Sensory properties and aroma compounds of sweet Fiano wine
Introduction
In some grape growing areas in Europe, such as Germany, France, Hungary and Italy, the production of overripe grapes for special (sweet) wines has a long tradition. Riesling and Semillon grapes are the primary cultivars used in the production of these sweet wines from botrytized or non botrytized grapes. Other varieties, such as Furmint, Picolit, Gewurztraminer, Chenin blanc and Pinot blanc, are used depending on tradition and adaptation to local conditions. In Italy the main varieties used for this wine style are Malvasia and Moscato but also local varieties (Corvina, Rondinella and Molinara) are used as in the case of the famous Amarone wine.
A loss of firmness and a very soft texture, due to the senescence or aging of fruit tissues, are the most evident characteristics of overripe fruit. These physical features increase susceptibility to mechanical damage and infection by pathogens. When the grape is infected by Botrytis cinerea a number of important transformations occur, as well as the loss of water and the release of aroma compounds present in the skin (such as terpenes or C13-norisoprenoids and monoterpenes precursors) into the must (Garcia et al., 2003, Marais, 1992, Park et al., 1991, Razungles et al., 1996).
Generally, the descriptive terms generated for sweet wines are floral, thyme flower, tropical fruit, passion fruit, mango, citrus, orange peel, apricot, dried apricot, peach, marmalade, honey and caramel (Croser, 1989). For Zinfandel the main influence of grape overripeness on wines appears to be intensified ethanol aromas, bitterness, viscosity, and black pepper and berry flavours (Noble & Shannon, 1987).
The volatile compounds identified in sweet wine belong to different chemical classes (Maarse, Visscher, Willemsens, & Boelens, 1992). In particular, a recent study on Tokaj Aszù wine shows that hydroxy-, oxo-, and dicarboxylic acid esters, responsible for coconut, chocolate, peach and fruity odour notes, were present in much higher levels than base wines (Miklósy et al., 2000, Miklósy and Kerényi, 2004).
Recently, interest in sweet wines has increased enormously and various other grape varieties, traditionally destined for dry white wine production, have been employed for these wines.
The aim of this study was to determine the influence of overripeness, drying and Botrytis cinerea on the volatile composition and quality of white wine. The experiment was conducted on the “Fiano” cultivar, the most representative white wine variety in the Campania region of Italy. The sweet and base Fiano wines were analyzed by sensory descriptive analysis and by means of gas-chromatography, gas-chromatography/mass spectrometry and gas-chromatography/olfactrometry.
Section snippets
The experimental wines
Fiano grapes were hand-harvested at full maturation (22 °Brix) in vineyards located in the town of Taurasi (AV), a DOCG area in the Campania region. For Fiano base wine, 2000 kg of grapes were crushed (0.9 atm) and SO2 (50 mg/l) and pectic enzyme (1 g/hl) were added. Must was immediately cooled to 12 °C and was submitted to static decantation (80–100 NTU). Inoculations were carried out at 30 g/hl, after yeast (R7 Lalvin, Lallemand Inc., Castel d’Azzano – Italy) rehydration in warm water for 30 min, as
Sensory descriptive analysis
In Fig. 1, a biplot of the correspondence analysis (CA) is reported. The sensorial attributes of experimental base Fiano wine (B) is very similar to that obtained with a typical Fiano wine reported in a previous study (Moio et al., 2002). They were characterized mainly by fruity notes (banana, apple, pear and pineapple), flower notes (lime, rose and acacia) and vegetable notes (mint, grass and wild fennel). On the contrary, in the sweet Fiano wine (A) these descriptors were less important,
Acknowledgement
We thank Caroline Turner for assistance in preparation of the manuscript.
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