Postharvest pitting in Navel oranges at non-chilling temperature: influence of relative humidity.
Alferez, F. and Zacarias, L.
ISHS Acta Horticulturae 553: 307-308.
2001
บทคัดย่อ
The effect of relative humidity (RH) and its variation during storage of Navel oranges on the development of rind staining and the potential relation with changes in respiration rate, ethylene production and internal gas concentrations were investigated. Navelate and Navelina oranges were harvested at commercial maturity and stored at 20 deg C and 45% or 95% RH. Fruits stored at high RH were maintained in plastic boxes with a continuous flow of humidified air. Wax treatments with commercially available polyethylene-based wax (17% solids) were applied to Navelina oranges. At intervals, fruit weight was determined, and after a weight loss of around 2% and 4.5% was achieved, the fruits were transferred from 45% to 95% RH. During storage of Navelate oranges at 20 deg C and at either 45% or 95% RH, peel pitting was very low and the rate of weight loss was about 4 times higher at 45% than at 95% RH. Transfer of the fruit to 95% RH after 1 or 2 weeks at 45% rapidly reduced weight loss and increased peel pitting. Initial symptoms of peel depression became apparent a few days after the transfer and spread progressively over the fruit surface, forming brown and dark clusters. Transfer of the fruit from 45% to 95% RH almost doubled the respiration rate and increased ethylene production 7 times, irrespective of the time of transfer, reaching their maximum 24 h after the change in RH. In waxed Navelina fruits transferred to 95% after 7 days at 45% RH, the rind staining index was slightly lower (1.1) than in the non-waxed fruits (1.7), but, as expected, internal CO2 and ethylene concentrations were much higher (4.3% and 3.9 ppm, respectively) than in the non-coated fruits (1.6% and 0.7 ppm, respectively).