# Selected Antioxidants in Organic vs. Conventionally Grown Apple Fruits
## 3 Results and Discussion
was characterized with the lowest gallic acid content among the three cultivars when grown in the organic system, but it contained the highest concentrations of this compound when grown conventionally (Table 4). Caffeic acid concentrations in the fruits were higher in 2017 when compared to the 2018 growing season (which was consistent for all cultivars in both production systems). However, some interactions between the factors were also identified. While in the organic system, Champion cv. presented the highest contents of caffeic acid among all cultivars in both years. In the conventional system, such a consistent cultivar effect was not confirmed. In 2017 Gala cv. was richest in caffeic acid, but, in 2018, the same cultivar contained the lowest concentrations of this compound among all tested cultivars. In case of \(p\)-coumaric acid, large differences between harvest seasons were observed in Champion and Idared cv. (with lower contents of \(p\)-coumaric acid in 2018 compared to 2017) while Gala was characterized by similar (high) contents of this compound in both seasons. Moreover, when comparing apples from organic vs. a conventional system, content of p-coumaric acid was consistently higher in those organically grown (except for Gala cv. harvested in 2017) (Table 4). Quercetin-3-O-rutinozide constituted in most cases nearly 90% of the individual flavonoids identified in the tested apple fruits. The described differences in the analyzed flavonoids (sum) content in apples reflected, therefore, in most cases, the differences in the quercetin-3-O-rutinozide content (Table 4). In case of other identified flavonoids (quercetin and kempferol-3-O-glycoside), various trends in the effects of the production systems and cultivars in the two harvest seasons were observed (withsignificant 2-factor and 3-factor interactions). In case of both compounds, higher concentrations were identified in organic vs. conventional apples during the 2017 harvest season with no such trend observed in 2018 (Table 4). Vitamin C content in the fruits was strongly dependent on the year-to-year differences in the fruit growing conditions. Higher concentrations of vitamin C were generally found in apples harvested in 2018 (\(17.23\pm 2.44\) mg/100 g f.w.) compared to 2017 (\(8.47\pm 3.07\) mg/100 g f.w.) (Figure 5). Moreover, strong interactions between harvest season, cultivar, and production system were observed in case of the concentrations of this compound, i.e., Gala apples were characterized by the lowest concentrations of L-ascorbic acid in 2017, but were richest in this compound in the following year (especially in the conventional production system). Moreover, while in 2017 Gala apples were richer in vitamin C when grown in the organic system, in 2018, an opposite production system effect was observed in this cultivar with higher concentrations of vitamin C in the conventionally cultivated fruit. Only in case of Idared cultivar, the consistent production system effect across both harvest seasons was observed with higher concentrations of vitamin C found in the organic fruit when compared to the conventionally grown fruit (Figure 5). L-ascorbic acid was the main vitamin C fraction in the apple fruit, constituting more than 87% of the total vitamin C content. Thus, the described differences in the vitamin C content in apples, in most cases, were reflected in the differences of the L-ascorbic acid content. The highest concentrations of L-ascorbic acid were found in conventional Gala apples harvested in 2018, and the lowest concentrations were found in both organic and conventional Gala apples harvested in 2017. There was an interesting pattern of dehydroascorbic acid concentrations in the apples. In the organic system, the highest concentrations of dehydroascorbic acid were identified in Gala cv., while, in the conventional system, Champion apples were richest in this compound. This trend was consistent in both harvest seasons.