Total antioxidant activity of selected grape cultivars (Vitis vinifera L.) studied by electron paramagnetic resonance spectroscopy

Author:

Krunoslav Mirosavljević 1*, Branka Bilić 2  and Teuta Benković-Lačić 1

Received 28 June 2015, accepted 27 September 2015.

Abstract

The total antioxidant activity of three white grape cultivars (Vitis vinifera L.) (Afus Ali, White Chasselas and Chardonnay) and four red grape cultivars (Red Chasselas, Muscat Hamburg, Cardinal and Blue Frankish) conventionally farmed was investigated using electron paramagnetic resonance spectroscopy (EPR), which has the unique ability to directly monitor free radicals and antioxidants in natural environments and systems. Grapes examined in this work originated from the eastern part of continental Croatia (the Slavonia region) and were picked in early September 2010. The spin label used in all of the experiments was a nitroxide-based TEMPO radical (2,2,6,6-tetramethylpiperidine-1-oxyl) with a well-defined EPR spectrum consisting of three equidistant peaks. The obtained results indicated differences in total antioxidant activity among the examined grape cultivars. Muscat Hamburg had the greatest antioxidant activity, very narrowly followed by Afus Ali. The White Chasselas, Cardinal and Red Chasselas cultivars showed moderate antioxidant activity, though still stronger that of the Chardonnay and Blue Frankish cultivars, which were at the end of the list. The experimental results suggested that the table grape cultivars generally had greater antioxidant activity than the wine grape cultivars did. All experimental data obtained from EPR spectra were fitted to a non-linear exponential first-order decay curve using the Levenberg-Marquardt method, in two steps. The high values of R2 parameters obtained for all of the cultivars confirmed the proposition of exponential first-order decay as a mathematical model describing the dynamic properties of spin labels which diminished in the presence of fresh grape juice.

Journal: Food, Agriculture and Environment (JFAE)
Online ISSN: 1459-0263

Year: 2015, Vol. 13, Issue 3&4, pages 7-10.

Publisher: WFL.


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