## 1 Introduction  
Bread is widely consumed around the world, therefore, plays a significant role in human nutrition [1]. Due to the growing awareness of health problems, the baking industry is trying to provide functional food with pro-health properties [2]. Studies on the nutritional value of bread are aimed at increasing the content of macronutrients (carbohydrates, proteins, fats, and dietary fiber), micronutrients (minerals and vitamins), and health-promoting components [2, 3]. Attention is also paid to the sensory acceptability and shelf life of enriched products [4].  
An example of the enrichment of baked goods with health-promoting ingredients can be the use of plant proteins, particularly proteins from legumes. [PERSON] et al. [5] developed a high-protein bread recipe in which wheat flour was partially replaced with ingredientsderived from broad beans and carob. [PERSON] et al. [4], on the other hand, used the addition of soy flour and cassava to wheat flour, and [PERSON] and [PERSON] [6] used the addition of sprouted red kidney beans. [PERSON] et al. [7] obtained good sensory acceptance for wheat bread enriched with yogurt and cottage cheese.  
The addition of kale (_Brassica elencea_ L. var. _accephala_) to bread may be an interesting alternative for the development of innovative bakery foods. Kale is a biennial vegetable belonging to the _Brassicaaceae_ family, which has been cultivated for centuries in many countries. It is consumed especially in the US, Japan, and the Mediterranean region [8]. Kale has been extensively studied for its nutritional value [9; 10; 11] attributed to the high content of bioactive components, including phenolic compounds, glucosinolates, chlorophylls, and carotenoids [12; 13]. Kale leaves also contain quite a lot of minerals (Ca, K, Fe, Mg), vitamins (C, E), and unsaturated fatty acids [14; 15]. It should also be noted that kale has a relatively high protein content. [PERSON] [16] showed that it is a high-value protein containing significant amounts of glutamic acid, aspartic acid, proline, and leucine. Kale is also a very good source of dietary fiber, the consumption of which reduces the risk of cancer and cardiovascular diseases [17; 18; 19].  
The consumption of kale has been shown to have antioxidant, anti-carcinogenic, and protective effects on the cardiovascular system and gastrointestinal tract [20; 21; 22]. Kale has been found to protect against high-fat diet (HFD)-induced dysfunction through mechanisms including lipid metabolism, endotoxemia, and inflammation [23]. Due to its health-promoting properties, it is used, among others, for the production of frozen foods, chips, drinks (smoothies), and vegetable pastes, but also in the production of dietary supplements or in the cosmetics industry. Thus, the use of this raw material in Thus, the use of this vegetable in bread baking can fit into the current nutritional trend related to the enrichment of products with ingredients with high health-promoting properties. For example, [PERSON] et al. [24] enriched wheat bread in kale microgreens and fresh young kale leaves.  
Therefore, the aim of our study was to investigate the effect of the addition of fully ripe kale leaves, in the form of lyophilize, on the wheat dough, the quality, and the shelf-life of the resulting bread.