Involvement of POD in enzymatic browning of fruit and vegetables
has been widely reported (Nicolas et al., 1994; Williams
et al., 1985). POD enzyme oxidizes phenolics to quinones, which
are condensed to form browning polymers in the presence of H2O2
(Robinson, 1991). Those reactions caused undesirable changes in
the products affecting their quality. Zhou et al. (2003) verified that
POD activity is present in pineapple fruit during the whole postharvest
period. However, no significant changes in POD activity
were found during storage at different temperatures in the experiment.
Our result is consistent with the earlier report of Graham et al.
(1998) and Zhou et al. (2003) that POD activity remained unaltered
during the induction of internal browning of pineapple fruit. This
is an indication that POD may be not a key enzyme in the internal
browning process.