Degradation of anthocyanins from blood orange juices

The degradation of anthocyanic pigments of fresh and industrial juices from blood oranges were studied during storage periods of a few days at −18 °C and 12 months at 4 °C in nitrogen. The change of anthocyanin pigments was followed by HPLC at 520 nm while the coloured polymeric pigments were fractionated by chromatography and characterized by their transformation indices and their reactivity with NaHSO3. The results show that the process of polymerization is accompanied by production of chemical indicators of sugar and ascorbic acid degradation (furfural and hydroxymethylfurfural). It seems that the resulting polymeric compounds have structures different from those of the compounds formed during wine processing. Reactions between anthocyanic pigments and the intermediates of degradation of sugar and ascorbic acid in an acidic environment are the main causes of formation of these polymers.