Antioxidant Capacities and Phenolic Levels of Different Varieties of Serbian White Wines

The biologically active compounds in wine, especially phenolics, are responsible for reduced risk of developing chronic diseases (cardiovascular disrease, cancer, diabetes, etc.), due to their antioxidant activities. We determined the contents of total phenolics (TP) and total flavonoids (TF) in selected Serbian white wines by colorimetric methods. Total antioxidant activity (TAA) of the white wines was analyzed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay. Međaš beli had the highest content of TP, TF and TAA. The radical scavenging capacity (RSC) and total antioxidant activity (TAA) of white wines were 15.30% and 1.055 mM Trolox equivalent, respectively. Total phenolic (TP) and total flavonoid (TF) contents in white wines ranged from 238.3 to 420.6 mg gallic acid equivalent per L of wines and 42.64 to 81.32 mg catechin equivalent per L of wines, respectively. A high and significant correlation between antioxidant activity and total phenolic content was determined in wines (R2 = 0.968, p < 0.01). For the individual polyphenols determination we used a high performance liquid chromatography (HPLC)-diode array detection (DAD) technique. The majority of white wine polyphenols was represent by four hydroxycinnamic acids (HCAs)

Polyphenol Content and Antioxidant Activity of Sour Cherries From Serbia

The aim of this study was to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant\ud capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the investigated sour cherries,\ud „Oblačinska“ cultivar contained the highest amounts of all groups of phenolics, followed by „Cigančica“ > „Marela“. A significant difference were observed in the phenolic content among different cultivars and growing seasons (p  0.05), and the phenolic compounds were significantly higher in the growing season 2009. The examined cultivars possess a high antioxidant capacity, and all phenolics of highy correlation with TAC. The following compounds were identified and quantified using HPLC-DAD: 4 anthocyanins, the most abundant of which was cyanidin-3-glucoside in “Marela” and “Oblačinska”, and cyanidin-3-glucosylrutinoside in „Cigančica“, and 4 hydroxycinnamic acids, the most abundant of which was neochlorogenic acid in all sour cherry cultivars. The growing and ripening process on the tree of sour cherry cv. „Oblačinska“ was evaluated also. The results showed significant increases in total phenols during the ripening, the total anthocyanins and total antioxidant capacity and 4 quantified anthocyanins, however the neochlorogenic acid decreased during the ripening. The study indicated that the growing and climate conditions in southeast Serbia are convenient for introducing sour cherry cultivars.\u

Conductometric and pH metric investigations of the oxalic acid and NaAsO2 reaction

The reaction between NaAsO2 and oxalic acid was studied by pH-metric and conductometric measurements, applying the methods of continual variation and pH-metric and conductometric titration. It was found that oxalic acid forms a complex anion of the type [AsOC2O4]-. The relative stability constant of the complex at ionic strengths, I, of 0.10 (log Kr = 4.70), 0.20 (log Kr = 4.51), 0.50 (log Kr = 4.24) and 0 (log K0r = 5.05) and thermodynamic para¬meters were calculated using the data obtained by pH-metric measurements at 25.0±0.1 °C (DH = 10.5 kJ mol-1, DG = –29.0 kJ mol-1, DS = 133 J mol-1 K-1)

Phytochemical profiles and antioxidant activities of Serbian table and wine grapes

International audienceThree table grapes and 4 wine grapes collected from a southern Serbian vineyard were evaluated and compared for their antioxidant properties and phenolic profile. Among the varieties tested, 'Cabernet Sauvignon' contained the highest total phenolic content with 173.6 mg/100 g of fresh weight. Also, the total flavonoid and antocyanin content of 'Cabernet Sauvignon' was significantly higher from the other. 'Cabernet Sauvignon' and 'Merlot' had the strongest DPPH center dot radicals scavenging activity (1,318.6 and 1,282.0 mu mol Trolox equivalent/100 g, respectively). 'Cabernet Sauvignon', 'Merlot', 'Prokupac', 'Vranac', 'Muscat Hamburg', and 'Ribier' grape varieties were found to be rich in malvidin-3-O-glucoside, while 'Cardinal' grape variety was found to be rich in peonidin-3-O-glucoside. The following compounds were also identified and quantified using HPLC-DAD: 2 flavan-3-ols and 4 hydroxycinnamic acids in all grape samples. The results suggested that phytochemicals in the selected table and wine grapes have potent antioxidant activities in correlation with phenolic content