## 3 Results and Discussion
In various studies, garlic differed significantly in the level of water activity, depending on the fermentation time and conditions (temperature and humidity) [36; 43]. Nevertheless, taking into account the results of other authors and the results of our own research, it can be concluded that the decrease in \(\mathrm{a_{w}}\) during the aging of garlic is relatively small, which is mainly related to high humidity present during heat treatment processes [36], and the obtained values of \(\mathrm{a_{w}}\) do not guarantee microbiological safety of the product thus obtained and cannot be used as an indicator of this durability [43]. Therefore, it is recommended to dry black garlic to a value of \(\mathrm{a_{w}}<0.85\) and seal it in barrier packaging. Black garlic is one of the foods with a relatively long shelf life due to the low pH resulting from the fermentation process. As can be seen from the data in Table 1, the tested garlic samples were characterized by a significant (\(p<0.05\)) differentiation in pH, which was on average \(6.42\pm 0.11\) for fresh garlic, and over 36% lower for fermented black garlic, amounting to an average of \(4.08\pm 0.08\). The obtained research results are similar to the results of other authors who showed that the pH of fresh garlic (6.13) drops due to the applied heat treatment (55 \({}^{\circ}\)C temperature, 80% humidity during 90 days) to approx. 4.0 [44]. [PERSON] et al. [43] showed that with the increase of the heat treatment time (90% humidity during 33 days), the pH decreased from \(5.93\pm 0.01\) for fresh garlic heads to \(3.49\pm 0.06\) for fermented garlic heads and from \(6.31\pm 0.07\) for fresh garlic cloves to \(3.52\pm 0.03\) for fermented garlic cloves, depending on the temperature. They also found statistically significant differences in the pH of fermented garlic depending on the temperature used in the aging process. Higher temperature resulted in lower pH. Other authors also found a significant decrease in the pH of raw garlic (6.42) heat treated at various temperatures (45 and 85 \({}^{\circ}\)C) for 45 days (5.00 and 3.05, respectively), suggesting that the decrease in pH is closely related to the processing temperature [36]. These authors also showed that heat treatment at 40 \({}^{\circ}\)C for 5 days causes pH to drop to 5.94, and at 80 \({}^{\circ}\)C to 4.09. These and other studies suggest that changes in garlic's pH depend on both the time and temperature of the fermentation process [36; 40; 43; 44; 64; 65]. The lowering of the pH in fermented garlic compared to raw garlic is closely related to the browning processes. As the content of Maillard reaction products increases, the synthesis of organic acids increases as a result of the oxidation of aldehyde groups in allodes, which causes a decrease in pH [35; 44; 66; 67; 68]. Additionally, [PERSON] et al. [65] reported that the content of acetic acid increases significantly due to the degradation of hexose during the fermentation processes of garlic. Low pH and high temperature of heat treatment are the most important factors determining the microbiological safety of garlic, because pH below 4.2 allows for a significant reduction in the growth of microorganisms that cause food poisoning. Temperature above 60 \({}^{\circ}\)C and pH below 4.2 allow to inhibit the proliferation of anaerobic bacteria [36]. In addition, at the high temperature of the heat treatment process, low pH ensures greater effectiveness in getting rid of spores of bacteria or fungi responsible for food spoilage [69]. The available literature lacks comparative data on the pH of fermented garlic from conventional and organic cultivation. The results of our own research (Table 1) show that organic garlic, both fresh and fermented, was characterized by a significantly lower pH in relation to garlic from conventional cultivation (by 0.20 in fresh garlic and 0.14 in black garlic, respectively), which could suggest a better technological suitability of organic garlic for fermentation processes and better \"preservation\" effects of black garlic.