texture, among them convenience products such as vegetarian Bolognese or Gulasch or “crunchy” sticks. The nutrient composition of the vegetarian products varies to a great extent similar to the correspondent meat products. Products with a low to moderate fat content should be preferred, and the source of fat (plant or animal) should be considered. An advantage of the plant-based substitutes is the usually low amount of saturated fat. In addition, they may contribute to fiber intake depending on the ingredients. Burgers and patties based on grains have a high content of carbohydrates and thus may substitute for both meat and side dishes like rice or pasta in a traditional meal.
In contrast to dairy substitutes, meat substitutes are generally not fortified. Hence, these vegetarian alternatives provide no compensation for vitamin B12 from animal products. Like many common meat products, the vegetarian alternatives often contain high amounts of salt (about 2 g/100 g). Furthermore, convenience products often contain additives such as flavoring agents or preservatives. Therefore basic products like soy granules, plain tofu, or seitan should be preferred.
Ute Alexy, … Mathilde Kersting, in Vegetarian and Plant-Based Diets in Health and Disease Prevention, 2017
R. Osen, U. Schweiggert-Weisz, in Reference Module in Food Science, 2016
Control of Fiber Formation
One major characteristic of high-moisture meat substitutes is their unique fibrous structure which gives the products a meatlike appearance. By variation of the process conditions, it is possible to generate products with the appearance of whole muscle meat that resembles, e.g., chicken or beef. The fiber length, thickness, or fiber orientation can be controlled and requires the unique combination of extrusion operation conditions. Based on the system analytics model introduced by Meuser and Van Lengerich (1984) that describes the ‘black-box’ extrusion process, Figure 5 illustrates the input process variables and the resulting parameters inside the extruder and the cooling die, all which contribute to the final fiber formation of plant proteins.
Figure 5. Input variables and dependent parameters during high-moisture extrusion cooking.
Adapted from Camire, M.E., 1998. Chemical changes during extrusion cooking – recent advances. In: Process-Induced Chemical Changes in Food, vol. 434, pp. 109–121 with permission.
The control of fiber formation requires specific physicochemical reactions of the protein mass which depend on the system parameters inside the extruder and the cooling die that in turn are the result of the variety of process variables.
Based on the fundamental work of Noguchi (1990) and Cheftel et al. (1992), several studies were published on the effect of extrusion process parameters on the structural and sensory properties of high-moisture extrudates using soy protein. Moisture content is an important factor on the overall product texture. Lower moisture content resulted in higher die pressure, harder texture, and lower total protein solubility and the products were tougher, chewier, and more cohesive (Lin et al., 2000, 2002). Furthermore, the cooking temperature highly affects the texture properties (Noguchi, 1990; Thiebaud et al., 1996; Chen et al., 2010b; Osen et al., 2014). Figure 6 shows the influence of cooking temperature on the texture properties of pea protein isolates extruded at 55% moisture.
Figure 6. Cutting strength of high-moisture extrudates made of pea protein isolate as a function of cooking temperature at 55% moisture content (w/w).