## 1 Introduction  
Bread is a staple food consumed by people across the world. According to World Health Organization (WHO) data, the per capita consumption of bread is estimated at about 250 g per day [1]. It is consumed at a higher ratio, especially in the cereal-based diet of societies in developing countries. Its nutritional value depends on the raw material composition and production technology. Bread is mainly a source of carbohydrates (70-80% d.m. ), although it also contains proteins (10-14% d.m. ), minerals (0.5-0.8% d.m. ), and fats (0.7-1.35% d. m.). The dietary fiber content in bread is rather low, around 2-3% [2]. Due to its universal character and volume of consumption, it is possible to increase the nutritional value of bread through the use of appropriate additives for its production, including non-traditional raw materials. Flex cake is a waste product after oil pressing, and similarly to lupine seeds, it is usually used as a feed component. However, these materials may become valuable food ingredients. First of all, the chemical composition of both raw materials is interesting. They are characterized by a low content of digestible carbohydrates, high content of protein, and dietary fiber [3; 4; 5]. The nutritional composition of these raw materials makes them a valuable addition that can modify traditional wheat bread, changing the glycemic load and increasing the content of protein and dietary fiber. Flex cake contains \(\sim\)35% d.m. of protein, \(\sim\)33% d. m. of dietary fiber, and still linen oil (\(\sim\)12% d.m. ), while the content of available sugar (\(\sim\)8% d.m.) is lower in comparison to wheat [3]. Apart from interesting macronutrients, it contains various antioxidants and lignans, not extracted together with linseed oil. These compounds are effective against diabetes, cancer, and cardiovascular disease, and they are also recommended for permenopausal women [3; 6]. Lupine seeds are rich in protein (up to 39% d.m. ), with a protein content four times higher than in wheat grains. They also have one of the highest fiber concentrations (32% d.m.) and contain a very small content of starch. Lupine does not contain cholesterol or gluten, or gastric irritants; modern sweet varieties are free of alkaloids. Corresponding to its low starch and high dietary fiber contents, it has a very low glycemic index (GI) and is recommended as an element of diet for diabetics or people who want to lose weight, lower the level of cholesterol and triglycerides in the blood and regulate blood pressure [7; 8; 9]. Unfortunately, these additives may change the physicochemical properties of bread. They may interfere with the formation of the gluten network in bread dough. This effect can be eliminated by the fermentation process, which improves the functional properties of protein and dietary fiber fractions [10]. Currently, in the market of bakery products, a trend of limiting the consumption of bread and simultaneously the growing interest of consumers in bread with increased pro-healthy values is observed. Due to the constantly recorded increase in the incidence of civilization diseases, the application of raw materials with proven anti-diabetic and hypertension-lowering properties will increase bread attractiveness and desirability. The innovativeness of the conducted research relies on the use of non-traditional raw materials such as flax cake (instead of whole flax seeds) and lupine flour (not used in baking) as an addition to bread production. In order to minimize the negative impact of flax cake and lupine flour on the characteristics of bread, it is intended to ferment them. This process should positively affect not only the physicochemical quality of the bread but also increase the bioavailability of the nutrients from these additives. Therefore, the aim of the presented study was to produce bread with modified nutrition quality by the addition of non-fermented and fermented flax cake and lupine flour.