Wines, acetal acetaldehyde

Torulaspora delbrueckii (anamorp Candida colliculosa formerly Saccharomyces rosei) has a moderate tolerance to ethanol (<12.5 vol.% Table 8D.6) and produces wines which resemble those made with Saccharomyces cerevisiae. Production of higher alcohols is however highly variable and strain dependent. Because this yeast produces comparatively low concentrations of acetic acid, ethyl acetate, acetaldehyde and acetoin, its potential suitability for wine production has been suggested by several studies (Cabrera et al. 1988 Ciani and Ferraro 1998 Herraiz et al. 1990 ... 

One example of autooxidation you have experienced is the room-temperature oxidation of alcohol in wine. Within days and sometimes within minutes of opening a bottle of wine, the taste begins to deteriorate because of autooxidation. This converts the ethanol into acetaldehyde and to acetic acid, both of which taste bad. Wine lovers talk about letting the wine breathe after opening so apparently some oxidation actually helps the taste. Distilled vinegar is made by the intentional oxidation of the alcohol in fermented apple juice into acetic acid, which can then be distilled from the juice and pulp. 

During the production of recovery flavours, apple wines or brandies, the interaction with ethanol, acetaldehyde and acetic acid represents the next level of interactions. The reaction products contain compounds which result from esterification and acetal formation reactions, which are summarised in Table 21.4. 

Rankine (6, 38) believes that the differences in the secondary products formed in wines during fermentation by various yeasts are quantitative rather than qualitative, and careful selection of pure yeast strains can eliminate wine disorders caused by large amounts of undesirable by-products such as hydrogen sulfide, mercaptans, acetaldehyde, acetic acid, ethyl acetate, higher alcohols, etc. 

Aldehydes and Other Low-Boiling Components. As mentioned, a low-boiling fraction, called heads, is normally taken from the vent condenser during the distillation of wine into brandy. The principal impurities removed are acetaldehyde, diethyl acetal, ethyl acetate, and acetalde-hyde-sulfurous acid. 

For the richness of the volatile compounds, as would be expected for a wine with oxidative aging, the ethyl acetate in all Vin Santo is generally well represented (mean content, about 250 mg L-1). Acetoin is sometimes high (up to 10 mg L 1), while the acetaldehyde content is almost always... 

Silva Ferreira, A. C., Barbe, J. C., and Bertrand, A. (2002). Heterocyclic acetals from glycerol and acetaldehyde in port wines Evolution with aging. ]. Agric. Food Chem. 51,4356-4363. 

Acetaldehyde takes part in a number of reactions during the biological aging of wine one of the most important of which is the formation of 1,1-diethoxyethane. This acetal results from the combination of acetaldehyde and ethanol. Its concentration, which is closely related to those of the parent compounds, can easily exceed 100 mg/L (Munoz et al. 2005). Also, 1,1-diethoxyethane is the only acetal contributing to the aroma of wine (Etidvant 1991). 

Hanseniaspora uvarum (anamorph Kloeckera apiculata) is commonly the major yeast present on the grape berry and in musts and juices, but due to low tolerance to ethanol, populations decline quickly in the presence of Saccharomyces cerevisiae. Strains are typically characterised by low fermentative ability and high production of acetic acid, ethyl acetate and acetaldehyde, which render such strains more suitable to vinegar production. Nevertheless, Ciani and Maccarelli (1998) surveyed 37 isolates and found considerable variability, with some strains producing concentrations of these compounds approaching concentrations present in wines made with Saccharomyces cerevisiae (Table 8D.6). Cofermentation fermentation with Saccharomyces cerevisiae can produce wines with an acceptable balance of volatile and non-volatile compounds and sensory scores (Ciani et al. 2006 Jemec and Raspor 2005 Jolly et al. 2003b Zohre and Erten 2002). 

A dilution experiment by SHA-0 indicated acetaldehyde, ethyl acetate, dimethylsulfide and dimethyltrisulfide as further potent odorants in Scheurebe and Gewurztraminer wines. AEDA and SHA-0 yielded the same assessment of 4-mercapto-4-methylpentan-2-one and cis-rose oxide, which are responsible for the odor difference of the two varieties, investigated in this study. It should be mentioned that only one sample of each variety was analyzed and for more generality further investigations are necessary. 

In the same extract (SP II) we found another new compound in wine flavor, 2-methyl-l,3-oxathiane (10). The formation of this heterocyclic sulfur compound with chemical, burnt odor properties can be explained as a mixed acetal of 3-mercaptopropanol with acetaldehyde. 3-Mercaptopropanol, however, is not known as... 

Fig.l Gas chromatographic analysis of white wine sample by fused-silica column poly(ethylene glycol) type (15.00 m X 0.53 mm X 1.00 pm). Chromatographic conditions carrier gas hydrogen (3.6 mL/min) column temperature 40°C (4 min) —> 8°C/min 270°C injector port temperature 250°C detector temperature 300°C. Identity of the selected peaks (1) acetaldehyde, (2) acetone, (3) ethyl acetate, (4) ethanol, (5) ethanol,... 

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