engleski

Evaluation of phenolic content, antioxidant capacity and quality of chokeberry juices (Aronia melanocarpa) from Croatian market

In the past few years, consumers have shown a growing interest in food and food products rich in polyphenols. Chokeberries (Aronia melanocarpa) is a distinctive berry with a high content of polyphenols commpounds and has one of the highest in vitro antioxidant activity among fruits. The aim of this study was to determine the physicochemical properties, the content of phenolics and antioxidant properties of chokeberry juices (Aronia melanocarpa) present on the Croatian market. The physicochemical analyses included determination of colour parameters, soluble solids, pH value, total solids and total titratable acidity. The total phenolic content (TPC), nonflavonoid content (TN) and flavonoid content (TF) were determined spectrophotometrically according to the Folin–Ciocalteau procedure ; while total anthocyanin content (TA) was determined using pH- differential method. Antioxidant properties of juices were measured by 2 tests: total antioxidant capacity (TAC) using DPPH free radical assay and ferric reducing antioxidant power (RP) using FRAP assay. CIE L*a*b* system was used to monitor colour parameters. Chokeberry juices had a mean pH value of 3, 79 and ranged from 3, 54 to 3, 92. The mean total titratable acidity was 0, 92 % malic acid and ranged from 0, 28 % to 1, 26 %. Total solids content ranged from 13, 42 to 21, 54 % with mean value of 15, 90 % while the content of soluble solids ranged from 14, 30 °Brix to 22, 10 °Brix (mean value was 16, 61 °Brix). All juices contained high mass fraction of TPC (2055, 22 to 3903, 01 mg/100 g DM) and TF (1439, 91 to 3098, 47 mg/100 g DM) and lower mass fractions of TN (494, 18 to 1070, 24 mg/100 g DM) and TA (97, 86 to 915, 26 mg/100 g DW). Examined juices possess high antioxidant capacity (5, 61 to 29, 69 mmol TE/100 g DM) and reducing power (23, 91 to 55, 08 mmol Fe2+/100 g DM). The study indicated that there are significant differences (p<0, 05) in physicochemical properties, total phenol, flavonoid, nonflavonoid and anthocyanin content as well in the total antioxidant capacity and reducing power between chokeberry jucies available on Croatian market. Positive correlation between a* values (redness) and TA (R = 0, 54) as well between hue tone and TA (R=0, 61) were observed.

antioxidant capacity ; chokeberry ; colour ; phenols ; reducing power

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