Content of flavonols and selected phenolic acids in strawberries and Vaccinium species: influence of cultivar,cultivation site and technique

The amounts of flavonols (quercetin, myricetin and kaempferol) and phenolic acids (ellagic, p-coumaric, caffeic and ferulic acids) were analysed in six strawberry cultivars and in the berries of genus Vaccinium (four blueberry cultivars, wild bilberry, wild bog whortleberry). Differences between strawberries from organic vs. conventional cultivation were investigated and the influence of geographical origin on phenolic compounds of strawberries and blueberries was studied. Three different extraction and hydrolysis procedures together with two HPLC methods with diode-array UV/vis detection were used. The varietal differences in the total content of the phenolics analysed were larger among the cultivated blueberries (from 4.4 to 9.2 mg/100 g, fresh weight) than among the strawberry cultivars (from 42.1 to 54.4 mg/100 g). Some regional differences were observed in the phenolic contents in blueberries and strawberries. Compared to conventional cultivation techniques, organic cultivation had no consistent effect on the levels of phenolic compounds in strawberries.