Wines, analyses

More than one hundred papers reporting diverse applications to analyse wines were published until know. The majority of the referred methodologies use the headspace mode (HS-SPME) instead of the direct immersion mode (DI-SPME). In terms of performance, SPME showed comparable results to LLE or SPE. However, SPME is simpler and solvent-free, and uses smaller volumes of sample nevertheless, on the other hand, LLE had the possibility of carrying out simultaneously the extraction of several samples (Bohlscheid et al., 2006 Castro et al, 2008). When the interest is to obtain the maximum information about the volatile fraction of a wine, the coating DVB/CAR/PDMS seem to be the most suitable (Tat et al., 2005). On the other hand, for specific applications, the choice of a suitable solid-phase, depends on the class of compounds be analyzed, e.g. CAR/PDMS for volatile sulphides and disulphides (Mestres et al., 1999), on-fibre derivatization (PA) for the determination of haloanisoles and halophenols (Pizarro et al, 2007). 

Ough, C.S. (1988) Determination of sulfur dioxide in grapes and wines, in Modem Methods of Plant Analysis Wine Analysis, vol. 6 (eds H.F. Linskens and J.E Jackson), Springer-Verlag, Berlin, pp. 342-3. 

More recently, studies of wine and beer have initiated techniques of statistically vaUd sensory analysis. Scientific studies involving wine continue in these areas, building on past discoveries. Natural phenols as desirable dietary components and monitors of storage and aging reactions are currently active fields. Viticultural research, as well as enological, continues to improve grapes and the wines made from them (11). 

Various methods have been developed to eliminate biases which otherwise can skew results. The wines must be presented without identification, although the taster should be told the type of wines (the best strawberry wine should rate very poorly in a Cabernet class). Eor the most informative results, many details of coding, presentation order, repHcation, etc must be considered. The results must be statistically examined to estimate whether or not they could have been obtained accidentally. Statistical analysis is an entire field in and of itself, and wine studies have contributed greatly to its present sophistication, as appHed in the flavor field. 

H. F. Linskens and J. F. Jackson, Wine Analysis, Vol. 6 in Modem Methods of Plant Analysis, Springer Vedag, Berlin, 1988. 

The paper describes the different chemical sensors and mathematical methods applied and presents the review of electronic tongue application for quantitative analysis (heavy metals and other impurities in river water, uranium in former mines, metal impurities in exhaust gases, ets) and for classification and taste determination of some beverages (coffee, bear, juice, wines), vegetable oil, milk, etc. [1]. 

T. Hyotylainen, K. Jauho and M-L. Riekkola, Analysis of pesticides in red wines by online coupled reversed phase liquid clir omatogr aphy with a vaporizer/precolumn solvent split/gas dischar ge interface , 7. Chromatogr. 813 113-119(1997). 

M. Heiraiz, G. Reglero, T. Heiraiz and E. Loyola, Analysis of wine distillates made from muscat grapes (Pisco) by multidimensional gas cliromatography and mass spec-ti ometry , J. Agric. Food Chem. 38 1540-1543 (1990). 

CZE is particularly useful for separating anthocyanin dimers or polymeric anthocyanins. Calvo et al. (2004)" separated 13 anthocyanins by CZE including acylated and non-acylated anthocyanins, pyranoanthocyanins, and flavonol derivatives in wine. Saenz-Lopez et al. (2004)" applied CZE to analyze wine aging (1 to 14 yr) as related to monomeric anthocyanins, anthocyanin derivatives, tannins, and fla-vonols. Bicard et al. (1999)" reported the improved detection sensitivity of anthocyanin chemical degradation analysis by CZE. 

In the wine industry, FTIR has become a useful technique for rapid analysis of industrial-grade glycerol adulteration, polymeric mannose, organic acids, and varietal authenticity. Urbano Cuadrado et al. (2005) studied the applicability of spectroscopic techniques in the near- and mid-infrared frequencies to determine multiple wine parameters alcoholic degree, volumic mass, total acidity, total polyphenol index, glycerol, and total sulfur dioxide in a much more efficient approach than standard and reference methods in terms of time, reagent, and operation errors. 

To detect adulteration of wine. Bums et al. (2002) found that the ratios of acetylated to p-coumaroylated conjugates of nine characteristic anthocyanins served as useful parameters to determine grape cultivars for a type of wine. Our laboratory utilized mid-infrared spectroscopy combined with multivariate analysis to provide spectral signature profiles that allowed the chemically based classification of antho-cyanin-containing fruits juices and produced distinctive and reproducible chemical fingerprints, making it possible to discriminate different juices. " This new application of ATR-FTIR to detect adulteration in anthocyanin-containing juices and foods may be an effective and efficient method for manufacturers to assure product quality and authenticity. 

Lee, J., Durst, R., and Wrolstad, R., AOAC official method 2005.02 total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method, in Official Methods of Analysis of AOAC International, Horowitz, H., Ed., AOAC, Washington, D.C, 2005. 

Sami-Manchado, P. et al.. Analysis and characterization of wine condensed tannins precipitated by proteins used as fining agent in enology. Am. J. Enol. Viticult., 50, 81, 1999. 

Saenz-Lopez, R., Femandez-Zurbano, R, and Tena, M.T., Analysis of aged red wine pigments by capillary zone electrophoresis, J. Chromatogr. A, 1052, 191, 2004. 

Moreira, J.L. and Santos, L., Analysis of organic acids in wines by Fourier-transform infrared spectroscopy, Anal. Bioanal. Chem., 382, 421, 2005. 

---