Selecting the optimal harvest time is a strategic aspect of sour cherry production, as profound changes in fruit chemical composition occur during ripening, influencing both sensory quality and nutraceutical value.
A recent study conducted on three Hungarian sour cherry cultivars, the amarelle-type cultivar 'Korai pipacs' and the morello-type cultivars 'Érdi bőtermő' and 'Újfehértói fürtös', investigated the evolution of the main bioactive compounds across three different ripening stages, highlighting how genetic background and fruit maturity determine markedly different quality profiles.
The researchers monitored changes in sugars, organic acids, vitamin C, polyphenols, anthocyanins, melatonin, and antioxidant capacity, demonstrating that each cultivar follows a distinct metabolic pattern during fruit ripening.
In all cultivars, soluble solids content increased progressively, whereas the sugar-to-acid ratio, a key determinant of flavour perception, proved to be strongly dependent on the genotype.

Sugars and acids
The morello-type cultivars accumulated higher concentrations of glucose, fructose, and other sugars than the amarelle-type cultivar, confirming their suitability for both fresh consumption and industrial processing.
Among the organic acids, malic acid was confirmed as the predominant compound responsible for the characteristic acidity of sour cherries.
At the same time, vitamin C content increased throughout ripening in all cultivars, reaching the highest levels in 'Újfehértói fürtös'.
However, the differences observed among cultivars demonstrate that the final fruit composition results from the interaction between genetic background and the physiological stage of development, making harvest management tailored to specific production objectives essential.
Vitamin C and fruit development
The morello-type cultivars also exhibited higher concentrations of anthocyanins, particularly cyanidin glycosides, the natural pigments responsible for the intense red colour of the flesh and juice.
'Érdi bőtermő' recorded the highest cyanidin levels, while 'Újfehértói fürtös' showed an especially high total polyphenol content.
The progressive accumulation of these metabolites during ripening confirms that harvesting at the later stages maximizes both the nutraceutical value of the fruit and its potential use as a natural source of food colourants for the food industry, an increasingly valuable attribute given the growing demand for natural ingredients to replace synthetic pigments.
In contrast, although the cultivar 'Korai pipacs' contained lower concentrations of sugars and anthocyanins than the morello-type cultivars, it exhibited the highest melatonin content, a compound well known for its antioxidant properties and its role in regulating circadian rhythms.
Anthocyanins and melatonin
Overall, the study confirms that there is no universally superior cultivar, but rather varieties with distinct production potentials.
'Érdi bőtermő' and 'Újfehértói fürtös' stand out for their high antioxidant content, favourable sugar-to-acid balance, and abundance of natural pigments, making them particularly suitable for both the fresh market and industrial processing.
By contrast, 'Korai pipacs' represents a promising resource for the production of functional foods thanks to its high melatonin content and lower sugar concentration.
Overall, monitoring the ripening process is essential for identifying the optimal harvest time and maximizing the qualitative and nutraceutical potential of different sour cherry cultivars.
Source: Ficzek, G., Simon, G., Gergely, M., Mehmeti, S., Krasniqi, V., Mali-Gáspár, E., Komma, L., Vegvari, G. & Bujdosó, G. (2026). Changes in Biologically Active Compounds During the Ripening Period in Selected Hungarian-Bred Sour Cherry Varieties (Prunus cerasus L.). Plants, 15(5), 713. https://doi.org/10.3390/plants15050713
Image source: Stefano Lugli
Andrea Giovannini
PhD in Agricultural, Environmental and Food Science and Technology – General Arboriculture and Tree Crops, University of Bologna, Italy
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