The degradation of anthocyanic pigments of fresh and industrial juices from
blood oranges were studied during storage periods of a few days at -18 deg
rees C and 12 months at 4 degrees C in nitrogen. The change of anthocyanin
pigments was followed by HPLC at 520 nm while the coloured polymeric pigmen
ts were fractionated by chromatography and characterized by their transform
ation indices and their reactivity with NaHSO3. The results show that the p
rocess of polymerization is accompanied by production of chemical indicator
s of sugar and ascorbic acid degradation (furfural and hydroxymethylfurfura
l). It seems that the resulting polymeric compounds have structures differe
nt from those of the compounds formed during wine processing. Reactions bet
ween 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.