Changes in Biologically Active Compounds During the Ripening Period in Selected Hungarian-Bred Sour Cherry Varieties (Prunus cerasus L.)

The sour cherry (<i>Prunus cerasus</i> L.) is an important fruit species in Eastern Europe due to its multiple uses. The aim of this study was to evaluate the ripening-stage-dependent compositional changes in some Hungarian-bred sour cherry varieties ("amarelle" type 'Korai pipacs', "morello" types 'Érdi bőtermő' and 'Újfehértói fürtös'), with a special view on biologically active compounds (anthocyanins, polyphenols, vitamin C, melatonin), organic acids, sugars, and antioxidant characteristics. The measured soluble solid content varied within a narrower range than reported in the literature, whereas the total acid content and soluble solid content were consistent with previous data. As the analyses were based on samples from a single year (2022), potential year-to-year variability should be considered when interpreting the results. The "morello" type varieties reached a higher amount of different sugar compounds than the "amarelle" type variety. Among the examined organic acid compounds, malic acid was detected in the highest quantity (176.75 to 669.44 mg 100 mL^-1). The vitamin C data (5.74 to 13.46 mg 100 mL^-1) had similarity to the literature data. The "amarelle" type 'Korai pipacs' reached the highest antioxidant content (131.11 mM AS L^-1) in the third picking time. Among the naturally occurring pigments the "morello" type, straining sour cherries reached a higher amount (113.71 µg mL^-1 in 'Érdi bőtermő' and 59.4 µg mL^-1 in 'Újfehértói fürtös' of cyanidin glucosides), than the observed "amarelle" type (23.42 µg mL^-1 in 'Korai pipacs' of cyanidin glucosides). Melatonin was detected in all examined varieties (1.56 to 13.25 ng mL^-1).