Relationship between enzymatic browning and internal disorders in controlled-atmosphere stored pears

The relationship of browning potential and polyphenoloxidase activity (PPO, EC 1.14.18.1) to the internal disorders brown heart (BH) and core breakdown (CB) was studied in pears stored in controlled atmosphere (CA) and ultra low oxygen atmosphere (ULO). Brown discoloration of the core and flesh areas depended on harvest date—the earlier the picking date, the higher the browning. In contrast to browning potential, which declined steadily during storage, PPO activity in flesh increased. No difference was found between the two storage atmospheres (CA and ULO). ULO-stored fruits showed the higher incidence in internal disorders. PPO activity was clearly inhibited in BH-damaged fruits but transiently increased in CB-damaged fruits. These results indicated that enzymatic browning and PPO enzyme are not directly correlated with the BH and CB disorders and not directly involved in their formation. © 1998 Society of Chemical Industry