The effect of hydrocooling on the keeping quality of early ripening pear cultivars.

The keeping quality of three early ripening pear (Pyrus communis) cultivars, two belonging to the local biodiversity ('San Domenico' and 'San Giovanni Migliorata') and a National one ('Coscia') was evaluated, during the postharvest life, as affected by two hydrocooling temperatures. Fruit of 'S. Domenico' and 'S. Giovanni Migliorata' were harvested in the middle of June and 'Coscia' in July, when they reached their optimal stage for consumption and before the internal breakdown started in the local cultivars. Harvest took place in the morning, and then in the laboratory all fruit was heat conditioned until the core reached 25°C. One third of the fruit was immediately cold-stored for 7 days at 5°C and 95±2% RH followed by a 3 day simulated marketing period (SMP) at 17°C and 75% RH. Half of the remaining fruit was hydrocooled with water at 0°C to reach 5°C inside the fruit (HC-5C) and the other half to reach 2°C (HC-2C). Then, fruit was cold-stored as reported above. Both hydrocooling temperatures improved the keeping quality of the pears, during storage and SMP. Compared to the control fruit, pulp of hydrocooled fruit remained more firm and in 'Coscia', handling blemishes were less evident. During the SMP most of the fruit of local cultivars that were not hydrocooled became un-marketable due to the internal breakdown and in 'Coscia' to the development of molds. With both hydrocooling temperatures the internal breakdown was completely inhibited during the whole experiment in 'S. Giovanni Migliorata', while in 'S. Domenico' the internal breakdown started during the SMP when fruit was hydrocooled up to 5°C. The results evidenced a strong effect of hydrocooling on the delay of internal breakdown in local early ripening pear cultivars.