Yeast metabolites involved in anthocyanin transformations

The most well known of them are probably the carboxypyranoanthocyanins that result from the reaction of anthocyanins with pyruvic acid (in its enolic form). The formation of carboxypyranomvSglc in red table wine is thought to occur during fermentation (Fulcrand et al, 1998) when the highest pyruvic acid concentration exists. 

Vitisin B pigments are another minor group of pyranoanthocyanins that show no substituent on the pyranic D-ring (Bakker Timberlake, 1997). These pigments were described to result from the direct reaction between anthocyanins and acetaldehyde. However, there is no consensus on this matter because that reaction is very difficult to occur in model wine conditions and the mechanism involved is not fully understood. Morata et al. (2007) have observed that the addition of acetaldehyde (200 mg L ) to a young red wine (cv. Tempranillo) led to the production of fivefold amounts of vitisin B after 4 weeks with control wines (Morata et al, 2007). 

R3=COOH, R4=H pyruvic acid R3sR4sH, acetaldehyde R3sCH3, R4sCOOH acetoacetic acid R3sCH3, R4=H acetona 

R3sCOOH carbojQ pyranoanthocyanin R3sH pyranoanthocyanin R3SCH3 raethylpyranoanthocyanin 

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