## 3 Results and Discussion
### Caffeine and Chlorogenic Acid in Cold Brew Samples
Figure 2: Cold brew coffee means values of chlorogenic acid concentration in the coffee roasting profile \(\times\) extraction time 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. The results of the experiment conducted by [PERSON] and [PERSON] [16] show that the amount of caffeine depends on the brewing method. Higher water temperature causes faster diffusion of the alkaloid. Full extraction occurs only in water at 100 \({}^{\circ}\)C after 15 min. In the case of cold brew coffee, it has been noted that the full extraction of caffeine can also be achieved in water at room temperature--the time of contact between the coffee and the water is important. The degree of grinding can be an additional factor affecting the caffeine content of cold brew by accelerating its diffusion in the initial hours of extraction. It should be noted that in addition to the extraction method, the ratio of coffee to water is an important determining factor. Information on the caffeine content of cold brew beverages prepared with different ratios was presented by [PERSON] and [PERSON] [14]. For a ratio of 7 g of coffee per 100 mL of water and an extraction time of 12 h and a temperature of 10 \({}^{\circ}\)C, the authors report an average caffeine content of 523 mg/L. These data are similar to the average caffeine content of our conducted study. Moreover, the average reported caffeine content of coffee infusions obtained from different blends and different methods of cold brew preparation was much higher--close to 860 mg/L [14]. Although many studies have been conducted on hot coffee extraction, research on cold brewing is more limited and known laboratory techniques are applied in some studies today in order to understand the difference between them. [PERSON] et al., because of low total solids yield and long extraction times in cold brew coffee production, studied the process of optimization and found that caffeine concentration and yield were significantly influenced by vacuum cycles (accelerating extraction and increasing the content of, compounds in the final beverage). A maximum concentration of 10.02 g caffeine (per kilogram) was achieved through a combination of vacuum cycles and the duration of each cycle [17]. On the other hand [PERSON] et al. explored extraction with ultrasonication techniques to observe changes in the physicochemical properties of cold brewed coffee [18]. Their results led to significant increases in total soluble solids and most organic compounds. For example, caffeine reached a maximum level of 19.97 g and chlorogenic acid 2.1 g (per kilogram). The higher concentrations achieved by ultrasonication can be attributed to a better disruption of the cell walls, which also depends on the power and time of processing. Figure 3: Cold brew coffee mean values of caffeine 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. HPP treatment (High Pressure Processing) can also disrupt cell walls and other organelles in coffee, resulting in increased mass transfer rates of solutes during extraction. [PERSON] et al. [19] used HPP for medium, coarse and whole coffee beans and subjected them to 400 MPa for 10 min. They next allowed all samples to stand at 22 \({}^{\circ}\)C for 44 h for whole beans to achieve a comparable brew Total Dissolved Solids (TDS) as that from the ground coffee for 18 h extraction. Their results showed that infusions prepared from ground coffee beans had higher caffeine and chlorogenic acid concentration than those prepared from whole beans. This effect was demonstrated by the following levels: caffeine 0.48 g/L alone and 0.49 g/L with HPP, and chlorogenic acid 0.96 g/L alone and 1.01 g/L with HPP.