## 3 Results and Discussion
### Textural Properties of PBSs  
In traditional meat products, stromal and myofibrillar proteins are responsible for the firmness of the products, and the use of other proteins, including plant proteins, may result in a reduction in the firmness and hardness of the product [63]. Results obtained using the Warner-Bratzler shear test (presented in Table 3), often used to test the tenderness of meat products [64], showed that both the shear force and the total work of shearing are influenced by both the protein mixture and the added iron source used. PBS1/IS and PBS3/F were characterized by the highest hardness. At the same time, the same two analyzed variants of PBS showed the highest shearing work. However, when comparing the values of the analyzed texture parameters with the meat equivalent of the analyzed product, it can be observed that most of analyzed samples (except PBS1/IS) have comparable tenderness to finely comminuted frankfurters made in a traditional way [65]. [PERSON] et al. [66] noticed that replacing the meat in sausages with plant proteins worsened the mechanical properties, and the hardness of the products decreased. In our research, however, appropriately selected proteins and production technology resulted in the obtained products having properties similar to traditional meat products. Importantly, when comparing the appropriate protein mixtures with different iron sources, it was noticed that in the case of PBS1 and PBS2, the use of an inorganic iron source (/IS) significantly increased the hardness, while in PBS3 the variant enriched with organic iron (PBS3/F) was characterized by a higher hardness. It can therefore be assumed that the protein mixtures used interact with ingredients derived from sprouts and iron sulfate at the molecular level, resulting in the observed changes in the texture of the products. As literature data on the interaction of iron with milk proteins indicate, it is possible to create a complex structure between proteins and iron crystals. Moreover, fats can also be cross-linked, which significantly increases the hardness of the product [67; 68]. The proteins and fats used in the PBSs recipe could, therefore, be cross-linked in a similar way, but the affinity for structure formation depends on the type of proteins and the form of iron addition. In addition, divalent metals, including inorganic iron, can also stabilize and fill the voids between proteins, further hardening the structure [69]. It is worth noting that the tenderness of sausages also depends on other factors, such as the fat content or product temperature [70; 71]. Incorporating plant oils into food products is crucial for their rheological characteristics and structural integrity, as well as for imparting a distinctive flavor profile. Fat enhances the texture, taste, mouthfeel, overall sense of smoothness, and visual appeal of these products [72; 73]. Moreover, as literature data indicate, heating the sausage increases its tenderness [74]. Given the fact that hot dog sausages are eaten warm, the hardness of the products assessed by consumers will be lower. Therefore, it was decided to analyze both batters and finished products in terms of the changes in rheological and molecular properties using LF NMR.