Aroma Components of Galician Albariö.O, Loureira and Godello Wines
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Vitis 33, 165-170 (1994) Aroma components of Galician Albariö.o, Loureira and Godello wines by 1 ) Laboratorio di Analisi e di Ricerca, Istituto Agrario di San Micheie all' Adige, San Micheie all' Adige, Italia 2 ) Estaci6n de Viticultura y Enologia de Galicia, Leiro, Espagne S u m m a r y : Wines of the three most interesting Galician white grape varieties have been deeply analyzed for three aroma categories: the volatile compounds, except for monoterpenols, the monoterpenols and the bound forms. Many compounds showed significant differences between the wine groups, as proved by Tukey's test, e.g. for methanol, trans and cis 3-hexen-1-ols andre levant ratio, benzaldehyde and 4-vinylguaiacol in the first category, and for the most part of compounds of the other two categories. Loureira and most Albariiio wines contain linalool and ho-trienol at a Ievel of sensorial contribution. The relevant average terpene profiles show many similarites, especially for Albariiio and particularly if considering the contents and relevant ratios of furan and pyran linalool oxide isomers, of ho-diendiols I and II and of geraniol. On the other band differences could be stated for some compounds, mostly under the bound forms. Godello wines, with the poorest content of monoterpenols under both forms, are principally characterized by a marked Ievel of bound benzaldehyde, with contemporary presence of a considerable average Ievel of the free form. PCA data treatments on both monoterpenols and aglycons from the bound forms, showed a good separation among the groups as weil a good homogeneity and varietal correspondence of the wines. K e y w o r d s : aroma compounds, monoterpenols, bound forms, Galician wines, classification. lntroduction to the Portuguese border - and 1 Godello) obtained with the same technology in the experimental cellar of the Particular attention has been devoted in the last years Oenological Institute of Leiro, Spain, were analyzed in to the analytical characterization and to the quality im July and August 1993. provement, especially through the skin-contact technique, All samples, added with 250 1-1-g/l of 2-octanol as inter of the varietal aroma of certain white wines from the north nal standard, were submitted to a 10 h liquid-liquid aroma west region of Spain, mainly of Albariiio and Loureira extraction with pentane-dichloromethane, 2:1, v/v, (quan cultivars, both typical for a floral note (ORTEGA liERNAN tification of most volatiles, in particular more polar fer oEz-AGERO et al. 1991; ÜRRIOLS and MoRENO CAMACHO 1992; mentation products; 350 ml wine with 50 ml organic sol PEREZ FERNANDEZ et a/. 1992; GARCIA JARES et a[. 1993). vent - DRAWERT and RAPP 1968) and to a fractionation An interesting presence of linalool in a concentration (100 ml wine) on XAD-2 resin of the free and bound aro of 20-50 1-1-g/l for Albariiio musts and approximately 5-8 ma parts (according to GUNATA et al. 1985) modified by times more for Loureira musts was found. This compound percoling the free forms with pentane/dichloromethane, contributes to the sensorial difference between the two 2:1, v/v (90 ml), and the bound with ethyl acetate/methan products; the content of other monoterpenols like a.-terpi ol, 9:1, v/v (80 ml), (VERSINI et al. 1993 a). Among the free neol, geraniol, nerol and citronellol resulted not higher than forms from XAD-2 enrichment, only the monoterpenols 10-20 ~-tg/1. Godello and other monovarletal Galician wines were quantified. The bound fraction, concentrated to dry seem not to show any marked monoterpenic content and ness, reacted for 12 h at 40 oc with Rohapect C enzyme character (ORRIOLS et al. 1993). (Röhm, Darmstadt) in 3 ml citrate buffer at pH 5, then In this research on the aroma components of wines of added with the same internal standard and extracted three the mentioned varieties, we focused the attention princi times with 3 ml pentane/dichloromethane. pally to compounds possibly linked to varietal peculiari All compounds from XAD-2 fractionations were quan ties, extending in particular the investigation to other tified as 2-octanol, except for the diols evaluated as 2,6- monoterpenols and to the bound forms, with the aim to dimethyl-3, 7-octadiene-2,6-diol (ho-diendiol I). improve the characterization and classification of the wines. Gas chromatographic analyses: Methanol, higher alcohols, acetaldehyde and ethyl acetate were determined with a packed column by injection of the Materials and methods 1:1 distillate of the wine at pH 7 (SALVAGIOTTO et al. 1981). Detailed GC and GC-MS analytical conditions for aro 11 Albariiio and 6 Godello wines of 1992 vintage, avail ma extractes were reported previously (VERSINI et al. 1988). able on the market, and varietal products (3 Albariiio, 2 Some monoterpenols, above all those present in very small Loureira - representative of a small production area close quantities or those for which the relevant peaks are not Correspondence to: G. VERSINI, Laboratorio di Analisi e di Ricerca, Istituto Agrario di San Micheie all' Adige, 38010 San Micheie all'Adige (Trento-Italy). 166 G. YERSINI, I. ÜRRIOLS and A. DALLA SERRA well resolved from others as often happens for trans and nologically well elaborated young fruity products, is con cis furan and cis pyran linalool oxides, nerol, 2,6-dime sidered in relation to the variety denomination category of thyl-1,7-octadiene-3,6-diol (ho-diendiol II) and trans and wines. The significance of the discrimination Ievel on the cis 2,6-dimethyl-2, 7 -octadiene-1 ,6-diols (8-hydroxylin~ basis of the Tukey test, is also reported, taking into ac lool) under free forms, were quantified by happens GC count for such comparison, in few cases, a more homoge SIM/MS analysis, integrating specific ions and relating the neous subgroup of values purged from some outliers. values to those corresponding to other compounds found Among the discriminating compounds and particularly also by FID-GC. those having values depending to a lower extent on fer In particular, all oxides were related to the trans pyran mentation conditions and that are almost unchanged dur linalool oxide, the nerol to the geraniol and the ho-diendi ing ageing, we would like to give prominence to the dif ol II, as weil as the 8-hydroxylinalool isomers to ho ferences in trans and cis 3-hexen-1-ol and methanol con diendiol I. tents. Statistkai evaluation of the data was carried out by The Albarifio products prove to be characterized by a using SAS package. higher Ievel of cis than of trans 3-hexen-1-ol. This fact has also been verified in 5 commercial Albarifio wines from 1987, '88 and '89 vintages, but only at times in the Iitera Results and discussion ture (ÜRRIOLS and MoRENO CAMACHO 1991, 1992). At vari ance, the Loureira and, except for one case, the Godello Volatile compounds, except monoterpenols. In wines, present a more marked trans isomer, a tendency Tab. 1, the concentration variability of the compounds, already found for ltalian Soave wines obtained from the which ranges generally within an interval typical for tech- Garganega variety (MORET et al. 1987), for Traminer Table 1 Volatile cornpounds, except for rnonoterpenols, in Galician wines. For each variety the nurnber of sarnples, the rnean content (x) and the standard deviation (cr) for each cornpound are reported; in few cases outliers or rninority subgroups are evidenced. Possibly, the cases of significant (> 95 %) differences between the groups on the basis of the Tukey test, are indicated by using different letters in the right colurnns, each one referred to the cited varieties: A =Albariiio, G =Godello, L =Loureira COMPOUND (mgn) ALBARIND (14) GODELLO (7) LOUREIRA (2) A G l X u X u X u METHANOL 34.51:1 4.86 21.3' 5.60 19.5 2.79 • b b 62.5' 11.81 43.41 7 .32 1·PROPANOL 22.6 9.43 17.9 3.48 32.1 8.56 2·METHYL· 1·PROPANOL 28 .1 11.41 27.4 5.73 32.9 14.57 1·BUTANOL 1.72 0 .501 1.76 0 .331 1.75 0 .354 2·METHYL·1·BUTANOL 23.7 5.38 27.3 3.83 19.1 1.27 3·METHYL-1-BUTANOL 148.7 26.66 149.2 19.30 78.9 3 .04 a a b 1·HEXANOL 1.14 0.672 1.57 0.512 0.867 0.1732 trans 3-HEXEN-1 -0L 0.044 0.0169 0.124 0.0531 0.039 0 .0021 • b • cis 3-HEXEN-1-0L 0.130 0 .0298 0 .094 0.0237 0.016 0.0021 • b c trans I cis 3-HEXEN-1 -0l 0.344 0 . 1302 1.56' 0 .436 2.52 0.481 • b c 0 .361' BENZVL ALCOHOL 0.050 0.0256 0 .079 0.0327 0.010 0.0000 ab a b 2·PHENYLETHANOL 17.7 4.42 20.2 8.59 11.1 2.93 3·METHYL·1·PENTANOL 0.040 0.0232 0.033 0 .0151 0.010 0 .0000 10 3·ETHOXY·1·PROPANOL 0.29 0.193 0.34 0 .291 3.7 1.43 8 8 b 5.5• 1.42 3·METHYLTHI0.1·PROPANOL 1.35 0.723 1.64 1.125 1.83 0 .287 ACETALDEHYDE 50.6 24.54 52.9 26.48 13.0 2.05 BENZALDEHYDE 0.00511 0.0037 0.024' 0.0079 0.006 0.0040 a b a 0.0532 0.0329 0 .260' ETHYL ACETATE 56.5 30.78 35.7 11.85 41.3 1.77 10 1.3·PROPANEDIOL MONOACETATE 0.70 0 .