CONTROLLED ATMOSPHERE STORAGE OF 'SPADONA' PEARS

Pear fruit are often stored in controlled atmosphere (CA) for up to 12 months in Israel. A number of new agro-technical procedures have become routine in pear orchards, including the use of the synthetic cytokinin CPPU two weeks after full bloom to increase fruit size. This change in management conditions led us to validate the efficacy of the accepted CA formula of 1.5% O₂ and 2% CO₂. ‘Spadona’ pears were harvested three times in July from three orchards in the north of Israel. The fruit were first treated against decay (Marpan) and superficial scald (Ethoxyquin), sorted, samples were taken for ripeness parameters, and the rest placed in storage. The fruit were placed in storage at -1°C and CA of 1.5% O₂, with CO₂ concentrations of 0.5, 2, 5 and 7%, with an air storage comparison. Two removals were conducted, after 5 and 10 months, and evaluation was performed at removal and after 5 days at 20°C.
After 5 months of storage the fruit were of good appearance, except for some decay in the air and 0.5% CO₂ stored fruit. There was also CO₂ internal damage in one orchard at 7% CO₂. Scratches appeared during shelf life, with the least in 5 and 7% CO₂. After 10 months, fruits from air storage had high levels of decay. There was decreasing firmness in the fruit as the harvest was later, and as CO₂ conditions were lower. CO₂ damage was apparent at 5% although only in the third harvest, and in 7% in all harvests. Internal browning was greatest in air and 7% CO₂ stored fruit, and almost absent in 2% CO₂ stored fruit. Taste tests were conducted in shelf life after both removals and overall taste was found to be best in fruit from 2% CO₂ and two orchards registered good taste in 5% CO₂. In conclusion, an atmosphere of 2% CO₂ and 1.5% O₂ is still the best for storage of ‘Spadona’ pears, although early harvested fruit benefit from 5% CO₂. Storage in 5% CO₂ led to firmer fruit and less scratch development during shelf life than 2% CO₂, but there was a danger of internal damage in later harvests.