## 1 Introduction  
Nowadays, consumers are more and more concerned about the nutritional value of food. They are changing their dietary preferences and incorporating the least-processed products, rich in valuable bioactive compounds, into their diets. This is leading to an increase in demand for fruit and fruit preserves, among other things, and consequently, to an increase in waste. By-products are a problem for production facilities and a threat to the environment [1, 2, 3]. The food industry produces millions of tons of waste worldwide, which can be divided into two main categories: plant-derived wastes and animal-derived wastes, which can be used as a source of valuable ingredients [4]. Fruit processing wastes belonging to one of four subcategories of plan-derived wastes have great technological potential. They can be used as low-cost functional ingredients in food, pharmaceuticals, cosmetics, dietary supplements, and other products [1, 4]. Biologically active compounds are often found in these wastes. For example, chokeberries are a source of phenols, about 25% of which are anthocyanins [5]. Like most phenolic compounds, anthocyanins are found in the peel, which is accumulated in the pomace [6, 7]. Before entering the final product, the wet pomace of chokeberry is dried, which increases microbiological safety and facilitates storage and transport [1]. The management of post-production waste, rich in bioactive compounds, is in line with the concept of sustainability and the circular economy. It makes it possible to obtain health-promoting and innovative products while contributing to the reduction of waste [4; 8]. Chokeberry (_Aronia melanocarpa_ L.) is a globally cultivated plant [9]. Its fruits are a source of anthocyanins, flavonoids, other phenolic compounds, vitamins, and minerals [10]. Therefore, consumption of chokeberries has a positive effect on human health. It has been shown to have anti-cancer effects (e.g., colorectal cancer, certain types of breast cancer, and colon cancer) [11]. It can neutralize the formation and aggravation of side effects of anti-cancer drugs. In addition, it can support the treatment of hypertension, dyslipidemia, disorders of glucose metabolism, obesity, inflammation, and thrombosis. Due to its sour taste, chokeberry is rarely consumed raw and is mostly processed (i.e., in juices, wines, jams, syrups, and tinctures). It is also used as a source of fiber and, when dried, in teas [12; 13; 14]. The leader in chokeberry production is Poland, where it is mainly processed into juice. Its production generates 10,000 tons of chokeberry pomace per year [15]. Such a large amount of post-production waste poses an environmental challenge for sustainable processing. In 100 g of wet pomace, there are 60 g of dietary fiber and 5 g of other bioactive substances, such as phenolics [9; 16]. Chokeberries have gained popularity due to their high content of polyphenic compounds compared to other plant products. Contents of total polyphenols in pomace from chokeberry is 105.8 mg/g d.w. In contrast, other foodstuffs exhibit lower levels of these beneficial nutrients. For example, plum (3.77 mg/g f.w. ), sweet cherry (2.74 mg/g f.w. ), apple (1.36 mg/g f.w. ), blackberry (2.5 as gallic acid equivalents), raspberry (1.26 as gallic acid equivalents), and lingonberry (2.49 as gallic acid equivalents) display lower concentrations of these nutrients [9]. Research is being conducted to increase the use of chokeberry pomace in a variety of products such as breakfast cereals, bakery products, meat product additives, feed additives, coating, and packaging ingredients [17; 18]. Bakery products are popular snack foods with high consumer acceptance [19]. In their composition, fat, which is a source of saturated fatty acids and sometimes trans isomers, and sugar are present in large amounts [20; 21]. Due to the low nutritional value of classic bakery products, many researchers are developing new, healthier versions of existing products [1; 22; 23; 24; 25; 26; 27].