Food Control 18 (2007) 398–403 www.elsevier.com/locate/foodcont Aroma proWle of wines from Albillo and Muscat grape varieties at diVerent stages of ripening E. Sánchez Palomo a, M.C. Díaz-Maroto a,b,¤, M.A. González Viñas a, A. Soriano-Pérez a, M.S. Pérez-Coello a a Área de Tecnología de los Alimentos, Facultad de Ciencias Químicas, Universidad de Castilla-La Mancha, Campus Universitario 10, 13071 Ciudad Real, Spain b IRICA (Instituto Regional de Investigación CientíWca Aplicada), Universidad de Castilla-La Mancha, Campus Universitario 10, 13071 Ciudad Real, Spain Received 11 July 2005; received in revised form 23 November 2005; accepted 26 November 2005 Abstract Volatile composition of musts and wines from Muscat “a petit grains” and Albillo grape cultivars harvested at diVerent states of ripening, was evaluated. Among the volatile compounds analysed by GC/FID/MS, wines obtained from less ripe grapes displayed higher ester and fatty acid concentrations, but less terpene compounds and benzene derivatives, than wines from grapes with a high degree of maturity. Maturity also greatly inXuenced wine aroma. In all cases, wines from grapes with higher sugar content were more fruity and less vegetal and Xoral. © 2005 Elsevier Ltd. All rights reserved. Keywords: Aroma; Wine; Grape; Ripening; OAV 1. Introduction Wine aroma is formed by hundreds of volatile compounds of diVerent chemical natures and origins, found at a wide range of concentrations. Compounds arising from grape metabolism (terpenes, norisoprenoids, benzene compounds and C6 alcohols) vary as a function not only of the variety but also of certain cultural and climate-related factors (Bureau, Razungles, & Baumes, 2000; Jackson & Lombard, 1993; Zoecklein, Wolf, Marcy, & Jasinski, 1998). These compounds can appear either in their free form, playing a key role in the quality and the peculiar aroma of wines, especially in aromatic grape varieties such as Muscat, or bound to sugar mole- * Corresponding author. Address: Área de Tecnología de los Alimentos, Facultad de Ciencias Químicas, Universidad de Castilla-La Mancha, Campus Universitario 10, 13071 Ciudad Real, Spain. Tel.: +34 926 295300; fax: +34 926 295318. E-mail address: [email protected] (M.C. Díaz-Maroto). 0956-7135/$ - see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2005.11.006 cules, being odourless (Günata, Bayonove, Baumes, & Cordonnier, 1985; Williams, Sefton, & Wilson, 1989). In neutral grape varieties, other compounds formed during yeast fermentation or released from conjugated forms by chemical or enzyme hydrolysis may play a more important role in the overall aroma of the wine (Cabaroglu, Canbas, Lepoutre, & Günata, 2002; Sefton, Francis, & Williams, 1993). In this respect, the processing techniques or the type of yeast strain used may prompt some modiWcation of the Wnal aroma, although the contribution of the grape variety predominates (Antonelli, Castellari, Zambonelli, & Carnacini, 1999; García Romero, Pérez Coello, Cabezudo, Sánchez-Muñoz, & Martín-Alvarez, 1999). One of the factors most inXuencing the aroma characteristic of a given variety is the stage of ripening of the grape. Both free and glycosylated forms of varietal compounds are accumulated in the grape during ripening (Bayonove, 1993). Terpene content may decrease once optimal sugar levels are attained, although this may be inXuenced by temperature and water availability during ripening (RibereauGayon, Glories, Maujean, & Dubourdieu, 2000). E.S. Palomo et al. / Food Control 18 (2007) 398–403 The time of harvest is traditionally governed by must sugar content, or determined by reference to certain indices linking sugar content with acidity (Ribereau-Gayon et al., 2000). However, these indices are not always matched by the aromatic maturity of the grape (Girard, Fukumoto, Mazza, Delaquis, & Ewert, 2002; Schneider, Razungles, Charrier, & Baumes, 2002). Advanced grape maturity and greater exposure to the sun favour the accumulation of varietal compound in the berry (Schneider et al., 2002). Lower canopy densities may produce an increase in glycosidically-bound compounds in the berry (Jackson & Lombard, 1993; Zoecklein et al., 1998). Late-harvested Garnacha grapes yielded wines with less -ionone and cis-3-hexen-1-ol and more -damascenone and geraniol than those early-harvested (Sabon, Revel, Kotseridis, & Bertrand, 2002). However, not all volatile compounds aVect the overall wine aroma. The olfactory perception threshold for each compound varies considerably; the olfactory impact of a compound will thus depend on whether it is present at concentrations above this threshold. Over recent years, sniYng techniques, calculation of olfactory thresholds for a wide range of compounds, and the use of OAVs (odour activity values) have enabled the identiWcation of numerous odorants in wines from several grape varieties (Guth, 1997; Lopez, Ortín, Pérez-Trujillo, Cacho, & Ferreira, 2003; Schneider, Razungles, Augier, & Baumes, 2001). Muscat “a petit grains” is an aromatic variety containing a fairly typical amount of terpene compounds, although less than Muscat of Alexandria (Bureau et al., 2000; Castro Vázquez, Pérez Coello, & Cabezudo, 2002). Since Albillo is a neutral variety and has a low terpene content, it has been traditionally used as table grape. However, recent studies have demonstrated that wines made from Albillo grapes contain interesting Xavour notes (Jurado, Pinilla, Ballesteros, Pérez-Coello, & Cabezudo, 2001). The purpose of this study was to determine the eVect of the grape ripening degree on the aroma of wines made under the same fermentation conditions, using one aromatic variety (Muscat “a petit grains”) and one neutral variety (Albillo), both grown in a sunny and warm climate. 2. Materials and methods 2.1. Samples Grapes from Vitis vinifera varieties Muscat “a petit grains” and Albillo cultivated in the La Mancha region (Spain) were harvested at diVerent stage of ripening in two vintages. Laboratory fermentations using 3 L vessels were carried out in duplicate, and inoculated with Saccharomyces cerevisiae race cerevisiae yeasts (CECT no. 10835). 2.2. Isolation of volatile compounds Varietal compounds were extracted from musts and wines using the method developed by Günata et al. (1985). 399 Two hundred millilitres of must or wine were fractionated on preconditioned styrene-divinylbenzene cartridges (Bond Elut, Varians, 1 g of phase), using 4-nonanol as internal standard, with subsequent elution with 50 mL of pentane– dichloromethane (2:1). Extracts were concentrated on a Vigreux column to a Wnal volume of 200 L. Fermentation compounds were isolated by continuous liquid–liquid extraction with pentane–dichloromethane (60:40). 4-Nonanol was used as internal standard. The extracts obtained were concentrated on a Vigreux column and injected into a GC column. 2.3. Gas chromatography conditions A Hewlett–Packard model 4890 gas chromatograph equipped with a Xame ionisation detector (280 °C) was used with a BP-21 capillary column (50 m £ 0.32 mm i.d.; 0.32 m Wlm thickness). Injector temperature was 250 °C and oven temperature was set at 70 °C (5 min), then raised at 1 °C/min to 95 °C(10 min), and then raised at 2 °C/min to 190 °C (40 min). Carrier gas was He (0.7 mL/min). Injection volume was 1 L in splitless mode (0.6 min). IdentiWcation was made by comparison of GC retention times with those of authentic standards from Sigma–Aldrich, and by CG–MS (Hewlett–Packard G 1800 B GCD System). For quantiWcation purposes, calibration curves were used when standards were available, otherwise semiquantitative analysis was performed assuming a response factor equal to one. 3. Results and discussion Table 1 shows results for °Brix, pH, and total acidity of musts obtained from Albillo and Muscat “a petit grains” varieties harvested in both 2001 and 2002, together with some of the most widely used maturity indices (Coombe, Dundon, & Short, 1980; Ellis, Van Rooyen, & Du Plessis, 1985). With reference to the results for °Brix, it should be pointed out that the 2001 harvest was delayed, and grapes of both varieties were riper than grapes from the 2002 vintage. As was to be expected, total acidity was lower for the 2001 harvested grapes, although acidity results for Muscat “a petit grains” were still higher than expected. Attending the maturity indices, although the most widely used is the °Brix/volatile acidity ratio, a value of 3.1 being considered optimal for grapepicking, indices involving pH are considered better predictors of harvest quality. The optimal value for °Brix £ pH2 lies between 200 and 270, while for °Brix £ pH, the optimum is between 85 and 95 (Boulton, Singleton, Bisson, & Kunkee, 1996). There was no correlation between these indices, in our results for Muscat “a petit grains” grapes, the 2001 vintage had a acceptable maturity index according to the °Brix/volatile acidity ratio, but not using the others two indices. In Albillo grapes the °Brix £ pH index was adequate for the 2001 vintage but not the other two indices. 400 E.S. Palomo et al. / Food Control 18 (2007) 398–403 Table 1 °Brix, pH, total acidity and maturity indices of musts obtained from Muscat “a petit grains” and Albillo varieties from the vintages 2001 and 2002 °Brix pH Total acidity (g (H2T)/L) °Brix/total acidity (g (H2T)/L) °Brix £ pH2 °Brix £ pH Muscat “a petit grains” 2001 Muscat “a petit grains” 2002 Albillo 2001 Albillo 2002 26.5 3.3 8.3 3.2 288.6 87.5 21.6 3.2 8.6 2.5 221.2 69.1 25.1 3.5 4.2 6.0 307.5 87.9 21.6 3.3 5.7 3.8 235.2 71.3 Table 2 Volatile compound concentration (g/L) of musts obtained from Muscat “a petit grains” and Albillo varieties from the vintages 2001 and 2002 Compounds Muscat “a petit grains” 2001 Muscat “a petit grains” 2002 Albillo 2001 Albillo 2002 Mean Mean RDS (%) Mean RDS (%) Mean 55.1 218.5 6.3 59.9 391.1 7.4 5.9 11.9 1.5 1.5 40.0 113.9 18.0 28.3 274.2 6.3 5.1 3.6 11.5 4.9 19.3 140.9 15.9 17.0 284.3 RDS (%) 2-Hexenal 1-Hexanol (E)-3-Hexen-1-ol (Z)-3-Hexen-1-ol (E)-2-Hexen-1-ol 37.3 63.9 34.1 3.5 102.7 6.8 8.3 4.9 5.7 5.6 Total C6 compounds 241.5 Benzaldehyde Benzyl alcohol 2-Phenylethanol 116.4 118.0 Total benzenic compounds 234.4 Geraniol Linalool Hotrienol -Terpineol Citronellol Nerol Geranic acid 165.6 197.5 82.6 36.9 8.7 3.4 4.1 11.9 103.0 4.6 Total monoterpenes 585.6 730.9 9.8 10.3 6.8 142.8 102.0 514.2 11.9 9.7 11.4 251.6 110.3 103.0 13.7 9.5 6.4 104.1 100.2 545.2 Tr 60.9 51.1 112.0 8.2 11.2 4.3 9.7 9.8 9.7 1.0 RDS (%) 4.1 2.4 1.8 0.8 1.8 477.4 7.8 6.1 7.9 133.1 54.9 5.1 11.0 11.4 188.0 13.4 2.5 13.4 2.5 Tr: traces. In conclusion the utility of these indices is limited and they do not oVer information about the quality of wines obtained. The aroma is one of the main factors related to the quality of white wines and compounds responsible for wine aroma should be taken in account in the evaluation of the optimal stage of grape ripening. Results for quantiWcation of the varietal compounds in Albillo and Muscat musts for both harvests are shown in Table 2. Muscat musts from the 2002 vintage, when harvested grapes were less ripe, displayed higher C6 alcohol concentrations than those harvested in 2001. By contrast, concentrations of terpene compounds (monoterpenes and oxygenated terpenes) were lower in 2002. Similar Wndings are reported by other authors for a number of grape varieties (Bureau et al., 2000; Sabon et al., 2002; Schneider et al., 2002). In the Albillo variety, however, little terpene compounds were detected, and C6 alcohol levels were very similar for both harvests, although slightly higher for 2001. The opposite was true of benzene compounds. The results for a given harvest may be strongly inXuenced by weather factors (temperature, rainfall) during ripening (Marais, Van Wik, & Rapp, 1992), and results for volatile composition varied between harvests for the same grape variety, independently of sugar content (Dieguez, Lois, Gómez, & de la Peña, 2003). During the fermentation process varietal compounds can suVer some changes, for instance 1-hexanol was greater in wines than in musts and (E)-2-hexen-1-ol and 2-hexenal were not detected in wines, probably due to transformations by yeast metabolism. On the other hand in Muscat a petit grains wines some monoterpenes, such as linalool, hotrienol and citronellol, were higher than in the must, but others decreased: geraniol and nerol. Table 3 shows the varietal compound concentrations of wines from Muscat “a petit grains” and Albillo for the two vintages. Regarding the total amounts, Muscat “a petit grains” wines from 2002 contained higher C6 alcohol than wines from 2001 vintage. However Albillo wines displayed similar C6 alcohol content in both vintages. More terpene compounds were found in Muscat “a petit grains” wines; concentration were lower in 2002, as they were for musts. Benzene compounds were lower in 2002 for Muscat wine. With regard to fermentation compounds (Table 4), production of fatty acid esters and acetates was lower in 2002, E.S. Palomo et al. / Food Control 18 (2007) 398–403 401 Table 3 Varietal compounds concentration (g/L) of wines obtained from Muscat “a petit grains” and Albillo varieties from the vintages 2001 and 2002 Compounds Muscat “a petit grains” 2001 Muscat “a petit grains” 2002 Mean RDS (%) Mean 1-Hexanol (E)-3-hexen-1-ol (Z)-3-hexen-1-ol 267.8 46.5 18.5 3.2 2.6 11.9 547.6 38.6 36.1 Total C6 compounds 332.8 Geraniol Linalool Hotrienol -Terpineol Citronellol Nerol Geranic acid 20.6 273.5 138.2 34.0 27.8 Tr 171.5 Total monoterpenes 665.6 Benzaldehyde Benzyl alcohol Tr 594.6 Total benzenic compounds 594.6 Albillo 2001 RDS (%) 7.2 5.3 0.9 622.3 7.0 2.9 5.7 3.5 8.7 Mean RDS (%) Mean RDS (%) 481.6 87.6 44.9 6.0 7.4 2.5 607.8 52.2 10.8 2.2 4.4 13.5 614.1 61.6 147.7 93.9 39.2 100.7 Tr 84.4 5.9 Albillo 2002 670.8 3.1 7.0 4.2 9.5 1.4 1.5 3.2 1.5 Tr 226.1 6.9 15.6 527.5 6.6 327.4 12.9 3.2 3.6 0.1 334.0 Tr 219.6 – 9.4 219.6 226.1 Tr: traces. Table 4 Volatile compounds from fermentation (mg/L) of wines obtained from Muscat “a petit grains” and Albillo varieties from the vintages 2001 and 2002 Compounds Acetaldehyde Methanol 1-Propanol Isobutanol 3-Methyl-1-butanol 2-Methyl-1-butanol 3-(Methylthio)-1-propanol 2-Phenylethanol Total alcohols Muscat “a petit grains” 2001 Muscat “a petit grains” 2002 Albillo 2001 Mean Mean Mean 45.2 61.2 14.2 14.9 87.0 17.9 0.5 20.1 67.9 5.3 0.05 0.2 0.9 1.2 1.1 1.0 0.3 10.1 Total esters 88.0 Total acids 0.1 4.5 1.6 0.6 0.7 1.4 3.0 7.7 261.0 Ethyl acetate Isoamyl acetate Hexyl acetate Phenylethyl acetate Ethyl lactate Ethyl hexanoate Ethyl octanoate Ethyl decanoate + Isovaleric acid Diethyl succinate Ethyl 4-hydroxybutyrate Isobutyric acid Butyric acid Hexanoic acid Octanoic acid Decanoic acid RDS (%) 0.8 0.9 4.9 6.2 2.7 15.5 44.5 21.5 24.0 28.9 167.2 42.5 0.9 15.8 RDS (%) 8.6 4.3 4.1 4.9 2.0 4.3 3.5 7.2 345.3 1.9 12.6 8.7 9.2 0.3 6.3 2.3 4.3 8.6 10.5 24.9 1.7 0.01 0.01 0.6 0.5 0.3 2.2 0.06 7.6 1.5 0.7 2.0 3.0 0.7 7.9 but fermentation alcohols were slightly higher in this case. Given that fermentation conditions and the yeast strain used were the same, diVerences observed in both varieties may be attributed to the diVerent sugar content and must composition between vintages. RDS (%) Mean RDS (%) 0.5 1.2 1.6 2.9 10.1 2.8 8.0 4.7 19.8 27.0 10.0 17.6 123.7 45.4 1.4 31.0 2.5 10.1 15.9 4.4 2.0 10.0 3.3 1.6 209.6 9.5 0.2 9.9 17.3 2.1 4.6 3.1 22.6 5.4 24.4 37.88 2.0 11.7 9.2 10.4 3.4 14.3 37.7 14.2 15.2 86.2 21.4 0.4 20.2 Albillo 2002 46.0 2.9 0.03 0.1 0.4 1.2 1.0 0.9 0.2 13.1 275.9 1.7 2.3 1.5 2.7 4.9 8.8 2.6 5.6 8.7 8.4 65.83 5.1 17.8 5.2 6.1 0.6 1.2 0.4 4.4 5.5 1.7 13.2 20.9 3.7 0.03 0.2 1.1 0.7 0.8 2.3 0.1 6.8 1.8 0.3 11.9 10.7 4.9 8.8 6.1 3.4 6.2 1.0 36.63 3.0 2.7 3.0 2.4 7.9 1.7 0.6 2.1 3.4 1.0 11.0 8.7 2.0 2.5 6.1 8.8 In order to assess the inXuence of the compounds studied on overall wine aroma, odor activity values (OAV) were calculated by dividing the concentration of each compound by its perception threshold. Of all the compounds analysed, only those displaying OAVs greater 402 E.S. Palomo et al. / Food Control 18 (2007) 398–403 Table 5 Odour activity values (OAVs) of volatile compounds with more inXuence in the aroma of wines obtained from Muscat “a petit grains” and Albillo varieties harvested in 2001 and 2002 Compounds Sensory descriptor Odour threshold (g/L) Muscat “a petit grains” 2001 Muscat “a petit grains” 2002 Albillo 2001 Albillo 2002 Linalool Geraniol Hotrienol 2-Phenylethanol Acetaldehyde 3-methyl-1-butanol 3-(Methylthio)-1-propanol Ethyl acetate Isoamyl acetate Ethyl hexanoate Ethyl octanoate Flowery Citric Hyacinth Roses, sweet Pungent, ripe apple Burnt, alcoholic Cooked vegetables Fruity, solvent Banana Fruity, green apple, banana Fruity, banana, pineapple, peach, sweet Sweet, grass Rancid Cheese Grass acid 15a 30a 110b 10 000a 500a 30 000a 500a 7500a 30a 5a 2a 18.18 0.67 1.25 2.02 90.50 2.90 1.07 9.05 177.37 239.23 547.50 9.85 2.05 0.85 1.58 89.09 5.57 1.80 3.33 58.19 91.02 151.25 2.02 28.68 2.87 1.05 6.14 94.36 236.43 527.33 3.10 39.63 4.12 2.77 2.79 121.93 132.97 392.54 2.01 20.00 1.63 12.4 5.00 41.92 0.65 6.08 1.75 16.57 1.46 11.00 4.75 37.43 0.71 6.81 Ethyl decanoate Isovaleric acid Hexanoic acid Octanoic acid a b c 200c 33.4c 3000a 500c Guth (1997). Etiévant (1991). Ferreira et al. (2000). than 1 were deemed to contribute to wine aroma (Guth, 1997). Table 5 shows the OAVs for the compounds that have values greater than 1, together with sensory descriptors and the perception threshold taken from the literature. Muscat “a petit grains” contained a group of compounds with Xoral or citric odours, i.e. terpenes (linalool, hotrienol, and geraniol). Other terpenes identiWed, including citronellol and -terpineol, were present at concentrations below, although occasionally close to the odour threshold. These compounds give to Muscat wines their characteristic aroma, and there may be some synergic eVect involving all the monoterpenes that gives rise to the deWning “moscatel” aroma (Ribereau-Gayon et al., 2000). In wines made from grapes harvested in 2002, hotrienol concentrations were below its odour threshold, while geraniol concentrations were above it. The terpene displaying the highest OAV value was linalool; similar Wndings have been reported for other aromatic varieties including Albariño and Gewürztraminer (Falqué, Fernandez, & Dubourdieu, 2001; Ong & Acree, 1999). C6 alcohols were present at concentrations below their odour thresholds in all cases. Fermentation alcohols with major sensory impact were 2-phenylethanol, which displayed a characteristic rose aroma and 3-methyl-1-butanol. Medium-chain fatty acid esters and acetates tend to present fruity aromas and may play a major sensory role, especially in neutral grape varieties containing negligible amounts of terpenes (Cabaroglu et al., 2002; Lopez et al., 2003). Ethyl octanoate and hexanoate displayed high OAV values in both wines and for both vintages. Some fatty acids were present at levels over the perception threshold in both grape varieties. These compounds displayed fatty aromas, cheesy or rancid, that were not perceived in the overall wine aroma, perhaps because they were overwhelmed by other more intense aromas. The same was true for the “boiled-vegetable” aroma of 3-methylthiopropanol. The tasting panel scored wines made from Muscat “a petit grains” as having a intense, Xoral, typically “Muscat” aroma, and a moderate fresh and fruity odour. Wines from Albillo grapes had citric and fruity aromas (melon, green apple, peach), with Xoral notes. In all cases, wines from the 2002 harvest scored lower than those of the 2001 harvest in terms of aroma intensity. Acknowledgements The authors thank to the Ministerio de Educación y Ciencia (project AGL2004-07205) and to Mercadona S. A. for the Wnancial support, and to M. Dolores Cabezudo for her scientiWc assistance. Eva Sánchez-Palomo would like to thank the Ministerio de Educación, Cultura y Deporte for the award of a grant. 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