Abstract
Riesling wines produced in 1986 and 1988 from vines fertilized with 0, 56, 112, or 224 kg N/ha/year were analyzed in 1991 for free and bound monoterpenes, higher alcohols, and esters. Solid phase extraction using Amberlite® XAD-2 resin was employed in the isolation of volatile compounds identified by gas-liquid chromatography/mass spectrometry. Relative recoveries of all compounds ranged from 79% to 112% with coefficients of variation generally less than 7%. Vineyard N fertilization affected the concentration of some free or bound monoterpenes in the aged wines, depending on the monoterpene and vintage. Concentrations of amyl alcohols and 2-phenylethanol decreased with increasing N fertilization while isobutanol and cis-3-hexen-1-ol showed no differences. Concentrations of 1-butanol, trans-3-hexen-1-ol, benzyl alcohol, and the majority of esters increased (p < 0.05) with increased N fertilization. Sensory analysis using triangle difference tests indicated that wines made from grapes fertilized with 0 or 224 kg N/ha significantly differed (p < 0.01).
- Received July 1992.
- Copyright 1993 by the American Society for Enology and Viticulture