engleski

Antioxidant activity of sweet wine Prošek using Briggs-Rauscher reaction

Briggs-Rauscher reaction is an oscillating reaction and the oscillations are quenched, when free radicals are added. When in a suspension free radicals are exhausted oscillations reappear. The period without oscillations is called an inhibition time (IT) and is monitored potentiometrically. The inhibition time is proportional to the concentration of antioxidants of an added sample. Briggs-Rauscher reaction is a very appropriate and applicable method for determination of antioxidant activity since the pH of the reaction is about 2, what is pH of a human stomach. Therefore, obtained results of the measured antioxidant activity for tested samples of sweet wine Prošek are more realistic and related the efficacy of antioxidants in a human body. Antioxidant activity was determined in the grape samples and during the production of Croatian sweet (dessert) wine Prošek obtained from autochthonous cultivars of Plavac mali and Pošip. Effect of different temperature of storage on antioxidant activity of wine samples was also investigated. Phenol content of selected sweet wine samples was determined by spectrophotometric method with Folin-Ciocalteus reagent using gallic acid as a calibration standard, expressed as galic acid equivalent (GAE). Each sample is determined by three parallel tests. By use of mathematical models, relative antioxidant activities of antioxidants and amounts of total phenols are estimated. In the model, the antioxidant activity is the output value calculated according input value, the total phenols. The model is estimated in the range of 100-3200 galic acid equivalent (GAE mg/l), with standard error of 105 GAE mg/l.

antioxidant activity ; Briggs-Rauscher ; prošek

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