Volatiles in wine

Fedrizzi, B., Magno, F., Badocco, D., Nicolini, G., and Versini, G. (2007). Aging effects and grape variety dependence on the content of sulfur volatiles in wine. J. Agric. Food Chem. 55,10880-10887. 

Dubemet, M. (1976). Determination automatique of acidite volatile in wines. Conn. Vigne Vin, 10(3), 297-309. 

The majority of volatiles in wines are, however, fermentation compounds, starting with the so-called higher alcohols and going on to important flavouring compounds such acetates as of higher alcohols and the ethyl ester of C4-C10 fatty acids for the fruity scents. The free fatty acids, when in abundance, contribute to the goaty flavour (Meilgaard, 1975). 

Several analytical approaches are employed to quantify sulphur volatiles in wine among them, the headspace procedure, such as the Purge and Trap, and solid-phase microextraction methods, combined with GC coupled to different detectors, was shown to be quite effective (Mestres et al., 2000 Rauhut et al., 1998). Recent papers suggest that the HS-SPME technique, with an improved choice of fiber coating phases, would be one of the more promising approaches for the concurrent measurement of compounds with different boiling points (Mestres et al., 2002 Fang and Qian, 2005). 

Figure 5.12 Temperature effect in the HS-SPME adsorption of the wine CFSV on DVB/CAR/PDMS fiber. (Reprinted from Rapid Communications in Mass Spectrometry 21, Fedrizzi et al., Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid-phase microextraction coupled with gas chro-matography/mass spectrometry, p. 711, Copyright 2007, with permission from John Wiley Sons, Ltd)...

Mestres, M., Busto, O. and Gulasch, J. (2002) Application of headspace solid-phase microextraction to the determination of sulphur compounds with low volatility in wines,/. Chromatogr. A, 945(1-2), 211-219. 

The main volatiles in wines are the higher aliphatic alcohols, ethyl esters, and acetates formed from yeasts during fermentation. Acetates are very important flavors characterized by fruity notes, C4-Ci0 fatty acid ethyl esters manly confer fruity scents to the wine. Other wine aroma compounds are C6 alcohols, such as 1-hexanol and cis- and trans-3-hexen-l-ol, 2-phenylethanol, and 2-phenylethyl acetate. Contents of these compounds in wine are linked to the winemaking processes used fermentation temperature, yeast strain type, nitrogen level in must available for yeasts during fermentation, clarification of wine (Rapp and Versini, 1991). Much literature on the wine aroma compounds was reported in reviews by Schreier (1979) and Rapp (1988). 

In general, SPE provides high recoveries of most fermentative volatiles in wine (80-100%), but requires longer times and is quite solvent consuming. On the other hand, the main advantage of this approach is to allow separation of the fraction of glycoside compounds that can be analyzed as aglycones after an enzymatic hydrolysis. 

Many qualitative and comparative studies of volatiles in wines by HS-SPME were preformed (Favretto et al., 1998 Marengo et al., 2001 Vas et al., 1998 Begala et al., 2002 Demyttenaere et al., 2003 Rocha et al.,2006).The calibration curves of the common volatiles in wines can be calculated because of standards that are commercially available and the method is suitable for quantitative analyses. Alternatively, quantitative GC/MS can be performed by using deuterated standards, for... 

TABLE 5.1. Experimental Conditions for HS-SPME-GC/MS Analysis of Volatiles in Wine (Howard et al., 2005)... 

Figure 5.4. The HS-SPME-GC/MS chromatograms recorded in SIM mode in the analysis of compounds reported in Table 5.5 (a) internal standards (33. d6-DMS, m/z 68 34. DPDS, m/z 108 35. MT, m/z 71 36. M ill, m/z 148), (b) analytes (37. EtSH, m/z 62 38. DMS, m/z 62 39. DES, m/z 75 40. MTA, m/z 90 41. DMDS, m/z 94 42. ETA, m/z 104 43. DEDS, m/z 122 44. ME, m/z 78 45. MTU, m/z 92 46. MTP, m/z 106 47. MTB, m/z 120 48. BT, m/z 135 49. IIMT, m/z 122).The SPME conditions are reported in Table 5.4. (Reprinted from Rapid Communications in Mass spectrometry 21, Fedrizzi et al., Concurrent quantification of light and heavy sulphur volatiles in wine by headspace sohd-phase microextraction coupled with gas chromatography/mass spectrometry, p. 710, Copyright 2007, with permission from John Whey Sons, Ltd.)...

Most of the volatiles in wine, more than 800 compounds, with a total concentration of 0.8-1.2 g/1, has been identified. For the wines Gewurztraminer and Scheurebe, it has been found that the compounds listed in Tables 20.16 are so odor active that they can produce the aroma in each case. This could be confirmed for Gewurztraminer in a model experiment. A synthetic mixture of odor and taste compounds in the concentrations given in Table 20.16 and 20.17 reproduced the aroma and the taste of Gewurztraminer. 

Essential oils are obtained from fmits and flowers (61,62). Volatile esters of short- and medium-chain carboxyHc acids or aromatic carboxyHc acids with short- and medium-chain alcohols are primary constituents of essential oils, eg, ethyl acetate in wines, brandy, and in fmits such as pineapple ben2yl acetate in jasmine and gardenia methyl saHcylate in oils of wintergreen and sweet birch. Most of these naturally occurring esters in essential oils have pleasant odors, and either they or their synthetic counterparts are used in the confectionery, beverage, perfume, cosmetic, and soap industries (see Oils, essential). 

The relative concentrations of the odor-active volatiles in all 19 wines were deter-... 

Etievant, P.X., Volatile phenol determination in wine. J. Agric. Food Chem. 29, 65, 1981. 

Chatonnet, P. et al., Synthesis of volatile phenols by Saccharomyces cerevisiae in wines. J. Sci. Food Agric. 62, 191, 1993. 

Table 10.2 presents a summary of odour qualities, odour thresholds in water, and concentrations of some selected volatile compounds, which are characteristic flavour impact compounds, owing to their typical flavour quality and their rather low odour thresholds. These compounds are not formed during fermentation but originate from the raw material and contribute significantly to the typical flavour of a fruit. The components summarised in Table 10.2 are important compounds in wine and different fruits and are discussed later. 

Acetic acid content is used as a criterion for aerobic bacterial spoilage in wines. We can easily analyze two wines and determine that one has a lower volatile acidity than the other. But by every available standard of product quality judgment, the wine with the higher level of acetic acid may be the superior product. It is no accident that Subpart ZZ, Part 240, Title 26 of the Code of Federal Regulations allows the direct addition of acetic acid to correct natural deficiencies in grape wine. As sanitation practices have improved, the so-called natural acetic acid content diminished, and this has been correlated with lower consumer acceptance in certain cases (2). 

Acid formation Species of Brettanomyces, Hansenula, Pic Ilia, Saccharomyces As a contaminant in wines. Brettanomyces spp. Forms a higher concentration of volatile acids (also isobutyiic and isovaleric acids) than S. cerevisiae. Pichia species and other yeasts are responsible for acetic acid production in brines of domestic green olives not lactobacilli, as assumed for years (Vaughn et al., 1976). 

An example of separation obtained with this method is reported in Fig. 2. Falque and Fernandez (23) study the influence of time of contact with the skins on the composition of the volatile fraction and of the carboxylic acids in wine produced from Treixadura grapes. Also, these authors quantify glycerol and ethanol, besides carboxylic acids and sugars, through the use of an Aminex HPX-87H (300 X 7.8 mm) column, but with the mobile phase of H2S04 0.65 mM at 75°C and a flow of 0.7 ml/min. They use a UV detector at 214 nm and an RI in series. The sample requires only a filtration at 0.45 /im, as described in their survey (24). 

There are more than 550 identified volatile components in wine and most types of terpenoids contribute to wine aroma (79MI59, 83SAJEV49, 89MI584), the origin of which is divided into four classes ... 

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