Cell wall-modifying enzymes and firmness loss in ripening 'Golden Reinders1 apples: A comparison between calcium dips and ULO storage

摘要

Calcium treatment and storage under ultra-low oxygen (ULO) conditions are common post-harvest practices aimed at delaying ripening-related softening of apple (Malus x domestica Borkh.) fruit, but the biochemical mechanisms underlying these effects have not been determined conclusively to date. In this study, commercially mature 'Golden Reinders' apples were dipped in 2% calcium chloride prior to storage at 1 ℃ and 92% RH under either regular air or ultra-low oxygen (ULO; lkPa O_2:2kPa CO_2) for 19 or 31 weeks, and kept thereafter at 20 ℃ for 0, 7 or 14 days in order to simulate the usual marketing time. Cell wall composition and cell wall-modifying enzyme activities were determined in relation to fruit firmness. ULO-storage and calcium dips were effective for firmness preservation, seemingly due to decreased pectin solubilisation. (3-Galactosidase, α-L-arabinofuranosidase and pectate lyase activities were correlated positively with firmness loss of 'Golden Reinders' fruit after storage.