Anthocyanins polymeric color analysis

Polymeric color is a term that has been recognized in the wine industries for many years. Condensation of anthocyanins and proanthocyanidins may contribute to the formation of polymeric color, although the structural characterization of the compounds that contribute to polymeric color are poorly defined. Studies using electrospray mass spectrometric analysis demonstrated the presence of pigmented material from grape skins that was chiefiy composed of direct condensation products of anthocyanins extending up to trimers (Vidal et al., 2004). Recent studies have evaluated the effects of processing of blueberries. 

It is critical to recognize the high reactivity and low stability of anthocyanins in the selection of methods of extraction and quantitation in the analysis of anthocyanins. An analysis of processed samples containing anthocyanins for polymeric color as well as monomeric anthocyanins is recommended in nutrition studies until we better understand any health effects (positive or negative) of the compounds that are part of the mix measured as polymeric color. ... 

As red wines age, the monomeric forms of anthocyanins undergo condensation reactions with other anthocyanin or tannin molecules to form polymeric pigments. The polymeric pigments are less sensitive to bisulfite bleaching and changes in pH (10). The color analysis method of Somers and Evans (10) as described above takes advantage of these differences to follow color changes as wines age. 

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