Ripening behavior and combined fungicide and prestorage heat effects on decay control of `Bosc' pears in air or step-wise low oxygen storage
Paul M. Chen, Robert A. Spotts, Diane M. Varga and Louis A. Cervantes
Postharvest Biology and Technology Vol: 6 Issue: 3-4 Pages: 235-248.
1995
บทคัดย่อ
`Bosc' pears (Pyrus communis, L.) harvested at commercial maturity with flesh firmness (FF) of 75 Newton (N) from the southern district of Oregon were stored in either air or step-wise low O2 at -1°C during the 1992-'93 and 1993-'94 seasons. The levels of O2 in the step-wise low O2 storage were maintained and increased from 0.5% for four months to 1.0% for two months, and finally to 1.5% for two months while the CO2 concentration in the storage was kept below 0.05%. Air-stored fruit were capable of ripening normally with good dessert quality after one, two, and three months of storage. These fruit softened to between 9.7 N and 15.0 N and reached the ethylene climacteric peak on day 7 or 8 of ripening at 20°C. The ripened fruit developed a buttery and juicy texture as indicated by an apparent reduction of extractable juice (EJ) from 67 ml juice per 100 g fresh weight (FW) of unripened pulp tissue to less than 45.0 ml juice per 100 g FW of ripened pulp tissue. Fruit in air storage for four and five months reached the ethylene climacteric peak on day 4 of ripening but did not soften properly. Fruit stored in step-wise low O2 for six, seven and eight months reached the ethylene climacteric peak on day 6 of ripening. Step-wise low-O2-stored fruit softened properly to 12 N or lower and reduced EJ to 49 ml 100 g-1 FW (six and seven months of storage) or 59 ml 100 g-1 FW (eight months of storage) on day 8 of ripening. Based on the analyses of ethylene production, furit softening and reduction of EJ during ripening, fruit stored in the step-wise low O2 storage for six, seven and eight months maintained a physiological state similar to the fruit stored in air for one to three months. The combination of prestorage heat (28°C for one day) and step-wise low oxygen storage effectively reduced side rot by 60 and 63% in 1993 and 1994, respectively. Even greater decay control was obtained with the fungicides imazalil and Exp10412A on inoculated fruit, and thiabendazole plus captan on non-inoculated fruit.