Metallic profiles of Sherry brandies
Ana M. CAMEÁN1 *, Isabel M. MORENO1, Miguel LÓPEZ-ARTÍGUEZ2, Manuel REPETTO1, 2, Antonio G. GONZÁLEZ3
RÉSUMÉ Teneurs en métaux des eaux-de-vie de Xérès.
Différentes techniques de spectrométrie atomique ont été appliquées au dosage des métaux dans 20 échantillons d’eaux-de-vie de Xérès. Le calcium, le cuivre, le fer, le manganèse et le zinc ont été dosés par spectrométrie d’ab- sorption de flamme ; le potassium et le sodium par spectroscopie d’émission atomique ; l’arsenic par spectrométrie d’absorption atomique avec génération d’hydrure ; l’aluminium, le calcium et le plomb par spectrométrie d’absorption atomique avec atomisation électrothermique. Sans exception, les teneurs en métaux (Zn, Cu, As et Pb) restent dans les limites fixées par la norme espa- gnole. Les concentrations en métaux dans nos échantillons d’eaux-de-vie sont inférieures à celles trouvées dans les vins de Xérès, sauf pour Cu et Na. Par ailleurs, les teneurs en Ca et K semblent augmenter avec l’âge de l’eau-de-vie.
Rapportés à la consommation d’eau-de-vie, les résultats analytiques montrent que celle-ci ne contribue pas de façon significative à l’apport alimentaire des métaux dosés.
Mots clés : métaux, eau-de-vie, spectrométrie atomique.
SUMMARY
Twelve elements, namely, aluminium, arsenic, calcium, cadmium, copper, iron, lead, magnesium, manganese, potassium, sodium and zinc were determined in 20 samples of Sherry brandies by applying atomic spectrometry techniques.
Flame atomic absorption spectrometry was used for quantification of calcium, copper, iron, magnesium, manganese and zinc; atomic emission spectrometry for potassium and sodium determination; hydride generation atomic absorption spectrometry for arsenic quantification; and graphite furnace atomic absorption spectrometry for aluminium, cadmium and lead analysis. In all cases, metal contents (Zn, Cu, As and Pb) met the guidelines established by the Spanish
1. Departamento de Bioquímica, Bromatología y Toxicología, Facultad de Farmacia, calle Prof. García González s/n, Universidad de Sevilla, 41012-Sevilla, Spain.
2. Instituto Nacional de Toxicología, Departamento Regional de Sevilla, PO Box 863, 41080-Sevilla, Spain.
3. Departamento de Química Analítica, Universidad de Sevilla, 41012-Sevilla, Spain.
* Correspondence and reprints camean@ fafar.us.es
regulations. The content of these metals was lower than in Sherry wines, with the exception of Cu and Na. The content of Ca and K increased with brandy aging. As a result of this study of the metallic profiles of Sherry wines and Sherry brandies, and due to the minor consumption of the latter drink, we can suggest that they make no significant contribution to the total intake of these elements for normal drinkers.
Key-words: metal, brandy, spectrometry.
1 - INTRODUCTION
Metal quantification in brandies is a very interesting topic because the metal- lic profile, at both minor and trace levels, is of outstanding importance in the evaluation of brandy quality (BELLANATOand BRAVO-ABAD, 1988).
Brandy is defined, according to Spanish regulations (Real decreto 2484, 1974) as a complex spirituous beverage, issued from wine distillates, and matu- rated in oak casks under adequate environmental conditions for a suitable per- iod of time, in order to achieve the organoleptic features peculiar to the elaboration process.
Sherry brandy is a liquor elaborated from quality wines (12-13 vol ethanol) coming from stocks of the varieties Airen Blanca and Palomino. An initial distilla- tion of these wines yields “holandas” which is then aged according to the Solera system of Jerez using oak casks which have previously been employed to mature Sherry wines. After a period of time (between 5-25 years), the resulting product is Sherry brandy, with an alcoholic content ranging from 37º-45º vol ethanol (Ministerio de Agricultura, Pesca y Alimentación, 1989). The aging of Sherry brandies must be carried out in warehouses located within the triangle whose corners are the cities of Jerez de La Frontera, El Puerto de Santa María and Sanlúcar de Barrameda. This requirement comes from the capital role played by the micro-climate found in these environments (MUÑOZ RAMOS, 1996).
The origin of the source wine, as well as the brandy elaboration procedure, influence the metallic profile of the brandies as a consequence of intermediate processes such as fermentation, maturation and aging of the wines and the way in which the distillation is performed to obtain the brandy.
The human consumption in Spain of spirituous alcoholic beverages such as brandy, rum, ginger, whisky, etc., has increased by about 29% over the last four years, with an average increment of 7% per year (MAPA, 1991). This is perhaps a consequence of the spreading fashion for long drinks. Therefore, a knowledge of the metal content in these beverages may serve as an indicator of possible toxic exposure in high consumers. Since exact data on brandy consumption is unavailable, a coarse estimation of about 10 L/person/year of spirituous beve- rages has been put forward (MAPA, 1991).
The aim of the present paper is to determine the metallic profile of a number of samples of genuine Sherry brandies with the D.O. trademark, in order to cha- racterise them and to evaluate human exposure.
2 - MATERIALS AND METHODS
2.1 Apparatus
A Perkin Elmer 3100 (Perkin Elmer Corp., Norwalk, CT) atomic absorption spectrometer was used to quantify calcium, copper, iron, magnesium, manga- nese and zinc by using Flame Atomic Absorption Spectrometry (FAAS), and potassium and sodium by Atomic Emission Spectrometry (AES). This equipment was adjusted to a PE MHS-10 hydride generator in order to determine the total arsenic content from hydride generation atomic absorption spectroscopy (HG- AAS). A Perkin Elmer 1100B atomic absorption spectrometer fitted to a Perkin Elmer HG-500 graphite furnace and a Perkin Elmer AS-40 automatic injector was employed to determine aluminium, cadmium and lead by the technique of Gra- phite Furnace Atomic Absorption Spectrometry (GFAAS). Experimental condi- tions for metal determination are shown in table 1. GFAAS temperature programs for determining aluminium, cadmium and lead are presented in table 2.
Table 1
Experimental conditions for the determination of mineral elements Element Wavelength Linear range Dilution range
(nm) (mg·L–1) (v/v)α
Al 309.3 0.002 - 0.150 up to 1/10
As 193.7 0.0015 - 0.060 1/10
Ca 422.7 0.3 - 5.0 up to 1/100
Cd 228.8 0.0002 - 0.0100 no dilution
Cu 324.8 0.08 - 0.50 no dilution
Fe 278.3 0.25 - 0.50 no dilution
K 766.5 0.078 - up to 1/100
Mg 285.2 0.07 - 0.50 up to 1/100
Mn 279.5 0.02 - 2.00 no dilution
Na 589.0 0.14 - up to 1/500
Pb 283.3 0.0005 - 0.1000 1/3
Zn 213.9 0.06 - 1.00 no dilution
αDiluted with ethanol 40% v/v.
Table 2
HGA 500 graphite furnace parameters used for analysis of Al, Cd and Pb in brandies.
Argon flow rate: 300 mL/min; injection volume: 20 µL; spectral bandwith 0.7 nm Step Temperature (ºC) Ramp (s) Hold (s)
Al Cd, Pb
1 80 80 5 15
2 100 100 5 15
3 600 1400 5 15
4 1600 2400 0 3a
5 2500 2500 1 1
6 20 20 5 5
agas stopped for reading.
2.2 Reagents and solutions
Aluminium metal, calcium carbonate, cadmium metal, copper metal, iron wire, lead metal, magnesium ribbon, manganese metal, potassium chloride, sodium chloride, zinc metal and arsenic (III) oxide of analytical reagent grade (E. Merck, Darmstadt, Germany) were used for preparing stock solutions of about 1000 mg·L–1 following the Perkin Elmer guidelines. Sodium borohydride (Merck, analytical reagent grade) 1.4% (w/v) in 1M sodium hydroxide solution was employed to generate the arsine. Other reagents were of reagent grade or better. Milli-Q treated water (Millipore Corp., Bedford, MA) was used throu- ghout. The working solutions were prepared by suitable dilution from the cor- responding stock solutions with 40% v/v ethanolic solution.
2.3 Samples
Twenty samples of Sherry brandies of different brands with the D.O. trade- mark were purchased at three different points of sale (liquor retailers and mar- kets). The alcoholic degree ranged from 35º-40º v/v ethanol. Once opened, the bottles were capped with our own corks and were stored in a cupboard at room temperature. Aliquots of brandies were used without prior treatment for prepa- ring the assay solutions to be analysed. These assay solutions were the pure liquor for the determination of copper, iron, manganese and zinc. Otherwise, suitable dilutions with 40% v/v ethanolic solution were performed as indicated in table 1.
2.4 Analytical procedures
Brandies were diluted as required in order to obtain suitable read-outs which allowed precise quantification. Ca, Cu, Fe, Mg, Mn and Zn were determined by FAAS, Na and K, by AES and Al, Cd and Pb by GFAAS. Sample dilution and linear concentration ranges for each element are shown in table 1, and the tem- perature programs for the GFAAS determinations are indicated in table 2. Linear concentration intervals for each element range between the detection limit (in concentration units) and a value, which is less than or equal to the maximal concentration, recommended in the Perkin Elmer Guidelines. All elements with the exception of As, were determined from external calibration, by matching the alcoholic content in the samples and in the calibration standards. Arsenic was quantified following the standard addition method (GUERRERO et al., 1996) to avoid undesirable matrix effects.
3 - RESULTS
The metal content of the different Sherry brandies is shown in table 3. All the results were expressed in mg of metal per Litre of brandy, and are the average of triplicate measurements. These results were rounded up to the last significant figure associated with random error. As can be seen, the content of some alka- line and alkaline-earth metals (Ca, Mg, K and Na) is very variable in different
sherry brandies, whilst some trace metals such as Zn and Mn cannot be detec- ted in several brands.
According to the Spanish regulations (Real Decreto 2484, 1974) the total contents of Zn + Cu and As + Pb must not exceed 40 mg·L–1and 1 mg·L–1, res- pectively. In both cases these requirements were always met.
4 - DISCUSSION AND CONCLUSIONS
The results obtained are in agreement with the small amount of data which has been previously reported in the literature. For example, BELLANATO and BRAVO-ABAD(1988) found the following ranges for eleven samples of Spanish brandy: 12-198 mg·L–1of K; 20-116 of Na and 2-11 of Ca. In our study (Sherry brandies only), without including samples in which the metal was not detected, the corresponding ranges were: 0.1-70.1 mg·L–1of K; 17.8-419.9 of Na and 0.8- 14.8 of Ca. Although the differences in sample size as well as in the brandy ori- gin does not permit a full comparison to be made, the previously reported intervals overlap with those obtained in this work, indicating an agreement in the order of the metal content. Data on K and Ca for Sherry brandies have been recently published (MUÑOZ RAMOS, 1996) giving intervals of 11-92 mg·L–1for K and 3.0-11.5 for Ca, which agree well with our data. Furthermore, it was clai- med that these contents increase with brandy aging. In support of this, the samples in our study which possessed higher contents in Ca and K correspon- ded to brandies matured for at least three years (Solera Gran Reserva).
CABRERA et al. (1995) reported the contents of some other trace metals in the most widely consumed brandies in Andalucía. Thus, the following average levels were determined: 0.28 mg·L–1of Fe, 0.48 mg·L–1of Cu, 0.27 mg·L–1of Zn and 0.003 mg·L–1 of Mn. In our study, the ranges obtained were: 0.32-2.03 mg·L–1 of Fe, 0.22-5.31 mg·L–1 of Cu, 0.118-0.829 mg·L–1 of Zn and 0.021- 0.157 mg·L–1of Mn. With the exception of Mn, our intervals contain the average levels reported by CABRERAet al. (1995). Nevertheless, this comparison, again, should be considered with caution for two reasons: On one hand, the cited authors did not clearly state the number of brandy samples analysed and on the other hand, these average values were determined with inclusion of negligible (not detected) data.
Compared with the metallic profile of Sherry wines (LÓPEZ-ARTÍGUEZ et al., 1996), Sherry brandies exhibit lesser contents for all the metals analysed with the exception of Cu and Na. This fact can be explained by considering the metallic nature of alembics (alquitaras) in the case of Cu. Na, on the other hand, could be incorporated into the brandy during maturation in oak casks.
In comparison with another spirituous beverage, like whisky (SCHOENEMAN and DYER, 1973; SCHOENEMANet al., 1971), the metal content of Sherry bran- dies presents higher values for alkaline and alkaline-earth metals and Fe; and similar values for Cu, Pb and Zn.
Table 3 Experimental resultsafor determination of elements (mg·L–1) in Sherry brandies by FAAS, ESA and GFAAS Sample AlAsCaCdCuFeKMgMnNaPbZn 10.580.01513.20.0083.111.0612.712.830.113122.30.0610.118 20.180.0084.00.0040.700.401.532.15ND161.80.022ND 30.09ND2.50.0050.460.409.370.80ND111.50.039ND 40.090.0101.60.0040.34ND0.930.30ND111.10.041ND 51.140.02714.80.0402.591.7831.207.990.157419.90.3130.676 60.190.0137.90.0040.880.543.694.14ND105.00.034ND 70.380.02013.40.0071.470.8127.300.180.06978.90.2240.289 80.200.0144.20.0071.400.483.560.73ND127.70.042ND 90.16ND3.50.0061.450.453.000.460.02496.80.059ND 100.150.0083.40.0020.300.405.782.44ND635.00.024ND 110.210.0164.10.0061.10ND8.501.25ND26.40.044ND 121.370.02014.00.0095.312.0350.3911.200.124224.20.0730.829 130.020.0160.80.0020.360.320.110.19ND17.80.040ND 140.800.0109.10.0012.461.2037.352.560.09783.90.0290.253 150.200.0083.60.0010.22ND7.740.690.02138.20.026ND 161.000.006ND0.0010.800.7138.522.800.054141.10.0260.152 171.00NDND0.0010.580.807.311.410.032249.40.0150.137 180.50ND1.7ND1.62ND6.280.340.03243.90.008ND 190.80NDND0.0021.770.6270.062.24ND60.60.0180.206 200.30ND3.30.0011.19ND5.230.57ND43.00.022ND ND: not detected. aMean of triplicate determinations.
Table 4
Comparison between the estimated averaged metal intake (EAMI) through Brandy consumption and safety limits (SL) (scaled to mg of element /person/week)
Element EAMI SL References
(mg/person/week) (mg/person/week)
Al 0.09 490 ELLENHORN, 1997
As 0.002 1.05* FAO/WHO, 1989
Ca 1.01 —
Cd 0.001 0.49 ELLENHORN, 1997
Cu 0.27 14-21 ELLENHORN, 1997
Fe 0.115 9800 ELLENHORNand BARCELOUX, 1988
K 3.2 21840 ELLENHORNand BARCELOUX, 1988
Mg 0.43 —
Mn 0.007 ?? CAMEÁNet al., 1998
Na 28 —
Pb 0.01 0.9 ELLENHORNand BARCELOUX, 1988
Zn 0.025 —
* As inorganic species
Finally, in order to allow some discussion about the metal intake through Sherry Brandy consumption, an average intake of each element/person/week was evaluated from our results by considering the estimated Brandy consump- tion in Spain (MAPA, 1991) and the mean content of the corresponding element.
Comparisons were performed with some safety limits for the studied metals, such as the Provisional Tolerable Weekly Intake (PTWI), Estimated Safe and Adequate Daily Dietary Intake (ESADDI), etc., when available. For the sake of homogeneity, indices were scaled to mg of the element/person/week and are displayed in table 4. Average consumption of Sherry wines and brandies does not significantly expose the drinker to un-safe levels of the metals studied.
Receveid 15 November 1999, accepted 4 May 2000.
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