CHEMICAL AND ANTIOXIDANT PROPERTIES OF FULLY MATURED RASPBERRY FRUITS (RUBUS IDAEUS L.) PICKED IN DIFFERENT MOMENTS OF HARVESTING SEASON

Abstract

Fruits of the most abundant raspberry cultivars in Serbia (‘Willamette’ and ‘Meeker’) were collected in Šabac growing area, Serbia. The harvest of fully matured raspberry samples from each cultivar is conducted at nearly 2-weeks intervals throughout the harvest season, and further analyzed for main phenolics and antioxidant capacity. Using high-performance liquid chromatography, in all samples quite high content of ellagic acid (from 27.5 to 29.2 mg/100 g fw for ‘Willamette’; from 21.0 to 25.1 mg/100 g fw for ‘Meeker’) and cyanidin (from 38.7 to 43.2 mg/100 g fw for ‘Willamette’; from 21.3 to 30.4 mg/100 g fw for ‘Meeker’) were determined. Significant amounts of quercetin (up to 1.1 mg/100 g fw), apigenin (up to 0.4 mg/100 g fw), gallic acid (up to 6.1 mg/100 g fw), and pelargonidin (up to 5.1 mg/100 g fw) were also detected in all samples. In general, contents of quercetin, apigenin, ellagic acid and cyanidin were higher in fruits of ‘Willamette’ than that of fruits of ‘Meeker’. On the other hand, gallic acid and pelargonidin are more abundant in fruits of ‘Meeker’. In fruits of ‘Willamette’ and ‘Meeker’, the concentrations of main phenolics, and consequently the total anthocyanin, total flavonoid and total phenolic contents, significantly change in fully matured raspberry fruits during harvest season. Determination of antioxidant capacity of all raspberry samples revealed a significant influence of picking moments during harvest season. Furthermore, no significant correspondence between antioxidant capacity and total anthocyanin content was evidenced. On the other hand, an increase in antioxidant capacity corresponds to the increase in the total flavonoid and total phenolic content.