Characterization of the polyphenolic pattern in Prunus domestica cultivars with different fruit skin colour by analysing their fruit juices

Polyphenols like anthocyanins, flavan-3-ols and other flavonoids have proven to be good for human health. Therefore, there is an interest in polyphenols rich fruits like plums. But the European plum cultivars show a large variability in the characteristics of the fruit like form, size, skin colour, sugar content, taste, among others. For that reason it can be expected that the polyphenolic pattern is different between them. This study aims to identify the differences in the polyphenolic pattern of 19 European plum (Prunus domestica L.) cultivars with different fruit skin colours. For that purpose, fruits were harvested during 3 consecutive years. The juice was extracted with methanol using solid phase extraction. The extracts were measured with inverse phase HPLC to identify anthocyanins, flavan-3-ols, flavonols, flavones and hydroxycinnamic acids. After analysing the extracts, two groups were identified in relation to the total flavonoid content. One group of cultivars has a higher amount of total flavonoids than the other. This difference is principally influenced by the amount of hydroxycinnamic acids in the fruit juice, mainly neochlorogenic acid. Flavan-3-ol content is higher in those cultivars with higher flavonoid content. These differences were independent from the skin colour, therefore from the presence of anthocyanin. Flavonol and flavone content are relatively constant in all cultivars. This suggests that the final amount of polyphenols is early regulated in the biosynthetic pathway.