Analysis of polymeric pigments

Table 2.5 HPLC gradient program used for analysis of polymeric pigments in wine using a polystyrene divinylbenzene (100 A, 250 x 4.6mm, 5 pan) column (flow rate l.OmL/min) (Peng et al., 2002).

Analysis of polymeric pigments in parallel with tannin in wines or grape extracts required two 1.5 mL microfiige tubes for each sample. The first tube was made up by adding 1 mL of the acetic acid/NaCl buffer to the tube and then adding 500 pL of the diluted skin extract or wine. One mL of the mixture was transferred to a cuvette and the absorbance at 520 nm was determined (reading... 

The routine analysis of polymeric pigments in wine is based on the work of Somers who showed that monomeric anthocyanins are bleached with bisulfite whereas polymeric pigments are not (i,5). Thus, the difference in absorbance readings at 520nm before and after bleaching with bisulfite is widely used as a measure of the amount of polymeric pigment present in red wine. 

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