Wines acrolein

In claret wine turned bitter, Voisenet observed a divinylglycol, CHj=CH-CHOH-CHOH CH=CHj. It is not known which isomer is involved and whether the compound is optically active. The glycol is considered to be derived from acrolein. It could originate either by a reduction comparable to the formation of pinacol from acetone or by bioreduction of an acyloin-like condensation product of acrolein. 

Acrolein has been identified in foods and food components such as raw cocoa beans, chocolate liquor, souring salted pork, fried potatoes and onions, raw and cooked turkey, and volatiles from cooked mackerel, white bread, raw chicken breast, ripe arctic bramble berries, heated animal fats and vegetable oils, and roasted coffee (Cantoni et al. 1969 EPA 1980, 1985 IARC 1985 Umano and Shibamoto 1987). Sufficient data are not available to establish the level of acrolein typically encountered in these foods. Trace levels of acrolein have been found in wine, whiskey, and lager beer (IARC 1985). Further information regarding the occurrence of acrolein in food and related products is provided by EPA (1980). 

The microbiological breakdown of glycerol forms acrolein, a product which causes bitterness in wine by binding with phenolic components (Singleton 1995). Ethanol increases the intensity of the bitter taste, as well as the duration of the bitter sensation (Noble 1994). An increased alcohol concentration resulted in an increase in the bitter sensation (Eischer and Noble 1994). Lactobacillus brevis and L. buchneri, isolated from spoiled wine, can metabolize glycerol in the presence of... 

Glycerol in wine may act as a carbohydrate nutrient for the growth of various microorganisms, e.g. the yeast in Sherry production (Volume 1, Section 14.5.2). Also, certain detrimental bacteria are capable of breaking down glycerol, with a double dehydration reaction that produces acrolein (Figure 2.6). Acrolein interacts with tannins to... 

Thus, if the amino acid (Figure 8.23) is alanine (R3 = -CH3), widely represented in must and wine, the corresponding aldehyde is ethanal. If the amino acid is methionine (R4 = CH3-S-CH2-CH2-), which is certainly only present in small quantities but is reputed to be highly reactive with carbonylated compounds, then methional, or -methyl-S-propanal, is produced. This compound is thermally unstable and evolves rapidly, via a Retro-Michael reaction, into acrolein and methanethiol (Figure 8.28). These smell of cooked cauliflower, wet dog, etc. In wine, part of the methional returns to methionol via catalyzed reduction by alcohol dehydrogenase with NADH. 

Certain bacterial strains prodnce bitterness in wine—a fact known since the time of Pasteur. Lactic acid bacteria make use of a glycerol dehydratase to transfonn glycerol into j0-hydroxy-propionaldehyde (Figure 5.8). This molecule is the precursor of acrolein, which is formed in wine by heating, or slowly during aging. The combination of wine tannins and acrolein, or its precursor, gives a bitter taste. 

In any species, some strains may induce wine spoilage. They can easily be detected by PCR using primers based on the sequence of genes responsible for the undesirable metabolism. This is the case of acrolein-, glucan-, and biogenic amine-producing strains (Claisse and Lonvaud-Funel 2001 Gindreau et al. 2001 Nannelli et al. 2008). 

Bauer, R., du Toit, M., and Kossman, J. (2010) Influence of environmental parameters on production of the acrolein precursor 3-hydroxypropionaldehyde by Lactobacillus reuteri DSMZ 20016 and its accumulation by wine lactoba-cilli. Int J Food Microbiol 137, 28-31. 

---