## 1 Introduction  
A high dietary sodium intake may lead to cardiovascular, bone demineralization and cancer diseases [1, 2]. According to the American Heart Association, the cardiovascular diseases are the leading cause of mortality globally [3]. The close association between hypertension values and sodium intake is an important issue from a public health perspective. Nowadays, the World Health Organization (WHO) recommends to not exceed a sodium consumption of 5 g per day [4] and wants to reduce sodium intake up to 2 g Na/day [5]. In addition to the beneficial effects on health, sodium reduction also contributes to an annual decrease of medical expenditures [6]. Broad is considered worldwide to be an essential food for human nutrition. However, it might represent an important source of sodium intake. The increased consumption of bakery products increases the risk of diseases associated with sodium consumption [7, 8]. The sodium sources in bakery products are provided by ingredients such as sodium bicarbonate, a baking agent, widely used in baking and sodium chloride (NaCl) which is one of the main ingredients used in the bakery manufacturing process [9]. The sodium chloride additions in bakery recipe are very important from a technological point of view [10]. Its reduction may lead to negative effects on technological process of bakery products and the quality of the finished products [7; 11; 12; 13]. From the technological point of view, the sodium chloride addition increases dough strength and stability, its capacity to retain gases and, at low levels, yeast activity [7; 10]. To bakery products, NaCl increases the shelf-life, due to the inhibition effect on microbial growth, and it improves bread texture and its sensory properties [12; 13]. Due to the effect of sodium chloride on the technological process and the quality of the bakery products, its substitution in order to reduce the sodium content from the bakery products it is a problematic issue. Previous studies have shown that the potassium chloride (KCI) is the leading substitute for reducing sodium in bakery products [9; 10; 14; 15; 16]. Potassium chloride is a natural ingredient obtained from rock and sea salts with extraction methods similar to those of sodium chloride. The effect of potassium chloride consumption in the human diet is associated with a low risk of high blood pressure and other diseases associated with it, the effect being contrary to the intake of sodium chloride [17; 18]. It has a salty taste but with metallic and bitter after tastes when high levels are incorporated in bakery recipes [19]. Therefore, the complete replacement of sodium chloride in bakery products it is not recommended. Its use in food products may only be in combination with sodium chloride in order to obtain products of a high quality [10; 15]. Reducing sodium by replacing it with potassium chloride has to be done gradually because of its influence on technological process and quality of the bakery products [4]. The Response Surface Methodology (RSM) has been used in several food-related papers and applications. In the literature, some applications of RSM to flour, dough and bread, demonstrate its effectiveness. In particular, [PERSON] et al. (2020) developed optimization charts regarding the milling process of wheat and for flour characterization [20]. Moreover, [PERSON] et al. (2018) published predictive models of the rheological properties of doughs specifically developed with RSM [21]. The aim of this study was to analyze the effect of partial sodium chloride substitution with potassium chloride on the technological process of the bakery products. For this purpose, we used KCl and NaCl in different combinations by using response surface methodology (RSM) in order to analyze their effect on dough's rheological properties and to obtain their optimum formulation from the technological point of view.