Abstract:

The effects of different temperature modes, including non-gradual cooling, gradual cooling, non-gradual
cooling combined with stepwise heating and gradual cooling combined with stepwise heating, on storage qualities
of Wujiuxiang pear, such as firmness, soluble solid content(SSC), titritable acidity, relative membrane permeability
and peel browning, were studied. All pears in this study were packaged in polyethylene film 0.010 mm thick. The
gradual cooling mode started from 10 ℃, reducing by 1 ℃ a day to 7 ℃, then by 2 ℃ a day to 3 ℃ and finally to
0 ℃ in one day. The non-gradual cooling mode was storage at 0 ℃ without gradual cooling. The sepwise heating
mode was exposure to 10 ℃ for 24 h followed by 25 ℃ for 24 h. Results showed that gradual cooling storage did not
significantly influence firmness, SSC or relative membrane permeability and favored the maintenance of titratable
acid content and inhibition of peel browning. Stepwise heating caused normal post-harvest ripening and softening of
pears which were manifested by a decrease in hardness and no significant variations in SSC, titratable acid content
or relative membrane permeability. During the first 150 d of storage peel browning became more serious and then no
significnat changes were observed. As a result, gradual cooling combined with stepwise heating may help preserve
Wujiuxiang pear by alleviating the reduction of hardness and peel browning.

Key words: Wujiuxiang pear, gradually reducing temperature, step heating, storage, peel browning