## 3 Results and Discussion
### Caffeine and Chlorogenic Acid in Cold Brew Samples
[10]--the concentration of extracted bioactive compounds reaches an optimum value after a certain time, and prolongation of this time may even result in a decrease in the content of active components. The time of the 24 h trial, regardless of the conditions of the extraction environment, had a negative effect on the amount of the tested compound. The experiment carried out, reflecting different technological processes, shows that with increasing extraction time the content of chlorogenic acid decreases in all samples. Results for profile C are two times lower than profile A. According to [PERSON] and [PERSON] [11], high losses of chlorogenic acids are linked to their sensitivity to oxidation, mainly based on the activity of polyphenol oxidase (PPO) found in grains. In the presence of oxygen in the air, this enzyme catalyzes the transformation of phenolic compounds. During this process, quinones are formed and it cannot be ruled out that they play a role in the loss of coffee beverage quality [12]. Figure 1: Cold brew coffee means values of chlorogenic acid concentration in the coffee roasting profile \(\times\) extraction temperature matrix. Homogeneous groups (\(p<0.05\)) are marked with the same letters. Final roasting temperatures: A 210 \({}^{\circ}\)C, B 220 \({}^{\circ}\)C and C 230 \({}^{\circ}\)C were roasting profiles. [PERSON] and [PERSON] [3] determined the content of caffeoylquinic acid along with its derivatives in six cold brew samples prepared from different types of coffee. One coffee from Brazil was also used in the study. The total amount of phenolic acid and its isomers was 2201 mg/L, and the concentration of the main compound 5-CQA (5-caffeoylquinic acid) was 1124 mg/L. The results presented here differ from those reported by [PERSON] and [PERSON], which may be due to the use of different analytical techniques and the amount of compounds tested. After calculating an average 5-CQA content of their six samples, the concentration of the compound is estimated to be 1012 mg/L. This indicates a significant approximation of the given value to the extracts prepared under the first variant of time and temperature, and the difference between the highest level of chlorogenic acid for the sample from profile A is 16 mg/L relative to an average 5-CQA. In another study, the authors [PERSON] and [PERSON] [13] compared the chlorogenic acid content of coffee depending on the degree of roasting and grinding of coffee prepared for cold brew. They assigned the lowest determined value after 24 h of extraction to Dark-Coarse 360 mg/L coffee and the highest to Medium-Coarse 520 mg/L. After testing, all the results with the lowest chlorogenic acid concentration were found to be between 445 mg/L and 494 mg/L. Figures 3 and 4 below show that the caffeine content ranged from 430 to 631 mg/L. Another study analyzed the caffeine content of 20 different coffees bought in coffee shops in the United States. The amount of caffeine in the brews corresponded to 320 to 470 mg/L, and the caffeine content in coffee of the same type bought in the same shop six times in different portions corresponded to 540 to 1180 mg /L [14]. In the case of caffeine, the results indicate that the type of bean to obtain cold brew coffee with the highest concentration of this compound is coffee whose final roasting temperature reached 220 \({}^{\circ}\)C. For coffee B, the values were 603 to 631 in mg/L. It can be assumed that, under the influence of high temperature, part of the alkaloid was released from the cellular matrix structure of the bean under acid degradation, which favorably increased the concentration of this compound in the final extracts with respect to profile A. In contrast, a decrease in caffeine content was observed for profile C extracts. It seems that caffeine is easier to extract from dark roasted coffee, but in the raw material obtained close to its melting point [15], there is clearly a reduced strength of its extraction in the prepared solution.