Wine Chemistry and Biochemistry

(Steven Felgate) #1

9A Anthocyanins and Anthocyanin-Derived Compounds 451


acid/malvidin-3-glucoside since the concentration of caffeic acid remained very


stable during the storage time. However, a minimum concentration of malvidin-


3-glucoside (5–10 mg/L) was found to beneeded to maintainthe reaction rate


high enough to compensate for its simultaneous incorporation into other prod-


ucts. Recently, Rentzsch et al. (2007) also confirmed that Pinotin A formation


in Grenache red wines only takes place after a prolonged aging time, whereas


hydroxyphenyl-pyranoanthocyanins derived fromp-coumaric and ferulic acids were


produced by the enzymatic pathway during fermentation and by chemical synthesis


during the aging process.


9A.2.4.2 Anthocyanin-Vinylflavanol Condensation Reactions:


Flavanyl-Pyranoanthocyanins


Precursors.The precursors for this reaction are anthocyanins, flavanols or flavanols


containing a vinyl residue at C-8 (i.e., 8-vinylflavanols). 8-Vinylflavanols could arise


from the cleavage of flavanol-ethyl-flavanol oligomers or from the dehydration of


the flavanol-ethanol adduct formed after the attack of aldehyde cation to the flavanol


(Chapter 9B). Saucier et al. (1997) have supported evidence for this precursor when


detecting an ion corresponding to vinyl-catechin from the fragmentation of ethyl-


linked catechin dimers under ESI-MS in positive or negative mode.


Mechanism of reaction.The mechanism proposed for the formation of flavanyl-


pyranoanthocyanins (Francia-Aricha et al. 1997; Mateus et al. 2003a,b) (Fig. 9A.3g),


is similar to that described above by Fulcrand et al. (1996) for the formation of


hydroxyphenyl-pyranoanthocyanins (Sect. 9A.2.4.1; Fig. 9A.3f).


Evidence in wine.Flavanyl-pyranoanthocyanins derived from the reaction bet-
ween malvidin-3-glucosideand (+)-catechin, (–)-epicatechin and procyanidin B2,


first reported in model solutions containing malvidin-3-glucoside, acetaldehyde and


the respective flavan-3-ol (Francia-Aricha et al. 1997), have also been identified in


wines (Mateus et al. 2003a,b; Atanasova et al. 2002a; Alcalde-Eon et al. 2004, 2006;


Mateus et al. 2003a; Monagas et al. 2003; Wang et al. 2003a; Boido et al. 2006).


Complete NMR characterization has been provided for the flavanyl-pyrano


derivatives of malvidin-3-glucoside and itsp-coumaroyl ester with (+)-catechin, (–)-


epicatechin and procyanidin B3 and for derivatives of malvidin-3-(6-p-coumaroyl)-


glucoside with (+)-catechin, (–)-epicatechin and procyanidin B1 isolated from Port


wines (Mateus et al. 2002b, 2003a). Asenstorfer et al. (2001) have identified a large


family of flavanyl pyranoanthocyanins of oligomeric nature including the –di-, tri-


and tetra-catechin-pyrano derivatives of malvidin-3-glucoside and its acylated forms


in a commercial grape marc. Atanasova et al. (2002a) also demonstrated, via thiol-


ysis, that both monomeric flavanols and proanthocyanidins could be involved in the


formation of anthocyanin-vinylflavanol adducts.


He et al. (2006a) isolated and quantified oligomeric flavanyl-pyranomalvidin-


3-glucosides [(+)-catechin, (–)-epicatechin and procyanidin B3] and flavanyl-


pyrano-malvidin-3-(6-p-coumaroyl)-glucosides [(+)-catechin, (–)-epicatechin and


procyanidin B1] from Port wine from different ages (3-, 4- and 6-year-old wines). In


general, the profile of flavanyl-pyranoanthocyanin pigments in the different wines

Free download pdf