Paul Mawdsley, Federico Casassa,* Emily Stoffel, Patricia Williams, and Jean C. Dodson Peterson

A control wine (100% Syrah) and five Syrah blends (consisting of additions by weight of 10% pressed solids of Marsanne, Roussanne, Viognier, Picpoul blanc, and Grenache blanc during crushing) were made on an experimental scale. In addition, juice from each white cv. was fermented separately and blended at a 10% rate into finished Syrah wine after malolactic fermentation to compare the effects of cofermentation and postfermentation blending. It was hypothesized that the addition of white grape solids could result in color enhancement and different phenolic profile relative to 100% Syrah, as opposed to postfermentation blending. Wines were followed during the winemaking process to assess the effect of white fruit addition on wine chemistry, color, and phenolic composition and up to 14 months of bottle aging. At pressing, tannin and polymeric pigment content were not significantly affected in any treatment, while catechin and anthocyanin content were. Syrah-Viognier and Syrah-Marsanne had more anthocyanin content than other cofermentation treatments, although still lower than the control. There was a statistically significant reduction in color among cofermented wines relative to 100% Syrah, with Syrah-Grenache blanc showing statistically larger reduction in color (chroma, a*) than other cofermentation treatments. Full spectrum color analysis revealed that all postfermentation blended wines had higher absorbance in the 500 to 540 nm range both after seven and 14 months bottle aging. Conversely, cofermentation generally lowered color relative to the uncofermented Syrah wine at these two time points. Although total anthocyanins, polymeric pigments, and total phenolics changed during bottle aging, no significant interaction was found between wine age and treatment, indicating that the cofermentation treatment had no effect on the evolution of phenolic profile post-fermentation. A detailed anthocyanin characterization by HPLC and a complete descriptive sensory analysis of the wines are also reported.

Funding Support: Baker and Koob Endowment for Undergraduate Research. Panelists from the Trained Wine Sensory Panel at Cal Poly are also thanked for their professionalism and commitment with this study