# Designing the Quality Characteristics of Berry Processing Byproducts Using Fermentation
## 1 Introduction  
The valorization of byproducts generated during fruit processing is a consistently growing trend observed in both economic practice and the world of science. These byproducts pose serious problems both economically and ecologically. Currently, these byproducts are often disposed of in landfills, composting plants, or fed into the fermentation process of biogas plants. However, these methods contribute to greenhouse emissions and release waste into the environment. In addition, they result in losses of valuable biomass, nutrients, and economic resources. Therefore, the reuse of these byproducts can lead to both economic and ecological benefits. Activities related to reduction, recycling, and reuse are part of the global trend associated with the concepts of sustainable development and consumption [1; 2; 3; 4; 5]. Chokeberry [6; 7], blackcurrent [8; 9], raspberry [10; 11], and strawberry [12; 13] represent fruits with a high content of polyphenonic compounds. Their immunity-strengthening,anti-inflammatory, and antioxidant properties have previously been reported [14; 15; 16; 17]. These fruits are an important element of the human diet; most of them, however, are sent for processing in order to obtain juices, nectars, and musts, as well as other products. During fruit juice production, between 20% and 60% of the weight of raw pomace materials is produced [18; 19], which can be used for fertilizers, feed, energy, and cosmetics, among other purposes [20; 21; 22; 23; 24]. The byproducts of fruit processing, such as chokeberries, blackcurrants, raspberries, and strawberries, similar to the raw materials themselves, are rich in nutritionally valuable ingredients. These include dietary fiber, essential unsaturated fatty acids, exogenous amino acids, dyes, substances with antioxidant properties, and sterols [25; 26; 27; 28; 29; 30]. Therefore, they can be a valuable secondary raw material in the food industry due to their use in production, including innovative additives that enrich food products or as ingredients in dietary supplements [31]. Research has shown that raspberry pomace represents a valuable source of fiber and bioactive substances in gluten-free bread [32], waffles [33], and confectionery products [34]. [PERSON] et al. [35] found that adding raspberry pomace extract to fruit pures resulted in an almost threefold increase in the total content of polyphenols, thus improving the functional properties of the products. In another study, the addition of blackcurrant and strawberry pomace to bread increased the antioxidant potential compared to the control bread [36; 37]. According to research by [PERSON] et al. [38], supplementation with blackcurrant seed oil lowers LDL cholesterol levels more effectively than supplementation with fish oil. Chokeberry pomace, a source of bioactive compounds, especially anthocyanins, is a valuable secondary raw material used to produce dark anthocyanin dyes [39]. Chitosan films with chokeberry pomace extracts showed higher antioxidant properties than the control sample. Chokeberry pomace extracts strengthened the barrier properties of chitosan films against both UV-Vis light and water vapor, while also reducing their oxygen permeability [40]. Chokeberry pomace has been used as a functional ingredient in preserves [41; 42]. According to [PERSON], [PERSON], [PERSON], and [PERSON] [43], blueberry pomace flour can be used to produce fermented drinks. It exhibits microbiological stability during storage and excellent technological properties, which allow it to be used to create new products. To date, producers and consumers have not sufficiently utilized the byproducts of berry processing as a source of natural bioactive substances with beneficial effects on the body, primarily due to the low acceptance of their taste. The appropriate processing of berry byproducts can alter their unfavorable organoleptic properties and increase their antioxidant potential.