Acid urease derived from Lactobacillus fermentum was applied to reduce ethyl carbamate (EC) formation in California sherry production. Commercial sherry and sherry base were treated with urease under different conditions. Amounts of urea were determined and EC amounts were monitored by gas chromatography. Urea removal by acid urease reduced EC formation during the baking process and effectively maintained EC concentrations below the target level (90 µg/L). However, complete prevention of EC was not achieved because of precursors other than urea.

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Trace amounts of urea (less than 50 @L) in wine were accurately determined using a modified high performance liquid chromatography (HPLC-fluorometric) technique. Appropriate selection of eluent, HPLC columns, and chiral derivatives for the o-phthalaldehyde solution provided a 20-fold enhancement of sensitivity over established methods. A linear relationship was observed at concentrations from 0.5-500 &g/L of aqueous urea solution. The threshold level for detectability of urea in wine was 5 pg/L. The method is simple enough to be applicable to most beverages.

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