## 1 Introduction
### The Presence of Beneficial Antioxidants and Phenolics in Secondary Materials  
Irrational exploitation of by-products results in the loss of valuable bioactive compounds. Flavonoids, anthocyanins, other polyphenols, antioxidants, tocopherol, important fatty acids, carotenoids, and phytosterols are currently the most studied. For example, fruit-processing-related waste from the _Vaccinium_ species is one of the important renewable resources that can be widely applied to the development of health-promoting products. The fruits of the _Vaccinium_ species contain polyphenols, which play a significant role in the prevention of various chronic diseases, including precancerous conditions, inflammatory conditions, and other diseases [3; 37]. Pomaces of bilberries and blueberries are rich in anthocyanins, the bioactivity of which has already been proven by numerous studies. Therefore, such waste is a clear choice in the development of health-promoting products. Anthocyanins have well-known anti-inflammatory effects, but the literature also confirms that they can stimulate wound healing, protect the retina, manage intestinal health, and have antidiabetic, antioxidant, antibacterial, and other effects [38; 39; 40; 41; 42; 43]. The color properties of anthocyanins (alongside other coloring phytochemicals) may also have pharmaceutical purposes. Anthocyanins can be successfully used to color products as they are a natural alternative to synthetic regulated Red 40 dye [44; 45]. Hydroxcinnamic acid esters, especially chlorogenic acid, are also found in sufficient quantities in the herbal waste of the _Vaccinium_ species [3]. As about 20-30% of the biomass \begin{table}
\begin{tabular}{c} Food residues \\ Fruit pomace and cakes \\ Parts of the fruit (seeds and otherwise) \\ Leaves and parts of the plant remaining after crop collection \\ Residues of extracts \\ \end{tabular}
\end{table} 
Table 1: Main secondary herbal starting materials can be used for health-promoting products. of the fruit is transformed into pomace, which is rich in phenols and other active substances, secondary raw materials from species of this genus must be considered an exemplary source of phytochemical compounds suitable for industrial use [3; 22; 46; 47]. Significant concentrations of anthocyanins have also been observed in other dark-colored fruits and vegetables that can be processed in considerable amounts, such as blackberries, elderberries, purple sweet potatoes, and black carrots [45; 48; 49; 50]. Blackberry (_Rubus glaucus_ Benth.) fruits are commonly processed into concentrates, jams, and juices [51; 52]. About 20% of the fruit mass remains as blackberry pulp [52]. Violet-colored maize (_Zea mays_ L.) is also a viable alternative for the extraction of anthocyanins due to the high concentration of the aforementioned phytochemicals (4-10 g/kg) and the low costs of its storage and processing. It has been highlighted that most of the anthocyanin present in purple maize is concentrated in parts that can be easily separated, while the rest of the fruit can be used for food and the production of bioenergy [45]. High-quality biodegradable remnants remain in the wine industry. Waste originating from grapes is rich in phenols, including flavonoids and anthocyanins with high antioxidant potential [53]. Modified bio-processing methods can extract 71.9 g of grape seed oil and 322.8 g of polyphenols from the processing of 1.0 kg of dry grape marc [3; 53]. Apples are widely consumed worldwide. Some 20-30% of the total weight of apples consists of solid ingredients such as seeds, cake, and peel [13; 54]. Such waste contains bioactive phenolic compounds such as phloridzin, chlorogenic acid, quercetin glycosides, phlotreins, epicatechins, and procyanidin B2, all of which are promising compounds in the development of health-promoting products as they have antioxidative and other important properties [54; 55; 56]. Valuable phenolic compounds and valuable flavonoids also remain in the pulp of sugar cane (_Saccharum officiarum_ L.).