Oligomeric anthocyanin formation in black table olives during anaerobic processing

The results of a study on the evolution of anthocyanins and colour during processing of black olives are reported. Olives of “Bosana” cultivars were collected at a technological black-ripe stage and were processed by the traditional anaerobic system. At regular intervals brines and olives were inspected for different parameters. The routine physico-chemical values in brines and olives changed as expected. The cyanidin-3-glucoside and cyanidin-3-rutinoside content were the main anthocyanins founded and showed a rapid decrease, presenting apparently a zero order kinetic, and later they completely disappeared. HPLC-MS revealed other peaks, corresponding to molecular ion at m/z 633, 711 (dimer) and oligomers. The first was detected throughout the processing time, while the bigger ones disappeared after the tenth day of sampling, if we except one, probably because the polimerisation process continued, thus enabling the formation of molecules that go beyond the instrument threshold. The colour stability of the olives is probably reasonably to be ascribed to the peak with molecular ion at m/z 633 and probably to the new forms.