Wine chemical composition

Because of the high variability of yeast species and their population sizes, and the difficulty in microbial profiling of fermentation, few studies have reported on wine chemical composition (Beh et al. 2006). General characteristics are recorded in Table 8D.5. These data suggest that the diminished role of Saccharomyces allows some of the mn-Saccharomyces characteristics to be more evident and to... 

The published literature on the effects of microbial activities on wine chemical composition is now considerable. Understanding the significance of wine chemistry is, however, heavily dependent on complex analytical strategies which combine extensive chemical characterization and sensory descriptive analysis. However, sensory analysis is extremely resource-intense, requiring many hours of panelists time. This prevents widespread application of these powerful analytical tools. Advanced statistical techniques have been developed that are closing the gap between chemical and sensory techniques. Such techniques allow the development of models, which should ultimately provide a sensory description based on chemical data. For example, Smyth et al. (2005) have developed reasonable models which can reveal the most likely compounds that relate to particular attributes that characterise the overall sensory profile of a wine. For wines such as Riesling and Chardonnay, the importance of several yeast volatile compounds has been indicated. Such information will allow yeast studies to target key compounds better rather than just those that are convenient to measure. 

Food chemistry Foods (oils, wines, ) Chemical composition Crops... 

Neural networks are extensively used to develop nonparametric models and are now the method of choice when electronic noses are used to analyze complex mixtures, such as wines and oils.5 Judgments made by the neural network cannot rely on a parametric model that the user has supplied because no model is available that correlates chemical composition of a wine to the wine s taste. Fortunately, the network can build its own model from scratch, and such models often outperform humans in determining the composition of oils, perfumes, and wines. 

In Roman times tar and pitch from Pinaceae resinous wood were used to treat the inner surface of amphorae to store fluids such as wine [ 145,149] and to seal ship planks [89,144], Heating treatments applied to natural resins and resinous wood profoundly modify the chemical composition of the original material. Diterpenoid compounds undergo aromati-zation, demethylation and decarboxylation reactions, with the formation of new compounds of a lower molecular weight that show a high degree of aromatisation [87,88]. In tar and pitch produced from Pinaceae resin and woods, retene is considered as a stable end product of these reaction pathways and nor-abietatrienes, simonellite and tetrahydroretene represent the intermediates of these reactions [87,89,150]. 

From the point of view of the chemist, champagne can indeed be viewed as a multicomponent aqueous solution. The chemical composition of a typical Champagne wine is reported in Table 1.2 (Dussaud, 1993). 

The overall chemical composition of brandy is derived from four general sources the fruit, alcoholic fermentation, distillation, and aging in wood. The scope of this discussion is limited to chemical aspects of the components of wine and their behavior during distillation. 

IV. CHANGES IN THE CHEMICAL COMPOSITION OF SHERRY WINES DURING THE BIOLOGICAL AND OXIDATIVE AGING... 

In a more recent study, Lencioni et al. (2009) reported the chemical composition and perceivable characteristics of wine obtained under ambient conditions (vinsantaia) with and without addition of madre and using different strains of S. cerevisiae. It was found that the different S. cerevisiae strains showed different fermentation behaviors and produced wines with different compositional and organoleptic characteristics. In particular, by the fermentations conducted with madre addition it was reached... 

Romani, C., Lencioni, L., and Domizio, P. (2009). Chemical composition and organoleptic characteristics of Vinsanto wine obtained by using different Saccharomyces strains. Ann. Microbiol. 59(Special Issue), 76. 

These results suggest that non-Saccharomyces species may contribute significantly to the fermentation of botrytized wines. C. zemplinina seems not to produce excess volatile compounds nor any specific aroma compounds (Toth-Markus et al., 2002). Its main contribution to the chemical composition might be an increase in glycerol content and in the G F ratio. C. zemplinina and C. stellata have proven to be very fructo-philic yeasts (Mills et al., 2002 Magyar and Toth, 2011 Magyar et al., 2008). 

The unique chemical composition of botrytized must greatly impacts the products and by-products of alcoholic fermentation, as well as subsequent reactions. The changes have been extensively studied by German and French authors and have been reviewed by Dittrich (1977, 1989), Jackson (2008), Ribereau-Gayon et al. (2000), and Dittrich and Grossmann (2011). The chemical composition of some traditional (German and Hungarian) botrytized wine styles are illustrated in Table 6.5. 

TABLE 6.5 Chemical composition of some traditional botrytized wines from France, Germany, and Hungary... 

W. O. Kwan, B. R. Kowalski, Classification of wines by applying pattern recognition to chemical composition data, J. Food Sci., 43 (1978), 1320-1323. 

The red liquid or red wine is also purified by gentle distillation. First, a clear acidic phlegm will come over. The thick blood-red oil that remains can be distilled at a higher temperature or often it is just dissolved in alcohol and the clear tinted liquid is decanted for use. These oils are analogous to the essential oils obtained from plants and their chemical composition is just as complex. 

Most of the studies published in the literature on sparkling wine quality are aimed at establishing the effect of the chemical composition of these wines and the different technologies used in their production on their foaming qualities. 

Pueyo, E., Martfn-Alvarez, P.J., and Polo, M.C. (1995). Relationship between foam characteristics and chemical composition in wines and cavas (sparkling wines). Am. J. Enol. Vitic., 46, 518-524. 

Aznar, M., Lopez, R., Cacho, J., Ferreira, V. (2003). Prediction of aged red wine aroma properties from aroma chemical composition. Partial least squares regression models. J. Agric. Food Chem., 51, 2700-2707. 

In a recent study, using multivariate statistical analysis of quantitative sensory descriptive analysis and precise chemical compositional data, Smyth et al. (2005) found that the importance of individual yeast esters to the aroma profile of wine can vary with the type of wine. In the case of unwooded Chardonnay wines, for... 

Table 8D.5 A generalized chemical composition of wine made with indigenous yeasts...

EgUnton, J. M., McWilUam, S. J., Eogarty, M. W., Erands, 1. L., Kwiatkowski, M. J., H0j, P. B., Henschke, P. A. (2000) The effect of Saccharomyces bayanus-mediaHtd fermentation on the chemical composition and aroma profile of Chardonnay wine. Australian Journal of Grape and Wine Research, 6, 190-196. 

Gawel, R., Francis, L., Waters, E. J. (2007a) Statistical correlations between the in-mouth textural characteristics and the chemical composition of Shiraz wines. Journal of Agricultural and Food Chemistry, 55, 2683-2687. 

Ethanethiol has a very weak perception threshold (1.1 p-g/L) according to Goniak and Noble (1987), and has never been detected in wines without reduction defects. In some of the wines with a very high H2S concentration (estimated at around 20 pg/L), the ethanethiol concentrations are very low (lower than 2 pg/L). Also, concentrations in some white wines are higher than those found in red wines (Lav-igne 1996). The very different chemical composition of a white wine compared to a red wine (especially in relation to the presence of phenolic compounds) could explain the difference in results. On the other hand, no author has demonstrated the formation of ethanethiol from H2S, ethanol or ethanal in a red wine. 

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