Nitrate Determination in California Musts and Wines

The chemical nitrate method was modified slightly by substituting N-l-naphthylethylene diamine for α-naphthylamine, the color reagent. Reproducibility and recovery were acceptable. White table wines were found to have 2.1 to 53.7 mg/L of NO 3 - with an average value of 16.4 mg/L of NO 3 - . Red wine had 0.9 to 41.4 mg/L of NO 3 - with an average value of 8.5 mg/L of NO 3 - . These values are slightly higher than those reported for European wines. Field nitrogen fertilization of the vines has little effect on the residual nitrate in the grape. Fermentation does not alter the NO 3 - content significantly.