## 1 Introduction  
Bread constitutes basic food worldwide. European consumers are increasingly demanding in terms of bread's quality, freshness, and nutritional and sensory properties. Sensory attributes and repeatable quality of bread affect the preferences of its consumers and decisions about its purchase [1, 2]. In recent years, many research studies have been conducted to improve the quality of bread and bakery products, both nutritionally and technologically (e.g., texture, moisture retention, and starch retrogradation rate). The decreasing salt or carbohydrate content or increasing protein content [3, 4] and dietary fiber (DF) [5] in bakery products were implemented. Cereal products contain high starch and low DF content. However, according to nutritional guidelines, consumers' DF intake is too low and should be increased [6, 7]. The high nutritional value of DF has been well-documented over the years as a preventive ingredient for certain diseases, including obesity, cardiovascular disorders, and high cholesterol levels [8, 9]. Moreover, it has been noticed that the availability of bread products with high levels of DF is low. Therefore, product variety should be expanded to fulfill the need for functional foods (also with DF) that will be well-recognized and valued by consumers [10, 11, 12]. The use of fiber-rich ingredients in the dough causes changes in water absorption and quality of the bread; e.g., a mixture of fibers (inulin and white oat fiber) causes a decrease in specific volume and an increase in hardness [13]; the use of \(\beta\)-glucan in bread increases the moisture and decreases the particular volume [14]; and pectin in a bread sample causes an increase in moisture and color changes [15]. There is a widespread belief that for bakery products, only whole-grain bread products could provide satisfactory sources of DF for humans. However, whole-grain flour is made by milling the grains only once with little heat treatment, which could lead to a high food safety risk [16]. Therefore, fortifying wheat flour with other bioactive substances, such as \(\beta\)-glucan, is more reasonable. Beta-glucans are soluble fibers that can be of cereal ((1\(\rightarrow\)3) (1\(\rightarrow\)4) \(\beta\)-D-glucan), fungal, and microbial origin ((1\(\rightarrow\)3)(1\(\rightarrow\)6) \(\beta\)-D-glucan) [17]. In particular, consuming food fortified with \(\beta\)-glucan may have positive health influences as \(\beta\)-glucan can decrease low-density cholesterol (LDL) levels, leading to a reduced risk of coronary heart disease and hypertension [18; 19]. Increasing DF (including \(\beta\)-glucan) content during bread making can deteriorate bread quality [20]. Beta-glucans are important molecules not only because of their nutritional properties but also because of their technological aspects, such as the rheological properties of dough and bread quality [21]. Texture is one of the most important factors influencing the perception of bread technological quality. Consumers often consider texture one of the most essential quality factors when they purchase food. Current methods available in the industry are mainly based on measuring the shear force, which is destructive. Therefore, it is necessary to develop novel strategies that could rapidly and easily estimate the texture properties of bread as influenced by factors such as porosity, which can otherwise be measured by traditional instrumental techniques such as textural profile analysis that are complicated, slow, and destructive. The pores in bread constitute a significant determiner of crumb texture development and, thus, are an important parameter for texture modeling [22]. Optimization studies can be carried out by using multivariate statistical methods. Response surface methodology (RSM) is an appropriate approach widely used to optimize food industry processes. This method helps optimize, design, develop, and improve processes where responses are affected by several variables.