Transformation of stacked π–π-stabilized malvidin-3-O-glucoside — Catechin complexes towards polymeric structures followed by anisotropy decay study

Unexpected effect of potassium ions on the copigmentation in red wines

“…However, in our previous works we have shown that the physicochemical background of the copigmentation processes affects significantly the color due to the change of the stability of the sandwich-type copigmentation complexes. Furthermore, in a recent paper (Kunsági-Máté et al, 2011) we showed that at an increased temperature two possible ways of dissociation of these complexes could happen: i) either the sandwich complexes dissociate then associate again into the same sandwich structure, or ii) they form polymer structure after the dissociation of the sandwich complexes. The former process is reversible while the latter process shows irreversible characters.…”

Anthocyanins and Their Variation in Red Wines I. Monomeric Anthocyanins and Their Color Expression

“…In red grapes and young red wines, anthocyanins exist primarily as weak complexes, either with themselves termed self-association, or with other compounds, termed co-factors, resulting in the formation of copigments [ 109 , 110 , 111 ]. These are considered to be formed by processes that involve stacked molecular aggregation, which is primarily held together by hydrophobic interaction [ 12 , 110 , 112 ]. They can significantly increase color density (hyperchromic effect), and may affect color tint, a bathochromic effect giving a more purple hue to young red wines by provoking displacement of anthocyanin equilibria towards their colored forms, which can explain many questions of color expression in young red wines [ 113 , 114 ].…”

The Effect of Temperature on the Color of Red Wines

“…Furthermore, the Portugieser showed much higher contents of noncolored phenols, which still might undergo browning, whereas in the case of the Bikatory wine browning in the same order of magnitude is not possible probably due to its slightly lower content on colorless polyphenols (refer Table 2). However, both the rate and the activation energy are similar to those associated with the transformation of stacked π–π‐stabilized malvidin‐3‐glucoside–catechin complexes toward polymeric structures (Kunsági‐Máté and others 2011). This property suggests that the optical changes obtained at 520 nm and 620 nm are presumably associated with the mentioned structural changes from stacked to polymeric forms.…”

“…The size and stability (Kunsági‐Máté and others 2006) of these complexes, as well as the effect of the change of the molecular environment (Kunsági‐Máté and others 2007; Kunsági‐Máté and others 2008a) during the fermentation processes, were studied. Recently, we have shown that the structure of anthocyanin–polyphenol changes from a stacked π–π‐interaction‐stabilized structure to a polymer structure with an increased rate at elevated temperature (Kunsági‐Máté and others 2011). However, it is obvious that the rate of the transformation highly depends on the activation energy associated with the transformation from the stacked to the polymeric form.…”