Evaluation of Antioxidant Activity of Products of Grape Processing by Amperometric Method and Bioluminescent Test
Phenolic composition of juice, wine stocks (Merlo, Cabernet) and food concentrates (Enoant, Fenokor) from red grapes from Crimea and Krasnodar region is presented in the work. Flavonoids are presented by anthocyanins, oligomeric procyanidins and polymeric ones are in significant amount, which consist the main part of polyphenols of wine stocks and concentrates from red grapes. Among nonflavonoid polyphenols it was identified hydroxybenzoic and hydroxyl-cinnamic acids; the largest content of which in the total polyphenols were registered in juices, the smallest one-in concentrates. An experimental equation in obedience to results of quantitative physical and chemical analysis of samples and their antioxidant activity by Trolox method was obtained: Y = 0.53627 + 0.1395X + 0.080439X2 - 0.00064708X3, r = 0.9952; Y is antioxidant activity, g/dm3 by Trolox method; X is mass concentration of phenolic substances according to the Folin-Ciocalteu method, g/dm3. The equation is valid for Y from 0.76 to 196.22 g/dm3 by Trolox method; X from 1.0 to 82.67 g/dm3. The biological test of antioxidant action of the studied samples of wine stocks (Merlo, Cabernet) and food concentrates (Enoant, Fenokor) was carried out by luminescent method using bacteria Photobacterium leiognathi Sh1 and enzyme luciferase. Bioluminescent reaction was examined as a model system, and its suppression-as a result of the antioxidant action. Two model antioxidants: gallic acid and quercetine (Corvitin) were used as the standards. Standard antioxidants had identical suppression influence on bacteria, which was registered in 10 minutes of exposition and in 18-hour test. The similar effect was caused by tested wine stocks of red grapes and grape concentrates. The correlation of antioxidant activity values, obtained by the biotest with bioluminescent bacteria (18 h), with results of high performance liquid chromatography (HPLC) and results, obtained by the methods of Folin-Ciocalteu and Trolox, is 0.75-0.81.