Authors
Title
Abstract
This study presents the content of basic phenolic compounds in the fruit of 11 cultivars of strawberries (Senga Sengana, Thuriga, Polka, Camarosa, Dukat, Elsanta, Onebor, Heros, Kent, Kama and Honeoye), cultivated on experimental plots established in 2004 in Jaroty, near Olsztyn. The analysis included fresh fruit harvested in June 2005. Phenolic compounds were isolated by macerating the fruit four times with 80% methanol. Methanol extracts were analysed to determine the content of general phenolic compounds, anthocyanins, and condensed tannins. Additionally, their DPPH• radical scavenging activity was determined. On the basis of the results obtained, it was established that the Polka and Elsanta cultivars of strawberry had the highest total content of phenolic compounds (over 8,000 mg/100 g of dry mass; per gallic acid), while Kent and Kama varieties showed the lowest value (below 5,300 mg/100 g of dry mass). Anthocyanin content ranged from 29.5 mg/100 g d. m. in fruit of Kent variety, to 79.3 mg/100 g d. m. for Honeoye variety. DPPH• radical scavenging activity varied depending on the cultivar and ranged from 44.8% for strawberries of Honeoye variety to 62.9% for Senga Sengana variety of fruit. For most varieties, there was a positive correlation between the content of general polyphenols and DPPH• radical scavenging activity. Condensed tannins content in the analysed fruit ranged from 977.2 mg/100 g d.m. in the Kent variety of strawberries to 2356.4 mg/100 g d. m. in fruit of the Honeoye variety. There was an inverse proportion between the content of anthocyanins and condensed tannins and the antioxidant activity of the examined varieties of strawberries (r = -0.91).
Keywords
strawberries, general polyphenols, anthocyanins, condensed tannins, antioxidant activity