Dataset of volatile compounds identified, quantified and GDA generated of the maturation process of silver tequila in new French oak barrels

This article contains data obtained by following the evolution of minor volatile compounds throughout 32 weeks of 100% Agave Silver tequila maturation in new French oak barrels under real cellar conditions. Barrels were made with the same cooperage methods in four French regions. Tequila samples were obtained every 2 weeks; volatile compounds were extracted and analyzed by GC-MS. Volatile compounds were identified and relatively quantified in % of Area. Obtained data are presented in three datasets: Identified compounds, quantification according to barrel origin, and quantification according to maturation time. General Discriminant Analysis of the quantification data sets are also shown. Interpretation of the data and discussion can be found in “Evolution of volatile compounds during the maturation process of Silver tequila in new French oak barrels” Martín-del-Campo, López-Ramírez and Estarrón-Espinosa [1].


Data
Data presented correspond to the minor volatile compounds identified in Tequila samples at different maturation time (weeks) and according with the oak barrels origin region (Table 1) as well as the relative mean concentration of volatile compounds (% area) according with barrels origin (Table 2) and maturation time (Table 3). Additionally, General discriminant analysis classification tables, test of significance of Squared Mahalanobis distances, and statistics for each tequila sample are presented according to barrel origin (Tables 4e6) and maturation time (Tables 7e9). All the presented data are related to a research article in press [1].

Tequila samples
Tequila samples were obtained as described before [2]. One batch of 100% Agave Silver tequila directly obtained from distillation stage, 40% alcohol v/v, provided by a Tequila company (Jalisco, M exico) was placed in new oak barrels with a capacity of 230e240 L of 4 different French regions: Allier (Region I, RI), Limousin (Region II, RII), Tronçais (Region III, RIII), and Centre de la France (Region IV, RIV) ( Fig. 1). All the oak barrels were made with the same cooperage method and were conditioned at the origin with medium intensity toasting (no more data were provided for the distillery). Four barrels from each region (n ¼ 16) were filled with the tequila and maturated in the Tequila's company cellar

Value of the Data
This data shows a comprehensive list of volatile compounds identified in Tequila samples maturated in French oak barrels from four regions and at different maturation times. A total of 173 minor volatile compounds were identified; they belong to different chemical families. This list is the most extensive list of volatile compounds identified in tequila samples throughout the maturation process. Data sets about volatile compounds quantification according to the barrel origin and maturation provide information about abundance and evolution of the different compounds and chemical families and associate them with the barrel origin and the maturation time.
General discriminant analysis of the volatile compounds quantification data is useful to show the impact of changes in the volatile composition to discriminate samples according to the barrel origin and according to the maturation time.
Specifications Table   Subject area Food chemistry. More specific subject area Aroma evolution during Tequila maturation.

Type of data
Tables. How data was acquired GC-MS (HP 5890 Series II coupled to a mass detector HP 5972) with capillary DB-Wax column (Hewlett-Packard). Compounds were tentatively identified with the Wiley 175L spectra library. Identity was confirmed with reference standards and/or by comparison with the Kovats index. Relative quantification was done with the percent area method.

Data format
Processed and analyzed.

Experimental factors
Tequila sample's volatile compounds were extracted by liquid-liquid extraction (Pentane:Dichloromethane 3:1 v/v) and concentrated in a Kuderna-Danish device.

Experimental features
100% Agave silver tequila (just after distillation) was placed in new French oak barrels from four different regions and maturated under real cellar conditions. Samplings were performed from week 2 until week 32 every 2 weeks for each barrel region.

Data source location
Tequila region, Jalisco, M exico.

Data accessibility
Data is with this article.

Related research article
Evolution of volatile compounds during the maturation process of Silver tequila in new French oak barrels (in press) Martín-del-Campo, L opez-Ramírez and Estarr on-Espinosa [1].
(continued on next page)  0 2 4 6 8 10 12 14 16 18 20 22 24 25 28 30 32 I II III IV   3-methylbut-3-en-1-ol  763-32- under darkness (18 ± 5 C and 50 ± 5% of relative humidity). Then, a 1 L sample was obtained from each barrel every 2 weeks until a final time of 32 weeks. Samples for each region at each sampling point were homogenized given one batch of 4 L for each region and sampling point. This method was selected instead of having 4 Â 1 L samples since in Tequila's distilleries tequila from barrels filled with the same batch is mixed to obtain a homogeneous final product.

Volatile compounds analysis
Minor volatile compounds were extracted according to the methodology reported before [3]. First, the sample's alcohol content was adjusted to 30 mL of ethanol/100 mL by adding distilled water and ethanol content was verified with calibrated alcoholometer (Dujardin-Salleron, Paris) with the Gay-Lussac scale at 15 C. Then 0.2 g of NaCl (A.C.S. J.T. Baker, Phillipsburg, NJ) was added to 325 mL of the alcohol adjusted sample and volatiles were extracted with 45 mL of a mixture of pentane/ dichloromethane 3:1 (v/v) (HPLC, Fisher, Leicester, U.K.). After 5 min agitation, was let to stand until   organic layer complete separation. The organic layer was recovered and dried with anhydrous Na 2 SO 4 (Mallinckrodt, Paris, USA). Extracts were concentrated in a Kuderna-Danish device until a final volume of 0.4 mL, placed in suitable tight closed vials and kept at À40 C until analysis. All the samples were extracted twice.

Gas chromatographic analysis (GC-MS)
Extracts were analyzed twice by gas chromatography in a gas chromatograph HP 5890 Series II (Hewlett-Packard, Palo Alto, USA) coupled to a mass detector (HP 5972), with a capillary DB-Wax polyethylene glycol column (30 m Â 0.25 mm ID Â 0.25 mm thickness, Hewlett-Packard). The oven program was 40 C, 5 min, then increased at 2.5 C/min until 220 C and held for 35 min. Injector and detector temperatures were kept at 220 C and 260 C, respectively. A sample volume of 0.5 mL was automatically injected using helium as carrier gas at 0.8 mL/min and a 60:1 split ratio was used. The total ion chromatograms (TIC), as well as the mass spectra, were acquired in the electron impact (EI) mode at 70 eV and traced at 1.6 scans/s. Compounds were tentatively identified by comparing the spectrum of each compound with the Wiley 175L spectra library. Identity was confirmed by comparing with reference standards (Sigma-Aldrich, St. Louis, MO, USA) with a purity >98% and/or by comparison with the Kovats index reported in the literature and by consulting bibliographical references of tequila and other spirits whose volatile composition has been studied in columns similar to the one used in the methodology of this study.
The quantification was performed with the percent area quantification method after subtraction of solvents area. This method was selected because chromatograms were too complex to add an internal standard.