## 1 Introduction  
During the processing of raw materials cultivated in agriculture, large quantities of by-products and waste are generated, which are still used inefficiently. Agricultural waste and by-products from the processing of plant raw material are widely utilized in animal feed production, while biomass residues are used for bioenergy production. However, due to the high content of valuable compounds in plant-based waste, their application in the production of higher-value food products or in the pharmaceutical and cosmetics industries would be both important and economically beneficial [1]. Biologically valuable compounds can be extracted and recovered from plant-derived waste and processing by-products, transforming them into food ingredients, supplements, and/or functional food products [2; 3; 4].  
Berry processing by-products are rich in biologically active components such as proteins and amino acids, dietary fibers and oligosaccharides, phenolic compounds, lipids and fatty acids, and vitamins [5]. With appropriate processing, these compounds can be used to develop products that not only possess improved functional properties but also provide greater health benefits [6].  
Sea buckthorn (_Hippocampe humnoides_ L.) berries are rarely consumed fresh due to their sour and stringent taste; therefore, they are typically processed and used as ingredients in beverages, juices, jams, candies, and other products. These berries are rich in antioxidants, polyphenols, unsaturated fatty acids, tocopherols, and phytosterols [7; 8; 9]. To date, most of the research has focused on the analysis of polyphenic extracts, with particular emphasis on the composition and bioactivity of their lipophilic and hydrophilic fractions [9; 10; 11]. However, the dietary fibers present in sea buckthorn pomace (SBP) may also serve as potential components in functional products for the food, pharmaceutical, and cosmetic industries providing low-cost raw materials for value-added products [12]. Comprehensive and systematic data on the composition of dietary fibers in SBP are lacking. For effective industrial application of these pomace residues, it is important to understand their technological properties. Literature data on the technological characteristics of SBP, particularly in relation to emulsion stabilization, are also scarce.  
When assessing the health impact of dietary fibers, an important parameter is the ratio of SDF to IDF and the content of oligosaccharides as potential prebiotics. The recommended ratio of soluble to insoluble fiber is between 1:2 and 1:3, whereas most berry pomaces contain significantly higher amounts of insoluble fiber [13; 14]. To increase the levels of soluble dietary fiber and oligosaccharides in berry pomace and to improve their technological functionality, various modification methods can be applied, including enzymatic hydrolysis [15; 16], and others. No information has been found on the effects of supercritical CO\({}_{2}\) extraction (SFE-CO\({}_{2}\)) on the fiber and technological properties of SBP, and data on the effects of enzymatic hydrolysis are limited. By applying modern technologies, it is possible to identify the most suitable method for modifying SBP to enhance its value and potential applications in food. The aim of this study was to evaluate the effects of modification methods-supercritical CO\({}_{2}\) extraction, and enzymatic hydrolysis--on the composition and technological properties of sea buckthorn (_Hippocampe humnoides_ L.) pomace.