Las levaduras y la baja producción de urea y de carbamato de etilo

Ethyl carbamate is a toxic compound that may be formed spontaneously by the chemical reaction between carbamyl compounds synthezised during the nitrogenous metabolism of microorganisms taking part in the vinification process and ethanol, the major alcohol in wine. In this work we made a survey of the concentration of ethyl carbamate in young, cru and reservee Spanish red wines from different wineries belonging to representative appelation controlee areas, as well as assessed the effect of alcoholic fermentation conducted by pure yeasts strains of Vitis Vinifera cv. Tempranillo ans Cabernet Sauvignon musts on the formation of urea and ethyl carbamate. In addtion, the incidence of different nitrogenous substrates present in must (urea, puric bases, ammonium ions, arginine) on the production of urea and ethyl carbamate during alcoholic fermentation was studied. Spanish red wines showed concentrations of ethyl carbamate below 30 ppb (≤ 25 ppb), and the best correlations were recorded with ethyl lactate and volatile acidity. During the alcoholic fermentation of Tempranillo and Cabernet Sauvignon musts either no ethyl carbamate was formed under the physicochemical conditions tested or low concentrations were recorded (≤ 1.3 ppb). Alcoholic fermentation of musts enriched with nitrogenous substrates produced low ethyl carbamate levels irrespective of either the yeast strain used or the prevailing physicochemical conditions of the fermentation (≤ 1.5 ppb). Generally, regarding urea levels recorded at the end of the alcoholic fermentation it was concluded that small quantitities of ethyl carbamate would be formed under normal storage conditions of the wines.