The Dynamic of Polyphenols Concentrations in Organic and Conventional Sour Cherry Fruits: Results of a 4-Year Field Study.

Sour cherry fruits are a perfect source of polyphenols, including flavonols, phenolic acids and anthocyanins. According to the literature, organic fruits contain more bioactive compounds, especially polyphenols, compared to conventional fruits. Given that only one two-year experiment on the status of polyphenols in sour cherry fruits in an organic farm was previously conducted and found in the existing scientific literature, the aim of this study was to analyse and compare the concentration of bioactive compounds in organic and conventional sour cherries and to determine the effects of cultivation year and the proper cultivar. Four sour cherry cultivars ("Oblacińska", "Kelleris 16", "Pandy 103" and "Dobroceni Bötermo") harvested in organic and conventional experimental orchards were assessed in this study. The dry matter and polyphenol contents in the fruits were determined. We observed a significantly higher concentration of dry matter in organic samples only in 2015 and 2017. In the case of total polyphenols, including phenolic acid (2015 and 2017-2018), and total flavonoids, including quercetin-3-O-rutinoside, the higher concentration was found in 2016 and 2018. Two individual anthocyanins were identified in sour cherry fruits. Cyanidin-3-O-rutinoside is the predominant form in the pool of total anthocyanins.