ON THE ORIGIN OF ORGANOLEAD COMPOUNDS IN WINE

The speciation pattern of organic lead has been determined in 22 sampl es of French wines from the Cotes du Rhone and the Rhone Valley region s, seven samples of Californian wines and two samples from Australia a nd Argentine. Methyllead species were ubiquitous in French wines (whit e, rose and red) while generally absent in American wine samples. A po ssibility of biomethylation of mineral lead has been examined by inves tigating the organolead speciation pattern at various stages of the al coholic and malolactic fermentation both in natural grape must and in a synthetic matrix enriched in lead(II). No methylation of lead was ob served while a slow degradation of triethyllead occurred as the fermen tation was progressing. No formation of organolead compounds could be detected in lees and burbes where yeast and lactic bacteria can work u nder anaerobic conditions. This indication of the atmospheric origin o f organolead in wine is further supported by much larger concentration s of organolead found in older vintages (even from the US and Australi a) than in the present ones which is attributed to the decreasing use of leaded gasoline.