Fresh Florida citrus is well known for its excellent taste and juiciness. However, peel disorders sporadically develop after harvest that make the fruit unmarketable, or even worse, show up upon arrival at destination markets. These can be difficult to mitigate because a wide range of peel disorders can produce similar symptoms, and we often do not fully understand the underlying cause(s). Resulting economic losses can run into the millions of dollars and reduce buyer confidence for future purchases. Some types of peel breakdown, such as oil spotting (oleocellosis), chilling injury (CI), and one type of postharvest pitting (PP) are easier to mitigate because they are more clearly related to specific harvest or postharvest handling practices. For example, PP has been related to low internal oxygen concentrations within warm (>50°F) fruit coated with waxes that restrict gas diffusion (e.g., some shellac-based waxes). Improved cooling practices and the use of coatings with better gas diffusion have reduced the occurrence of PP. CI is caused by holding fruit at low, but non-freezing temperatures during storage and transit. However, modern handling practices have made CI a rare occurrence on Florida citrus.
Other types of peel disorders, such as stem-end rind breakdown (SERB) and general peel pitting are influenced by both pre- and postharvest factors and their occurrence can vary considerably from one season to the next. While the cause(s) of these disorders are not completely understood, they appear to be most related to the water status of the fruit. They may first appear during the winter months, especially after cool and/or windy weather with low relative humidity (RH), and continue into the spring at the end of the dry season and as field temperatures increase. Tree water stress from the lack of rain or insufficient irrigation before harvest can significantly increase peel breakdown after harvest. Conversely, application of an antitranspirant (e.g., 1% or 2% Vapor Gard) to the trees decreases the permeability of the fruit cuticle to water loss and reduces postharvest peel breakdown.
Time And Care