Effect of timing of Diammonium Phosphate addition to fermenting grape must on the production of Ethyl Carbamate in wine英文电子书.pdf

Research Note Effect of Timing of Diammonium Phosphate Addition to Fermenting Grape Must on the Production of Ethyl Carbamate in Wine 1 1 Calvin Adams and Hennie J.J. van Vuuren * Abstract: 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. Key words: nitrogen supplementation, ethyl carbamate, urea, Saccharomyces cerevisiae Ethyl carbamate (EC), also known as urethane, is a is degraded into ornithine and urea by arginase encoded known carcinogen that occurs naturally in many ferment- by the CAR1 gene (Sumrada and Cooper 1984). Since urea ed foods and beverages (Zimmerli and Schlatter 1991). becomes toxic to yeast cells at higher concentrations, yeast In 1985, a study conducted by the Ontario Liquor Board cells secrete urea into the wine where it spontaneously (Canada) determined that a number of alcoholic beverages, r