Boiling was the most efficient pretreatment method for the extraction. The resulting anthocyanin-rich extract contained glucose , proteins , amino acids , and unidentified compounds as impurities.
Removal of these by adsorption was studied with six commercially available adsorbents , of which Amberlite XAD-7HP was the mostefficient.
Anthocyanin purification with XAD-7HP was studied in a column.
Desorption of anthocyaninscould be done efficiently with 75 vol.% acidic (7 vol.% acetic acid) aqueous ethanol.
All glu-cose and unknown impurities , together with 87% of proteins and amino acids , could beseparated from the anthocyanins.