Chemical and Aromatic Characteristics of Brazilian Tropical Wines

Traditional winegrowing areas are located in temperate climate zones and allow to produce grapes only once per year. Tropical wines have been elaborated in India, Thailand, Venezuela and Brazil and present another kind of viticulture, as compared with countries located in temperate climate zones. Northeast of Brazil started wine production twenty six years ago. This region vines can produce two or three crops per year, depending of the cycle of different cultivars. Harvests can be scaled throughout the year, mainly between May and December, corresponding to the dry season. Red, white, rosé and sparkling wines are being elaborated in the region. The objective of this work was to determine the physico-chemical and aromatic characteristics of some tropical wines elaborated in Northeast of Brazil, with grapes harvested in November 2008. Wines were elaborated using traditional method with control of the alcoholic and malolactic fermentation temperatures, at 25 and 18oC for red wines, respectively, and at 18oC for alcoholic fermentation of the white wines. After stabilization and bottling and wines were analyzed to determine physico-chemical characteristics, like alcohol degree, pH, total and volatile acidities, dry extract, sulfur dioxide, total anthocyanin and total phenol index. Aromatic profile was determined by gas chromatography, while 19 esters and 6 superior alcohols were identified. Wines presented different chemical and aromatic characteristics according to different grape cultivars. INTRODUCTION Traditional wines located in temperate climate zones are elaborated in Europe, North and South Americas, South Africa and Oceania, being possible to have one harvest per year, because low temperatures in winter (Reynier, 2003). In Brazil, about 85% of total wines produced are from grapes of Vitis labrusca cultivars, corresponding to 300 million liters per year, and only 15% are from grapes of Vitis vinifera L. cultivars, with about 40 million liters per year. The new Brazilian vitiviniculture zone where tropical wines have been produced is located between 8 and 9 latitude of South Hemisphere and it’s referred to as the Lowermiddle São Francisco river Valley, in Northeast of Brazil. The activity has been developed since the 1980’s, presenting a semi-arid climate with an intra-annual variability (Tonietto and Teixeira, 2004). Wines are elaborated only using grapes of Vitis vinifera L. cultivars, producing about 7 million wine liters in average per year from two harvests. The main climate characteristics of the region present an annual average temperature of 26.4oC (21.0oC for minimum and 31.7oC for maximum temperatures), it is a [email protected] Proc. II IS on Tropical Wines Eds.: G.E. Pereira and J. Tonietto Acta Hort. 910, ISHS 2011 136 located at 350 m above of sea level, in a flat landscape (Teixeira and Azevedo, 1996; Teixeira, 2001). The rainy season occurs from December to March, with about 567 mm of normal rainfall. The heliotermical availability (about 3000 hours of luminosity.year) allows a continuous vegetative development, by using drip irrigation with water from the São Francisco river, and grape cropping is done throughout the year. Wineries normally scaled harvests between eight months, corresponding to the dry season (May to December). The soils are primarily classified as Latosols, with variations in depth and in physical and chemical characteristics. Some works were carried out to evaluate different irrigation levels on vine development (Bassoi et al., 2007), physiological behaviour among irrigation strategies (Dantas et al., 2007), rootstock used and harvest date effects on grape and wine composition (Pereira et al., 2007, 2008a,b; Silva Neto et al., 2009; Araújo et al., 2010). Some volatile compounds in wines are higher alcohols, like 1-propanol, 2-methyl1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol and the 2-methylethanol (Boulton et al., 1996). The fruity aroma in wines normally are reported to the volatile esters (Ebeler, 2001). Red fruit notes are formed by the 2,3-butanodione, methyl vanilate and β-ionone. The acetate of isoamyle and acetate of 2-phenylethyl are reported to citric and peach aroma. Grape notes are originated from the ethylic esters of the 3-methylbutiric, 2-methyl butyric and 2-methylpropanoic acids, and β-ionone, 3-hydroxi-2-butanone (Aznar et al., 2003). Brazilian tropical wines have been elaborated by using grapes of Syrah, Tempranillo, Cabernet Sauvignon, Ruby Cabernet and Petit Verdot, for reds, and Chenin blanc, Moscato Canelli and Sauvignon blanc for whites. For sparkling wines the cultivars are Muscat Italia (sweet), Chenin blanc and Sauvignon blanc (for white sparkling) and Syrah and Grenache (rosé sparkling wines). The aim of this work was to determine some chemical and aromatic characteristics about white and red tropical wines, elaborated in November of 2008. MATERIAL AND METHODS Grapes of the cultivars Syrah, Tempranillo, Petit Verdot, Chenin Blanc, Sauvignon Blanc, Viognier and Verdejo were harvested in November 2008 at optimal maturity. Wines were elaborated by traditional methods (Peynaud, 1997). Red wines were elaborated at 25oC during alcoholic fermentation and at 18oC for malolactic fermentation. White wines were elaborated at 18oC during the alcoholic fermentation. After stabilization and bottling, wines were analyzed to determine alcohol degree, pH, total and volative acidity, total and free SO2, total anthocyanins, polyphenols (Harbertson and Spayd, 2006; OIV, 1990; AOAC, 1990), and aroma compounds. Determination of the 25 compounds, while higher alcohols and esters, were carried out by simultaneously gas chromatography with flame ionization detector (GC-FID) (Bertrand, 1981). Principal component analysis was applied to discriminate between wines and to explain the variability (Pereira, 2005; Kemsley, 1998). RESULTS AND DISCUSSION Forty-two chromatograms were obtained of wines elaborated from six grape cultivars, twenty-one of each compound group, alcohols and esters. An example of a chromatogram obtained of a red wine is showed (Fig. 1). Wines were discriminated according to the chemical composition (data not shown) and aromatic profile. PCA was applied on the aromatic compound results, and wine samples were segmented in different groups according to the aroma profile. Higher alcohols allowed to discriminated between red and white wines. PC1 x PC2 plots explained 74.7% of total variability, that separated clearly red from white wines (Fig. 2). In the positive side of PC1 white wines are located and in the negative side there are the red wines. In the positive side of the PC1 and PC2, are located wines elaborated with grapes from Viognier and Verdejo. The compounds responsible to characterize these wines was identified as 3-methyl-1-butanol. In the positive side of PC2 and in the