Dynamics of ripening and phenolic content of grapes from the white varieties Chardonnay, Dimyat and Druzhba, grown under the soil and climatic conditions of the town of Pleven

Tatyana Yoncheva, Anatoli Iliev, Dimitar Dimitrov

Abstract: A study was carried out on the ripening process and the phenolic content of grapes from the varieties Chardonnay, Druzhba and Dimyat, grown in the region of Pleven. It covered two consecutive harvests 2021 – 2022. The change in the meteorological indicators temperature, relative air humidity, the amount of precipitation and their average monthly values throughout the vegetation period was monitored. During the winter months, critically low temperatures for the vine plant growth were not registered in the region. The vegetative development of the vines started in the middle (2021) or the beginning (2022) of April. During the grapes ripening period, the dynamics of sugars and the change of titratable acids were monitored. Faster sugar accumulation and reaching technological maturity were reported for Chardonnay and Druzhba varieties. In Chardonnay, despite the high sugar rates, relatively high titratable acids were preserved. Dimyat ripened the latest, with a gradual increase in sugars and a decrease in acids. The highest sugar accumulation in Chardonnay and Dimyat varieties was found in 2021 while for Druzhba in the grapes from the 2022 harvest. The differences in the weather conditions of the year did not significantly affect the phenolic composition of the grapes. The varietal characteristics, specificities and the potential were more pronounced in the phenolic content of the structural elements of the cluster. The varieties had different content of total, flavonoid and non-flavonoid phenolic compounds, which increased in the order of berries < skins < rachis < seeds. The Druzhba variety had better phenol content, followed by Chardonnay, and the lowest rate was in Dimyat.

Keywords: Chardonnay; climate; Dimyat; Druzhba; grapes; phenolic content; ripening; soil

Date published: 2023-08-24