Sborník abstraktů 2010 - Fakulta chemická - Vysoké učení technické ...

Markers for organic, conventional
wines and grape wine musts
differentiation
Blanka Tobolková
Supervisor: Martin Polovka, Ph.D
Brno University of Technology, Faculty of Chemistry,
Institute of Food Science and Biotechnology,
Purkyňova 118, 612 00 Brno, Czech Republic;
xctobolkova@fch.vutbr.cz
In the recent years, the consumer’s demand on quality and safety products and
their provision have led to considerable development of organic farming, including
wine production. Consumers have expected that organic wine should be healthier,
pure and naturally produced compared to conventional ones. However, there have
not been recognized any validated methods applicable for authentication of organic
wines and their unambiguous differentiation from wines obtained by conventional
methods. Therefore, there is a need to find objective markers (information, characteristics)
allowing reliable characterization of both types of wines and their classification.
In this contribution, methods of UV-VIS-NIR and EPR spectroscopy were applied
for the evaluation of antioxidant activities and some other characteristics of
Slovak organic and conventional wines and musts prepared from several wellknown
organically and conventionally grown grape varieties. Grapes were pro-
duced in the neighbouringvineyards in order to eliminate the influence of soil soil comcom-
position and climatic conditions on the monitored characteristics. For the easier
comparison of the results, 3 representatives of organic and conventional wines and
respective musts of the same variety were compared.
The ability of samples to terminate • DPPH, ABTS •+ and TEMPOL free radicals,
as well as • OH radicals produced by the thermal decomposition of some radical initiator
were tested by EPR. UV-VIS was involved to monitor the content of polyphenols
in the samples, formation of oxidation products in the presence of thiobarbituric
acid, together with their • DPPH and ABTS •+ quenching and ferric ions reducing
abilities. Their CIE Lab color characteristics were monitored, as well.
All samples showed significant radical-scavenging and antioxidant properties,
the higher for both types of red wines and musts obtained from organic red grape
varieties. Results obtained also indicate that the concentration of polyphenols in
red wines is higher compared to red musts. On the other hand, concentrations of
polyphenols in white wines and musts from white grape varieties are comparable.
Without respect on the way of production, red wines showed approximately two
times higher capability to reduce ferric ions compared to red musts. All musts’ samples
were characterized by the comparable TBARS values (formation of oxidative
products). On the contrary, the higher TBARS values were observed for red wines
compared to white ones. Additional experiments are in progress to obtain as many
characteristics of wines as even possible. Subsequently, their differentiation models
will be constructed by means multivariate statistical methods.