## 3 Results  
### Rheological Properties of Dough  
The values of apparent viscosity as a function of shear rate, as well as the consistency coefficient and flow index, are shown in Figure 1. All of the tested raw doughs for vegan muffins exhibited shear thinning behavior, characterized by high viscosity. This finding aligns with previous studies by many authors [14; 15; 16; 17]. High dough viscosity can favorably influence baking porosity and texture. Viscosity is a factor that controls the final porosity of the baked product due to its effect on the incorporation and movement of gas bubbles. Our research shows that the higher the viscosity of the dough (Figure 1a), the more pores and larger porosity the muffins had (Table 3). On the other hand, the pores had a smaller structure thickness, and the muffin texture was very soft and delicate (Table 4). The rate at which gas bubbles rise under buoyant force is inversely proportional to viscosity. Increased dough viscosity helps retain gas bubbles within the dough, contributing to greater stability throughout the baking process [14]. Our observations, however, show that too high a dough viscosity is not desirable; it creates a large number of pores but lower structure thickness, and this does not favor the texture. Within the studied range of shear rates (1-100 s\({}^{-1}\)), the Ostwald-de Waele power equation provided a good fit (r\({}^{2}\) ranging from 0.996 to 0.999) to describe the relationship. The consistency coefficient (K) of the dough made with wheat flour (CW) was 58.3 Pa-s\({}^{n}\), significantly lower than that of the dough made with a mixture of spelt and wheat flour (SW), which had a K value of 74.7 Pa-s\({}^{n}\) (Figure 1). The addition of 1.5% microalgae (CWa1.5) resulted in an approximately 16% increase in the consistency coefficient compared to the CW sample. Similarly, the doughs based on the mixture of spelt and wheat flours with 1 and 1.5% microalgae additions (SWa1.0 and SWa1.5) exhibited significantly higher K values compared to the microalgae-free dough (SW), with increases of 25 and 37%, respectively. The flow index (n) was lower in the dough containing spelt flour, indicating higher viscosity compared to the dough made with wheat flour (Figure 1). Several studieshave demonstrated that dough viscosity is influenced by the type and quantity of ingredients used [14,15]. The higher fiber content in spelt flour may have contributed to increased water binding and subsequently led to a higher consistency coefficient and a lower flow index. Additionally, the microalgae, known for their gelling properties [2,6], likely enhanced the dough structure when combined with spelt flour, resulting in higher K values and lower n values. The rheological studies conducted on raw doughs provide valuable insights into the relationship between rheological parameters and dough composition and structure. Determining the ratio between elastic and viscous characteristics of the dough allows pastry and baking technologists to effectively model dough properties and achieve optimal results during reformulation and new product development [14,15,17]. Figure 2 presents the mechanical spectra of the raw doughs. All tested doughs exhibited elastic characteristics, with an increase in the values of the elastic modulus (G\({}^{\prime}\)) and viscous modulus (G\({}^{\prime\prime}\)) as the sweep frequency increased. They displayed the typical behavior of soft gels, with G\({}^{\prime}\) values higher than G\({}^{\prime\prime}\). The tg\(\delta\) values, representing the loss angle, were lower than unity for all samples, indicating the weakly fluid nature of the doughs tested. When formulating the dough, the inclusion of 50% whole-grain spelt flour (sample SW) resulted in a decrease in both G\({}^{\prime}\) and G\({}^{\prime\prime}\) compared to the dough based on wheat flour (CW). This outcome aligns with expectations based on the available literature. Spelt flour contains significantly more fiber, which may lead to damage to the gluten network [17].