## 3 Results and Discussion  
Wild edible fruits show rich biodiversity. They are harvested without commercial cultivation, making them a valuable source of bioactive compounds, yet the compound content may differ in various fruits. The chemical properties of the fruits are an important characteristic that determines how a given variety will be used [24]. This study demonstrated that the dry matter of VO fruits amounts to 17.3% \(\pm\) 0.7 (Table 1). A similar amount of 16.9% was observed in the study by [PERSON] et al. [4]. The harvest period has an influence on the dry matter content and in the winter the amounts are higher [25]. The extracted content is one of the basic parameters that assess the suitability of the raw material for food processing. VO fruit extract determined, with the use of the refractometric method, was 13% \(\pm\) 0.53. VO fruits have a lower extract content as compared to other fruits, e.g., apples (conventional cultivation), 11.7-16.1% [26]; comrelian cherry, 13.8-19.85% [27]; blueberry, 15.0-15.3% [28]. One of the important quality characteristics of these fruits is their acidity and the sugar-acid ratio. Acidity depends on the degree of ripeness, climatic conditions, and varietal characteristics [27]. Viburnum opulus acidity content amounts to 1.78 g/100 g. In the study conducted by [PERSON] et al. [4], this content was higher--3.2 g/100 g. The \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Unit** & **Guelder Rose Fruit** \\ \hline Dry matter & 17.3 \(\pm\) 0.7 \\ * Extract & 13 \(\pm\) 0.53 \\ * Titratable acidity & 1.78 \(\pm\) 0.48 \\ * Pectin & 1.10 \(\pm\) 0.97 \\ * Vitamin C & mg/100 g & 47.79 \(\pm\) 1.02 \\ * Sugar (fructose) & g/100 g & 6.85 \(\pm\) 0.67 \\ \hline \hline \end{tabular} Values expressed as mean \(\pm\) standard deviation, (n = 3), * Results are expressed as g/100 g of dry mass (DM).  
\end{table} 
Table 1: The values of dry matter, extract, titratable acidity, pectin, vitamin C and sugar in guelder rose fruit. taste of the fruits largely depends on the extract-acidity ratio [27]. The higher the ratio, the greater the acceptance by consumers. According to the obtained results, the Viburnumic opulus' ratio is 7.3. In other fruits this ratio is higher, e.g., in apples, from 20.64 to 21.6 [26]; comelian cherry fruits, from 3.0 to 9.2 [27]; plums, 9.27 [28]; strawberries, from 9.875 to 11.9 [29]. However, in blackcurrants, the ratio is 4.9 [30], which is lower than in VO fruits. The presence of pectin in fruits is important, and depending on the direction of development, may be desirable or undesirable. For example, in the production of juices and beverages, these compounds make the process less efficient and decrease the clarity of the products, in the case of cloudy products, they stabilize their turbidity, while in the case of gelled products, such as purees or jams, they give them the right texture. The raw materials rich in pectin compounds include currants, blackberries, raspberries, and apples [27]. The studied raw material was characterized by a high pectin content of 1.10% \(\pm\) 0.97. Guelder rose is suitable for preparing jam and marmalade. In early autumn, the fruit reaches consumable maturity and is rich in pectin [25]. Guelder rose fruits can be classified as valuable sources of vitamin C. Our study revealed that the amount of ascorbic acid (vitamin C) in dried fruits was 47.79 \(\pm\) 1.02 mg/100 g DM. These values were higher in comparison to other results in fresh fruits: 12.4-41.4 mg/100 g [4] or 27-39 mg/100 g [5]. The sugar content indicates the taste and determines the suitability of the raw material for processing. In the fruits, this content (only fructose was identified) was 6.85 g/100 g \(\pm\) 0.67. This amount was lower than the one demonstrated in the study conducted by [PERSON] et al. [4]. They revealed an amount of 7.6 g/100 g of reducing sugar in fresh fruits. This effect could be due to the period of storage at a low temperature during freezing. Under this study, VO fruits were also tested for ABTS, FRAP and TPC (Table 2).