Antioxidant capacity and stilbene contents of wines produced in the Snake River Valley of Idaho

Forty-two wines produced from grapes grown in Idaho were examined in this study. The samples examined were from four mono-varietal wines (12 Cabernet Sauvignon, 9 Merlot, 7 Riesling, 14 Chardonnay). Wine samples represented twelve wineries that obtain their fruit from vineyards located within Idaho's Snake River Valley. Titratable acidity, pH, specific gravity, colour measurements (lightness, chroma, and hue), % haze, total antbocyanins, total phenolics, total tannins, antioxidant capacity, and individual stilbene measurements were performed. The antioxidant capacities (ORAC values) of Idaho wines ranged from 3.1 (Merlot wine) to 87.0 (Cabernet Sauvignon wine) mu mol of Trolox/ml (mean = 38.5 mu mol of Trolox/ml). Mean ORAC values of Merlot wines (mean = 27.6 mu mol of Trolox/ml) were lower than the other three styles (mean for Cabernet Sauvignon wines = 41.0 mu mol of Trolox/ml, mean for Chardonnay wines = 42.8 mu mol of Trolox/ml, and mean for Riesling wines = 39.4 mu mol of Trolox/ml). Free stilbene levels (four different stilbenes) were examined by direct-HPLC/DAD/ESI-MS/MS method. Piceid and resveratrol (both trans- and cis-) were found in the samples. Stilbene levels ranged from 0.97 (Riesling wine) to 12.88 (Cabernet Sauvignon wine) mg (expressed as trans-resveratrol)l/l. This is the first paper to report the current chemical composition of Idaho wines. Published by Elsevier Ltd.