## 3 Results and Discussion
According to the conducted research, the pH of fresh, unprocessed garlic (WG) was 6.37 \(\pm\) 0.04, which is in line with the results of other authors showing a pH in the range of 5.99-6.52 [18; 25; 26]. Long-term heat treatment, resulting in the formation of black garlic, significantly (\(p<\) 0.05) decreased this parameter (on average to 3.80 \(\pm\) 0.27 for the tested black garlic products). Other authors also showed this tendency [18; 19; 20; 31; 32]. [PERSON] et al. (2021) [25] obtained results similar to ours, showing a significant decrease in pH for fresh unprocessed garlic (6.46) to about 3.79-4.44 in black garlic (depending on the time of heat treatment). In addition, [PERSON] et al. (2022) [36] found a significant decrease in pH from about 6.01 for fresh to 4.09 for black garlic during the aging process. The lowering of the pH during the aging process of black garlic depends on the conditions of its course. Lower pH is obtained in a product fermented over a longer period of time [42] or at a higher temperature [41; 42]. According to the literature, the low pH in black garlic is a result of the Maillard reactions occurring during the aging process, leading to an increase in the synthesis of organic acids such as formic, succinic, 3-hydroxypropionic or pyroglutamic acid due to the oxidation of aldehyde groups in aldoses [20; 44], or the degradation of hexose increasing the acetic acid content [45]. In the garlic samples tested in the study, the content of soluble solids (\({}^{\circ}\)Brix) was significantly (\(p<\) 0.05) the lowest in unprocessed, fresh garlic (WG) (35.88 \(\pm\) 1.35%), and the applied process of long-term heat treatment resulted in a significant increase of this parameter for all black garlic products, averaging at a value of 47.78 \(\pm\) 3.15%. The obtained results are consistent with the studies of other authors [18; 28; 31; 42]. Among the tested black garlic \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **WG** & **BG-C** & **BG-P** & **BG-S** \\ \hline Dry matter (\%) & 37.14 \(\pm\) 0.13 \({}^{\rm a}\) & 56.96 \(\pm\) 0.42 \({}^{\rm c}\) & 98.84 \(\pm\) 0.06 \({}^{\rm d}\) & 45.40 \(\pm\) 0.99 \({}^{\rm b}\) \\ Moisture (\%) & 62.86 \(\pm\) 0.13 \({}^{\rm d}\) & 43.03 \(\pm\) 0.42 \({}^{\rm b}\) & 1.16 \(\pm\) 0.06 \({}^{\rm a}\) & 54.60 \(\pm\) 0.99 \({}^{\rm c}\) \\ Water activity (a\({}_{\rm w}\)) & 0.98 \(\pm\) 0.00 \({}^{\rm d}\) & 0.94 \(\pm\) 0.00 \({}^{\rm c}\) & 0.20 \(\pm\) 0.00 \({}^{\rm a}\) & 0.93 \(\pm\) 0.00 \({}^{\rm b}\) \\ pH & 6.37 \(\pm\) 0.04 \({}^{\rm d}\) & 3.94 \(\pm\) 0.05 \({}^{\rm b}\) & 3.45 \(\pm\) 0.04 \({}^{\rm a}\) & 4.02 \(\pm\) 0.01 \({}^{\rm c}\) \\ \({}^{\circ}\)Brix (\%) & 35.88 \(\pm\) 1.35 \({}^{\rm a}\) & 46.95 \(\pm\) 0.10 \({}^{\rm c}\) & 51.74 \(\pm\) 0.48 \({}^{\rm d}\) & 44.66 \(\pm\) 0.32 \({}^{\rm b}\) \\ \hline \hline \end{tabular} Values are means \(\pm\) standard deviation (\(\pi=3\)). Different letters (\({}^{\rm a}\)–d) in the same line are significantly different (\(p<\) 0.05). WG—white garlic; BG–C—black garlic cloves; BG–P—black garlic powder; BG–S—black garlic spread.  
\end{table} 
Table 1: Physicochemical characterization of white garlic and black garlic products. products, the highest value for \({}^{\circ}\)Brix was found in BG-P powder (51.74 \(\pm\) 0.48%). As reported in the literature, the increase in the content of soluble solids depends on the time and temperature of the garlic aging process, as well as on the way the material is fermented (in the form of head/cloves) [28] and finally on the variety of garlic and its condition as a crop (conventional/ecological cultivation) [31; 32; 42]. According to the literature, the increase in soluble solids content in black garlic is mainly attributed to the processes of hydrolytic degradation of polysaccharides to oligosaccharides and monosaccharides [27; 46], accompanied by an approximately 80% increase in the content of reducing sugars determining the characteristic sweet taste of black garlic [47; 46; 48].