The Role of Protein Contents and Enzyme Activity on Creasing of Washington Navel Orange Fruits

Creasing is one of the main physiological disorders of navel orange fruit representing a high reduction percentage of fresh fruit. Creasing incidence, its possible relationship with the role of protein and enzyme activities were approached. A research study was conducted for two consecutive seasons to monitor and evaluate the protein and enzyme activities in creased and non-creased fruits of Washington navel orange in Delta, Egypt. Further parameters such as fruit physical and chemical characteristics were measured as well as the percentage of creased fruits as affected in three dates i.e. mid Jan., first of Feb. and first of March and two tree geographical directions, i.e. north and south. The obtained data revealed that creasing percentage was increased progressively with fruit aging, and creasing incidence was relatively influenced by geographical direction (more pronounced in fruits of northern tree periphery). Meanwhile, the protein banding patterns of albedo and flavedo total proteins exhibit the association between some particular protein types and the changing in citrus peel tissue from healthy to crease. Moreover, the higher amount of PG-ase release was tended to be closely related to albedo taken of creased fruits compared to non creased ones.