Decay Incidence and Quality Changes of Film Packaged 'Simeto' Mandarins Treated with Sodium Bicarbonate

Abstract: Not rinsing sodium bicarbonate (SBC) treated fruit with freshwater can reduce post-harvest decay, but it can also be phytotoxic to peel tissues. Film packaging delays the ageing of peel, due to the high in-package humidity, but this also stimulates the growth of pathogens. Thus, as stand-alone treatments, both SBC and film packaging present advantages, but also drawbacks. In this study, SBC phytotoxicity was effectively mitigated when 'Simeto' mandarins, subjected to a 2 min dip treatment in a 2% SBC solution, were packaged using Omni film (highly permeable to water vapor and gases) or Coralife SWAF 400 film (with a low permeability to water vapor, but moderately permeable to gases). In particular, the combination Coralife SWAF 400 film allowed the fruit to be stored for 7 d at 5 °C, or 14 d at 20 °C, with negligible changes in overall appearance, almost no loss caused by decay, and an average weight loss of 1.3%. The in-package air composition, similar to air in Omni packages, and with an average between 5 kPa CO2 and 16 kPa O2 in Coralife SWAF 400 packages, slightly affected the sensory and chemical qualities. Combining SBC with film packaging is a feasible method to prolong the post-harvest life of citrus fruit, and control post-harvest diseases, while avoiding the use of synthetic fungicides.