engleski

Seasonal variation of phenolic content and antioxidant capacity of chokeberry juices

Variations in physicochemical properties, content of phenolics and antioxidant activity of chokeberry juices (Aronia melanocarpa) were investigated. The physicochemical analyses included soluble solids, total solids, pH value and titratable acidity. The total phenolic content, nonflavonoid content and flavonoid content were determined spectrophotometrically using the Folin-Ciocalteu reagent while total anthocyanin content was determined using pH- differential method. Total antioxidant capacity was determined by DPPH and FRAP assay. Growing seasons differed in the content of soluble solids which ranged from 19, 81 to 27, 40 ° Brix and in total solids from 19, 22 to 26, 79 %. pH value ranged from 3, 77 to 3, 96 and titrable acidity from 0, 854 to 1, 015 % malic acid. Total phenolic content and total flavonoids in the three growing seasons ranged from 8833, 916 to 11092, 816 mg GAE/L and 6993, 625 to 9709, 644 mg GAE/L respectively. Among examined growing seasons the highest content of TA (2767, 977 mg CGE/L) was found in growing season 2012. All chokeberry juices possess high antioxidant activity (12, 856 – 14, 560 mmol TE/L ; 128, 216 - 166, 647 mmol Fe2+/L), and all phenolics were highly correlated with total antioxidant capacity and reducing power. This study indicates that although examined properties vary considerably through the growing seasons (p<0, 05), chokeberry juices can serve as a good source of bioactive phytochemicals in human diet.

chokeberry ; phenols ; antioxidant activity ; growing seasons

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