Figure 2 shows the changes in PPO activity in
the samples as influenced by the chemical
treatments during dark storage at 4oC. The
activity continued to increase throughout the
storage period regardless of the treatments.
The rapid increase in the activity might be due
to increased respiration rates following peeling
and cutting. The activity of apple cubes showed
a significant increase between 0 day and 3 days.
This contrasts with the color data (Hunter L
value) which showed a large decrease between
0 day and 3 days. The PPO activity of fresh-cut
apple cubes was most effectively inhibited by
0.5% cysteine during storage at 4oC for 7 days.
Apple polyphenoloxidase was at least twice as
active with chlorogenic acid compared to
catechins. Both classes of phenols are
important for browning (