Selective binding of potassium and calcium ions to novel cyclic proanthocyanidins in wine by high‐performance liquid chromatography/high‐resolution mass spectrometry

Abstract

Wines from 19 grape varieties were investigated in order to identify potassium and calcium complexes of non- and cyclic B-type proanthocyanidins that were recently discovered. The results showed a dependence of the distribution of metal complexes according to the cyclic or non cyclic geometry of proanthocyanidins. The multivariate analysis of the mass spectrometric results showed a relationship with the grape variety, however not so straightforward as evidenced for the non-complexed species.

Relative abundances of novel cyclic prodelphinidins in wine depending on the grape variety

“…As seen earlier for PAC without (epi)gallocatechins, a dependence is present over the grape variety as shown with ANOVA (Table SI 1, Supporting Information). At the same time, the PCA run on these observations, using only these four variables, explained 100% of the variance (see PC1 vs PC2 and PC1 vs PC3 in Figure SI 25 and Figure SI 26 in Supporting Information).…”

“…The amount of PAC in red wines was one order of magnitude higher than in white wines. However, as it was seen previously for PAC without (epi)gallocatechins, the calculated ratios carry much more information. Red and white wines showed increasing proportions of the cyclic analogs (from 4 to 6 units) towards heavier PAC (while the overall PAC abundance decreased).…”

“…The HPLC‐HRMS/MS method applied was adapted from published reports . The HPLC‐HRMS system used consisted of a Q Exactive HRMS instrument (Thermo Fisher Scientific, Waltham, MA, USA) coupled to an Agilent 1260 HPLC (Agilent Technologies Santa Clara, CA, USA) with a 16 channel DAD detector.…”

“…The HPLC-HRMS/MS method applied was adapted from published reports. [11][12][13][14][15] The HPLC-HRMS system used consisted of a Q Exactive…”

“…In fact, besides (+)‐catechin and (−)‐epicatechin, many more possible monomer units with different substitutions should be considered for building up the wide proanthocyanidins class, as for example (epi)gallocatechin, (epi)catechin gallate, (epi)afzelechin and O ‐mono‐ or di‐methylated (epi)gallocatechins (the latter ones are not actually present in grape) like observed with linear proanthocyanidins in wine, grapes, and other plant sources (Figure ) . Besides, potassium and calcium complexes of non cyclic and cyclic B‐type proanthocyanidins were recently discussed in relation with their relative isomeric abundances in wines …”