454 M. Monagas and B. Bartolom ́e
(Asenstorfer et al. 2003). Similarly, malolactic fermentation can also affect the pro-
duction of the pigment since lactic acid bacteria have the capacity of using pyruvic
acid (Asenstorfer et al. 2003). No synthesis and/or losses of the pigment were found
at low SO 2 concentration and occurrence of malolactic fermentation, while a maxi-
mum production was achieved under the opposite conditions.
The evolution of anthocyanin-pyruvic acid adducts during wine aging seems
to follow different patterns in function of the fermentation and aging conditions
employed during the winemaking process. For instance, in wines treated with pec-
tolitic enzymes, Revilla and Gonz ́alez-San Jos ́e (2001) found an increase in the
concentration of malvidin-3-glucoside pyruvate during the first six months of aging
in bottle, followed by a slight decrease.Similarly, Atanasova et al. (2002a) found
an increase in these pigments both in non-oxygenated and oxygenated wines during
a seven-month period, concluding that the anthocyanin-pyruvic acid condensation
reaction was not influenced by oxygen. On the other hand, Mateus et al. (2001)
reported losses (9–18%) of malvidin-derived pyruvic acid adducts in Port wines
during 38 months in bottles, although losses were higher (70%) in wines stored in
oak barrels (oxidative conditions) during the same period of aging. Finally, P ́erez-
Magari ̃no and Gonz ́alez-San Jos ́e (2004) reported an increment of these derivatives
in red wines during the first eight months of storage in oak barrels.
9A.2.4.4 Pyranoanthocyanins as Precursors of Other Anthocyanin-Derived
Pigments: Vinylpyranoanthocyanin Pigments
Precursors. Carboxy-pyranoanthocyanins (Sect. 9A.2.4.3), 8-vinylflavanols and
vinylphenols are the precursors for this reaction. The origin of 8-vinylflavanols and
vinylphenols in wine has been already described in Sects. 9A.2.4.2 and 9A.2.4.1,
respectively.
Mechanism of reaction.Flavanyl-vinylpyranoanthocyanin pigments, also called
“portisins”, were first isolated from aged Port wine (Mateus et al. 2003b). Their
characterization by ESI/MS and NMR revealed a structure comprised of a pyranoan-
thocyanin linked to a flavanol by a vinyl bridge (Mateus et al. 2004) (Fig. 9A.3j).
The proposed mechanism suggests that carboxy-pyranoanthocyanins, derived from
the condensation reaction between anthocyanins and pyruvic acid, react at its C-
10 position with the vinyl group of an 8-vinylflavanol derivative. The last step of
the synthesis involves the loss of the formic group followed by oxidation giving
rise to a pigment of blue color. This mechanism could be also extrapolated to
the formation of phenyl-vinylpyranoanthocyanin pigments formed from the reac-
tion between carboxy-pyranoanthocyanins and vinylphenols (Mateus et al. 2006;
Oliveira et al. 2007) (Fig. 9A.3k).
Evidence in wine.The procyanidin dimer-vinylpyranomalvidin-3-glucoside and
itsp-coumaroyl ester have been isolatedfrom Port wine and completely charac-
terized by ESI/MS and NMR (Mateus et al. 2003b). Later, the catechin-vinylpyrano
derivatives of petunidin, peonidin and malvidin-3-glucosides, malvidin-3-(6-acetyl)-
glucoside and peonidin and malvidin-3-(6-p-coumaroyl)-glucosides, have also been