The grape varieties

The extensive number of cultivars in the Douro and their adaptation to its different climatic conditions are proof of the region s ability to offer optimal conditions for vine growth and fruit maturation. There are more than 150 grape varieties, a substantial portion of which originated in the region (Cardoso and Silva, 2007). However, the grape varieties that 

Normally, port wine is considered to be a red wine. Nonetheless, white grape varieties represent 34% of the vine coverage (Guenael, 2005). Some of the enologically important parameters of the red cultivars are presented in Table 5.2. They are the most studied cultivars. 

TABLE 5.1 Grape varieties recommended and the percentage according to which each may be planted to the production of red and white port wines 

40% Donzelinho Malvasia Periquita Rufete Tinta Barca Donzelinho Branco Samarrinho 

TABLE 5.2 Enological parameters of recommended red grape varieties (adapted from Abade and Guerra, 2008) 

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Classification of wines according to the grape variety succeeds better, in general, because there are many more typical bouquet components (several hundreds) than mineral and trace elements being typical for the origin of wine. The organic compounds can be analyzed easily and reliably by Headspace Solid-Phase Microextraction Capillary Gas Chromatography and afterwards used for classification (De la Calle et al. [1998]). An example... 

The amounts of analytes are compiled in Table 2.74. The results indicated that the concentration of polyphenols in red wines depends on both the grape variety and on the exogenous factors. The validation parameters of the method were good, the recoveries were in each case over 98 per cent, the coefficients of variation were between 1.3 per cent and 4.3 per cent, and the limit of detection ranged from 10/rg/l to 0.1mg/l. It was stated that the method is suitable for the determination of silbene compounds and quercetin in red wines [194],... 

Figure 5-5. A. MALDI mass spectrum of the anthocyanin pigments in the grape variety Marechal Foch. This figure is from the article Matrix-assisted laser desorption ionization mass spectrometry analysis of grape anthocyanins , Am. J. Enol. Vitic. 50 199-203 by Sugui, J. A., Wood, K. V., Yang, Z., Bonham, C. C. and Nicholson, R. L. 1999. Reprinted by permission of the American Society for Enology and Viticulture. B. MALDI mass spectrum of grape anthocyanins acquired on a MALDI mass spectrometer with delayed extraction capabilities. Peak identities are discussed in the text.

The amount of anthocyanins in purple grapes varies with the grape varieties (75MI1,98JAFC368, 73WW181) ... 

As will be explained in more detail below, all Italian Vin Santo production traditionally follows the same basic scheme, although there are major differences in the grape varieties used and in the degree of grape drying these lead to the different types and styles of Vin Santo. 

Wines without a designation of origin current wines (table wines), and wines with an indication of the grape variety and the vintage (varietal wines). 

Similarly, as for the production of other passito wines from partially dried grapes, such as Recioto, Albana passito, and Picolit (which we refer to as "non-aromatic passito wines"), generally the grape varieties and clones used should be those with a thicker skin and more open clustered small berries, as these are best for drying under mild conditions, with less... 

These compounds have a strong influence on the quality and character of the wine and are therefore important not only for the wine characterization but also reflects the history of the wine producing process, including the grape variety, the yeast strain, the containers used for fermentation and storage, and the enological practices. Their nature and... 

Tirage involves filling the bottle with the base wine (wine from the first fermentation, produced by the usual techniques of white wine production), monovarietal or made from a mixture of wines (in both cases the grape varieties used are appropriate for this type of production) and the addition of a solution called tirage liquor. 

Flor yeasts efficiently transform young wine obtained from sensory neutral grapes into genuine, internationally appreciated wine with a high aroma potential. In fact, wine aroma is dictated by the particular flor yeasts rather than by the grape variety used. 

The type of oak wood used is also important, since the volatiles released by different types of oak usually differ hence so do the resulting wines. Tasters tend to prefer a balance between the oak aromas ordinarily produced by the oak lactones and the grape variety s own fruity aromas (Perez-Coello et al. 2000b). 

Wine is a complex mixture consisting of indigenous components and those obtained by chemical and biochemical transformations by wine microorganisms and/or during wine aging. Wine composition varies widely and is influenced by the grape (variety, quality) and by the winemaking conditions. 

Additionally, hydroxycinnamates are important constituents of acylated antho-cyanins. In red wine, the 6-6>-coumaroylglucosides and caffeoylglucosides are common constituents (Mazza and Miniati 1993). In the authenticity control of red wine the relation of acetylated and coumaroylated anthocyanins can be used for the assessment of the grape variety (Holbach et al. 2001 Otteneder et al. 2002). 

Factors Affecting their Concentration in Wine. Studies of the occurrence of isobutylmethoxypyrazine (1) have shown that it has a consistent and systematic relationship to the grape variety and the vine growing conditions. 

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