## 3 Results and Discussion
[45] recorded 1.3-3.5 times increase, and [PERSON] et al. [40] 2-5 times increase in the content of flavonoids in black garlic, depending on the time and conditions of fermentation. However, due to the significant differentiation of the conditions of the applied heat treatment, the comparison of the share of particular groups of flavonoids or specific compounds is difficult and unreliable. Flavonoids are a very diverse group of phenolic compounds, differing not only in their chemical structure (a different number and distribution of hydroxyl groups), but also in thermal stability [74]. For example, in our research, a relatively high content of kaempfer was found in both fresh (5.56 mg/100 g d.m. on average) and fermented garlic (8.89 mg/100 g d.m. on average), while [PERSON] et al. [45] did not detect it at all. These authors also did not show the presence of quercetin in fresh garlic, but only in black one, and in this study it was found on average 11.0 \(\pm\) 0.12 mg/100 g d.m. in fresh and almost 3 times more (30.22 \(\pm\) 4.58 mg/100 g d.m.) in black fermented garlic. As can be seen from the data in Table 2, among the tested flavonoids, flavanols had the greatest share both in fresh and fermented garlic. GREcol was characterized by a significantly higher content of quercetin and kaempfer, and a significantly lower content of myricetin as compared with BG. No such unambiguous regularity was found with regard to the selected catechins identified in the study. Considering potential health benefits, black garlic's most salient property is its high antioxidant potential. As can be seen in Table 2, the tested garlic samples were characterized by a strong ability to inactivate the synthetic ABTS\({}^{+\bullet}\) cation radicals, and thus by a high antioxidant activity. Statistically significant (\(p<\) 0.05) differences were found between all the types of tasted garlic samples. The average antioxidant activity of fresh garlic (all fresh garlic samples, i.e., conventional (GR) and fresh organic (GREcol) garlic) was 318.54 \(\pm\) 46.91 \(\mu\)mol TEAC/g d.m. The applied heat treatment processes increased the antioxidant activity of black garlic to an average of 601.60 \(\pm\) 55.88 \(\mu\)mol TEAC/g d.m. The significantly highest antioxidant potential among all the tested samples was in organic black garlic (BGEcol) and reached the value of 654.93 \(\pm\) 4.54 \(\mu\)mol TEAC/g d.m. Raw materials from organic cultivation are characterized by a higher content of phenolic bioactive ingredients, influencing their higher antioxidant potential, which was confirmed in our own research. Higher concentration of polyphenols compounds in organic black garlic bulbs can be explain by C/N theory [79]. Plants in organic agriculture with limiting organic nitrogen fertilization in first time of their metabolism start to produce compounds with carbon (C.). Polyphenols belong to this group secondary metabolites without nitrogen in their structure [80]. In conventional agriculture when mineral nitrogen fertilization is widely used, plants in first moment start to produce compounds with nitrogen (amino acids, peptides, proteins as well N-containing secondary metabolites, such alkaloids). On the other hands in organic farming using of synthetic plant detector are completely forbidden. Plants have to use they own protection systems such higher concentration of phenolic compounds. Higher concentration of polyphenols are an effect of biotic stresses as pest and diseases [81]. The results of the antioxidant activity obtained in this study are similar to the literature data [40; 82; 83] and confirm the increase in the antioxidant properties of garlic under the influence of the fermentation processes used (twice in this study), while the available literature did not show any data on the influence of the fermentation process on the antioxidant activity of conventional and organic black garlic. [PERSON] et al.