Although PPO has poor affinity for these pigments its action is
strongly enhanced by the presence of phenols. The
latter induces high rates of o-quinone synthesis and
acts as activators of anthocyanin degradation . POD may also be
involved in the degradation of anthocyanins . Its activity may be limited by the
availability of H2O2in situ. Browning may also result
from the direct action of anthocyanase on anthocyanins.
Anthocyanidins thus formed are spontaneously dam-aged at high pH (above 4.7 in vivo) ,
and their degradation products are potential substrates
for PPO (Zhang et al., 2001).