Changes in sterol and phospholipid composition of apples during storage at low temperature and low oxygen concentration

Free sterol and phospholipid in the cortical tissue of apple were determined during storage of the fruits in air at 12 and 3.5°C and in 2 kPa O2 (98 kPa N2) at 3.5°C. In air at 12°C, the sitosterol content declined slightly (about 4%) during fruit ripening whilst phospholipid increased about 8%. At 3.5°C in air and 2 kPa O2, sitosterol content increased by 16% and phospholipid by 25–31%. The increase in phospholipid in 2 kPa O2 occurred more slowly than in air. Transfer of apples to air after 33 or 64 days in 2 kPa O2 led to rapid accumulation of phospholipid in the fruit (20% and 10%, respectively) compared with apples maintained in 2 kPa O2. An increase in concentration of phosphatidylcholine (PC) accounted for most of the change observed in total phospholipid.