# Selected Antioxidants in Organic vs. Conventionally Grown Apple Fruits
## 3 Results and Discussion  
Apple is currently the most widely cultivated and one of the most commonly consumed temperate fruits. It is considered as one of the most important fruit sources of antioxidants such as phenolics and vitamin C in the Western diet [3]. After flavanols (catechin and oligomeric procyanidins), known as the major class of apple fruit polyphenols, hydroxycinnamic acids, and flavonoids, follow as the second and third most abundant classes, constituting together 3-41% of all apple phenolics [20]. The profiles of these biologically active compounds in fruits and vegetables are known to be impacted by genetic (species, cultivar), environmental, and agricultural factors, including those related to the cultivation practices [24]. The apple fruit samples analyzed within this study contained, on average, \(15.41\pm 2.92\) mg/100 g f.w. of phenolic acids (mainly chlorogenic acid), \(4.46\pm 1.96\) mg/100 g f.w. of the selected identified flavonoids and \(12.85\pm 5.21\) mg/100 g f.w. of vitamin C (mainly L-ascorbic acid) (Tables 1-3). The concentrations and profiles of the analyzed phenolic compounds as well as vitamin C in the tested apple samples were generally within the ranges reported by other authors [7; 25; 26]. The horticultural production system had a significant impact on the concentrations of the majority of the analyzed antioxidants in apples. Organic apples, compared to the conventionally grown ones, were characterized by significantly higher concentrations of phenolic acids (av. \(>\)31%) and the analyzed flavonoids (av. \(>\)66%), with the direction of differences being consistent across apple cultivars and harvest seasons (Table 4, Figures 3 and 4). The identified interactions (SYS \(\times\) CV and SYS \(\times\) YR) in case of both groups of phenolic compounds (phenolic acids and flavonoids) reflected mainly the variation in the magnitude of organic vs. conventional apples composition differences between cultivars and harvest seasons (Figures 3 and 4, Table 4), i.e., the greatest production system effect on the phenolic acids (sum) concentration in apple fruits harvested in both seasons was observed in the Idared cultivar. The magnitude of the differences in flavonoid (sum) concentrations was greater in 2017 compared to the 2018 harvest season. This supports the findings of the recently published meta-analysis on the composition of organic vs. non-organic plant-based foods, which reported that organically cultivated fruits and vegetables are, on average, up to 60% richer in phenolics when compared to the conventionally cultivated ones. However, significant heterogeneity between results was reported for different species, locations, and other conditions [19]. [PERSON] et al. (2005) [27], in their study on \(11\) apple cultivars from organic and integrated production in Austria and Slovenia, found higher contents of phenolics in the pulp (but not peels) of organically cultivated apples compared to the fruit coming from integrated production. The authors explained the higher concentrations of phenolic compounds in the pulp of organically grown fruits as a result of increased plant responses to stress in the organic system. [PERSON] et al. (2010) [28] measured the effect of organic and integrated cultivation on the content of phenolics in fruits and leaves of four apple cultivars over a two-year period. The authors underlined that phenolics in fruit may be influenced by many factors such as the fruit type, cultivation, and environmental conditions, growing season, storage environment, and time, and, lastly, by processing and preservation methods. However, in their study, higher levels (10-20%) of total phenolics as well as of each of the analyzed groups of phenolic compounds (hydroxycinnamic acids, flavanols, dihydrochalcones, quercetin) were found in organic vs. integrated apple fruit and leaves. At the same time, [PERSON] et al.