Chemosensory And Viticultural Studies Of Hybrid And Non-Vinifera Grape Species And Resulting Wines
Native American grape species and hybrid varieties have several desirable properties compare to Vitis vinifera, but the effect of canopy treatment on them and the aromas inherent to most Vitis species are not well characterized. Two canopy treatments were applied to two hybrid varities growing at commercial vineyards in the Finger Lakes region of New York State, including Marechal Foch and Coort noir. The experiments were conducted for two growing seasons. For Marechal Foch, yields and clusters were reduced while berry weight was increased by shoot thinning. Shoot thinning reduced crop load and increased soluble solids in 2008. Shoot thinning increased berry anthocyanins, but no corresponding increase was observed in wine anthocyanins. Delaying harvest resulted in increases of soluble solids, berry and wine anthocyanins. Both treatments resulted in decreased sixcarbon alcohols in finished wines. The total concentration of tannin in Foch fruit was comparable to that of some vinifera. However, the extractability of tannins during winemaking was very low compared to most vinifera. Sensory panelists reported that later harvest 2008 wines were more "fruity" than their early harvest counterparts for both treatments and that shoot thinning did not affect fruitiness. For Corot noir, yield was reduced by cluster thinning (CL) but not shoot thinning (ST) in 2008. CL increased Brix in both of years. The treatments had variable impacts on wine anthocyanin, berry skin tannin, berry seed tannin, and wine tannin depending on year. Wine tannin and tannin extractability were both very low in comparison to vinifera. Panelists reported ST+CL wines were more "fruity" than the control in both years. The key odorants in wine produced from the American grape species, V. riparia and V. cinerea were determined. Non-vinifera wines had higher concentrations of odorants with vegetative and earthy aromas: eugenol, cis-3-hexenol, 1, 8- cineole, isobutylmethoxypyrazine (IBMP) and isopropylmethoxypyrazine (IPMP). Concentrations of IBMP and IPMP were well above sensory threshold in both nonvinifera wines and some grape accessions. We expect that this knowledge will facilitate the selection of interspecific hybrids by grape breeders, or could be used to identify targets for viticultural or enological studies on interspecific hybrids.
Sacks, Gavin Lavi
Vanden Heuvel, Justine E.; Acree, Terry Edward
Food Science & Technology
Ph.D. of Food Science & Technology
Doctor of Philosophy
dissertation or thesis