Effect of Timing of Diammonium Phosphate Addition to Fermenting Grape Must on the Production of Ethyl Carbamate in Wine

Grape must is often supplemented with diammonium phosphate (DAP) to reduce stuck fermentations. The timed addition of DAP to grape must significantly affects the amount of ethyl carbamate (EC) produced in wine. This effect was found to be yeast strain dependent: Pasteur Red produced less EC when DAP was added at the onset of fermentation, whereas strain 522 produced less EC when DAP was added during the later stages of fermentation. EC production by strain EC1118 was less affected by the timing of DAP addition. The metabolically enhanced yeast strains Pasteur RedEC-, 522EC-, and EC1118EC-, which constitutively express DUR1,2, significantly reduced the amount of EC produced regardless of the timing of DAP addition.