## 4 Results and Discussion
### Analysis of Organic Compound Concentrations  
Phenolic acids and other organic compounds were quantified using the RP-HPLC technique. The concentrations of organic compounds in the analyzed yerba mate products were determined after water and methanol extraction. An exemplary chromatogram of the analyzed sample of yerba mate products is shown in Figure 1. The obtained extracts of the tested yerba mate products (P-1-P-10) were analyzed. The chromatograms for samples P-2-P-10 revealed the presence of neochlorogenic acid, chlorogenic acid, 4-feruloylquinic acid, caffeic acid, isochlorogenic acid, caffeine, rutoside, and astragalin. However, the chromatograms for sample P-1, in both water and methanol extracts, did not show substances characteristic of yerba mate; only protocatechuic acid and caffeine were identified. The contents of the following antioxidant compounds were assessed: neochlorogenic acid, chlorogenic acid, 4-feruloylquinic acid, caffeic acid, and isochlorogenic acid. The findings were calculated per gram of dry weight and are presented in Tables 3 and 4. The structural formulas of the given compounds are shown in Figure 2. For the P-1 product, a chromatogram was obtained that lacked the phenolic constituents typically found in yerba mate but exhibited a distinct peak corresponding to an identified compound--protocatechuic acid. In the analysis, the highest content of chlorogenic acid was detected in both methanol (14.7412 mg/g d.w) and water (8.3120 mg/g d.w) extracts in product P-4. The caffeic acid content ranged from 0.1491 mg/g d.w. and 0.0760 mg/g in methanol and water extracts to 1.7938 mg/g d.w. and 0.4892 mg/g d.w. in methanol and water extracts. The neochlorogenic acid content ranged from 2.6869 to 23.9750 mg/g d.w. in ethanol extracts and from 0.4529 to 10.2299 mg/g d.w. in water extracts. The composition of antioxidant compounds in methanol-extracted samples differs from that of water extracts. In general, the content of chlorogenic acids was significantly higher in methanol extracts compared to water extracts. Phenolic compounds in yerba mate exhibit antioxidant properties, contribute to overall health, and may reduce the risk of chronic diseases [44]. Phenolic compounds found in yerba mate, such as chlorogenic acids, could potentially serve as prebiotics. Chlorogenic acids may specifically influence the intestinal microflora, particularly the ratio of _Bacteroides_ to _Frimicutes_. An imbalance in these two types of bacteria has been associated with the development of insulin resistance and obesity. Therefore, the consumption of yerba mate could potentially have beneficial effects on gut health and overall metabolic function [45,46]. Although there is no universally defined daily requirement for phenolic compounds, incorporating foods rich in these bioactive molecules contributes to health. Yerba mate, with its abundant phenolic content, can be a valuable addition to a balanced diet. For specific recommendations, the Academy of Nutrition and Dietetics suggests 400-600 mg of flavanols per day to support cardiometabolic health, but individual needs may vary, and a diverse diet ensures a broader intake of these beneficial compounds [47]. Additionally, the concentration of the following compounds was analyzed: caffeine, rutoside, and astragalin. The content of these compounds in P-1-P-10 products is presented in Table 5. The differences in the content of the tested compounds in ethanol and water extracts are additionally illustrated in Figure 3. Yerba mate is perceived as an energizing or relaxing drink, the consumption of which is similar to tea and infusions; yet there is limited awareness about its antioxidant properties [48]. Caffeine plays a pivotal role in conferring stimulant properties; therefore, the caffeine content was also determined. The content of this purine alkaloid ranges from 0.0278 to 1.1399 mg/g d.w. in water extracts and from 0.1963 to 3.4059 mg/g d.w. in methanol extracts.