Varietal differences, grape

Duncan, B. (1992). Varietal differences in white grape protein Implications for bentonite fining. Aus. New Zealand Wine Ind.. 7,189-193. 

Cantos, E., Espin, J., and Tomas-Barberan, F., Varietal differences among the polyphenol profiles of seven table grape cultivars studied by LC-DAD-MS-MS. J. Agric. Food Chem. 50, 5691, 2002. 

Little needs to be said of these. They are predominantly of the sherry and port types, and the nature of these types is determined more by fabricating procedure than by the grapes used—though varietal differences are still important in the finer grades. 

Varietal differences between white (top) and red (bottom) grape juices. 

Masa, A., Vilanova, M., Pomar, F. (2007). Varietal differences among the flavonoid profile of white grape cultivars studied by high performance liquid chromatography. /. Chromatogr. A 1164, 291-297. 

These changes have incorporated into the regulations a dual appellation of origin concept with different requirements for each. There also has been an increase of the percentage of a grape variety needed to qualify a wine for a varietal appellation. 

Hernandez-Orte, R, Cersosimo, M., Loscos, N., Cacho, J., Garcia-Moruno, E., Ferreira, V. (2008) The development of varietal aroma from non-floral grapes by yeasts of different genera. Food Chemistry, 107, 1064-1077. 

Definition of different pathogenesis-related (PR) proteins in the ranges 21239-21272 Da and 25330-25631 Da proved potentially useful for varietal differentiation of grapes. The PR protein ESI-MS patterns of juice of the three different white grape varieties are reported in Figure 7.10, differences among varieties are evident (Flayasaka et al., 2003). 

Although compounds from the grapes themselves are responsible for the varietal character of wines, the compounds formed during alcohol fermentation via yeast metabolism may have a positive or negative influence on wine sensory properties (Ferreira et al., 1995). Table 2 shows concentrations of volatile compounds formed paincipjally during the alcoholic fermentation of Rojal red wines over four vintages expressed as mg/1 as mean of two replicates. The major fermentation compounds such alcohols, ethyl esters, acetates and fatty adds were detected at similar total levels in both wines, some minor differences were observed. 

The resulting wines have more intense color and a better tannic structure. They have different aromas, but do not lose their varietal character. This winemaking technique is obviously better suited to some grape varieties than others. 

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