The Changes of Polyphenols, Flavonoids, Anthocyanins and Chlorophyll Content in Plum Peels during Growth Phases: from Fructification to Ripening

Samples from ‘Stanley’, ‘Vânăt de Italia’ and ‘Tuleu Gras’ plum cultivars were collected from two different positions of the tree crown (i.e., inside, and periphery of the crown) at six different harvesting times, starting with the phase when plum fruits were the size of a bean until they reached full maturity at 21 days intervals. The main phytochemicals of plum skin during fruit development were analyzed. Total polyphenols from plum skin showed variations throughout the fruit growth (200.6 to 1244.5 mg GAE 100g-1), a relatively ascending trend being noticed. For ‘Stanley’ DPPH-Scavenging Activity, statistically insignificant differences (p > 0.05), with values between 47.4% and 51.5%, were found, similar trends being observed for ‘Vânăt de Italia’ and ‘Tuleu Gras’. The total flavonoid content in the analyzed plum fruits statistically significantly decreased (p < 0.05) from fructification to ripening for ‘Stanley’ and ‘Tuleu Gras’. On the other hand, variations were registered for ‘Vânăt de Italia’ cultivar which had the highest flavonoid content on the sixth harvesting phase. Anthocyanin content accumulated in ‘Vânăt de Italia’ plum peel showed increasing values during fruit development, regardless of the harvesting phase, variety or position, while a slightly decreasing trend was found for ‘Stanley’ and ‘Tuleu Gras’ varieties. The largest quantity of total chlorophyll (287.4 µg g-1) was found in the fructification phase, followed by a continuous decrease until ripening, whatever the variety or crown position.