UBC Theses and Dissertations
Modification of the incidence of surface damage symptoms in sweet cherries by pre- and postharvest treatments Lidster, Perry David
The prevention of storage disorders in sweet cherries resulting from mechanical damage was investigated. Pre- and post-harvest treatments were applied to modify fruit texture, fruit composition and fruit desiccation in storage. The effects of the treatments applied were related to fruit susceptibility to the incidence of fruit bruises, surface markings and surface pitting. The application of calcium in the form of pre-harvest sprays or post-harvest dips decreased mechanical damage expression. Warm fruit was less susceptible to mechanical injury than cold fruit early in the storage period but fruit temperature had little effect after 8 days of cold storage. Similarly, high storage temperatures enhanced pitting development early in the storage life but storage temperatures had negligible effect after 8 days. A delay in 0℃ storage prior to bruising greatly reduced the susceptibility of cherries to mechanical injury. Fruit was most resistant to mechanical damage after 8 days in 0°C. The development of fruit symptoms in response to impact was enhanced by rough surfaces. Slowly applied compressive forces resulted in low incidences of injury symptoms. Fruit firmness and bioyield values were increased with mesocarp calcium from preharvest sprays and post-harvest dips, but did not show consistent relationships to the susceptibility of fruit to mechanical damage. Weight loss enhanced by low relative humidity increased the rate of development of damage but did not influence the total damage incidence. Soaking fruit in water or fungicide solution increased damage expression in storage. Less mature and intermediate maturity fruit were more susceptible to mechanical injury than were the most mature fruit. Fruit with relatively high alcohol insoluble solids content associated with pre-harvest gibberellic acid sprays or advanced maturity fruit had reduced susceptibility to mechanical damage. Large fruit was less susceptible to mechanical damage and had higher alcohol insoluble solids content than did small fruit. High levels of fruit nitrogen were associated with high susceptibility to mechanical damage. A great many factors were found to modify fruit susceptibility to surface disorders resulting from mechanical damage. This provides a great flexibility to producers and marketing agents to minimize fruit losses due to the effects of rough handling.
Item Citations and Data