Yingxin Miao* and Andrew Waterhouse
*University of California, Davis , One Shields Avenue, Davis, CA, 95616
(yxmiao@ucdavis.edu)

Aging capacity is an essential factor in wine quality. The aging capacity of white Burgundy dropped between the vintages of 1995 to 2000, which impacted the reputation of Burgundy wine. An accurate and rapid aging capacity test is needed to better predict shelf life. We compared four proposed methods: the FRAP assay, a modified DPPH assay, the iron species ratio, and the sulfur dioxide addition method. These methods are designed to assess “antioxidant” capacity or quantity, not the speed of reactivity. The FRAP assay reflects the capacity of the wine to reduce Fe (â…¢) to Fe (â…¡). The DPPH method (EC20) measured the volume of samples needed to reduce 20% of DPPH free radicals in 10 min. The FRAP and DPPH assays approximately reflected the concentrations of ascorbic acid, sulfur dioxide, and phenols. The iron species ratio was measured before and after an air saturation for one day to test for resistance to Fe (â…¡) oxidation by air. Prior to air exposure, Fe (â…¡) was the primary iron species (>92%) and the decrease varied widely after a one-day air saturation. The sulfur addition method determines weakly bound SO2, which is part of bound sulfur, but this form will release free SO2 during oxidation. The FRAP assay, DPPH assay, and weakly bound SO2 correlated strongly, while the iron species ratio method had low correlation with other methods. An accelerated oxidation procedure will be compared using these tests.

Funding Support: University of California, Davis