Relationship between watercore and maturity or sorbitol in apples affected by preharvest fruit temperature

Abstract

The effect of preharvest fruit temperature on the relationships between development of watercore and ethylene evolution, flesh firmness, membrane permeability and sorbitol level in two watercore-susceptible apple ( Malus domestica Borkh.) cultivars, `Himekami' and `Fuji', was investigated at ambient or modified temperatures of 10, 15 or 25°C. Watercore occurrence was completely inhibited at 25°C in both cultivars whereas fruit subjected to 10 or 15°C exhibited significantly higher watercore ratings after two or three weeks of the treatment than those at 25°C and ambient temperatures. Ethylene production of `Himekami' apples increased at 25°C and ambient temperature but not at 15°C. Ethylene production was not affected by treatment in `Fuji' apples. Flesh firmness of `Himekami' tended to maintain a higher level at 15°C than at 25°C, while there was no clear difference among the treatments in `Fuji'. The rate of potassium (K) ion elution from the flesh tissues of either cultivar was not affected by fruit temperature treatment. Sorbitol content at 15°C maintained significantly higher level than that at 25°C during the treatment in `Himekami' apples although no sorbitol difference was observed among the temperature treatments in `Fuji' apples.