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
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).