Janja Kristl, Marjan Veber,* and Metka Slekovec
Faculty of Agriculture, University of Maribor, Vrbanska 30, SI-2000
Maribor, Slovenia
*Faculty of Chemistry and Chemical Technology, Aškerčeva 5, SI-1000
Ljubljana, Slovenia
Abstract
In samples taken during different stages of winemaking process (from
grapes, crushed grapes, pressed pomace, must deposit, deposit of lees,
must before and after clarification and wine) the Cu, Mn and Zn contents
were determined by flame atomic absorption spectrometry (FAAS) and the
Cd, Pb and Cr contents were determined by electrothermal atomic absorption
spectrometry (ETAAS). Grapes, crushed grapes, pressed pomace, must deposit
and deposit of lees were microwave digested with nitric acid, hydrofluoric
acid and hydrogen peroxide solution, while for must and wine no special
treatments were necessary. The highest contents of Cu, Mn, Zn, Pb, Cd and
Cr were determined in the pressed pomace, lees, and in white grape varieties
also in must deposit. Mean values obtained of dry weight (pressed pomace,
lees, must deposit) were 63 mg/kg, 300 mg/kg, 184 mg/kg for Cu, 11 mg/kg,
15 mg/kg, 134 mg/kg for Mn, 14 mg/kg, 35 mg/kg, 17 mg/kg for Zn, 0.3 mg/kg,
0.5 mg/kg, 0.6 mg/kg for Pb, 0.5 mg/kg, 1.0 mg/kg, 1.8 mg/kg for Cr, 15.4
?g/kg, 24.4 ?g/kg, 13.0 ?g/kg for Cd. The Cu content was decreasing from
the grapes to the bottled wine, whereas the Mn, Zn, Cd, Cr and Pb contents
in the bottled wine were higher than in musts in all investigated white
and red grape varieties. In ten wine samples the following contents were
determined: Cu; mean 0.12 mg/L (range: 0.06-0.30 mg/L), Mn; mean 1.04 mg/L
(range: 0.60-1.78 mg/L), Zn; mean 0.50 mg/L (range: 0.13-1.03 mg/L), Cd;
mean 0.34 mg/L (range: 0.08-1.04 mg/L), Cr; mean 17.0mg/L (range: 5.2-25.1
mg/L) and Pb; mean 25.3 mg/L (range: 16.4-37.8 mg/L).