High-voltage electrostatic field combined with light-emitting diode irradiation: A new method for optimizing the quality of modified atmosphere packaged pakchoi

Pakchoi is one of the most popular leafy vegetables for fleet crews. Modified atmosphere packaging (MAP), most commonly used on ships today, can only extend the shelf life of pakchoi by up to 25 days, far short of the requirements for ocean voyages (>50 days). The objective of this study was to use a combination of emerging non-thermal physical fields (high voltage electrostatic field (HVEF), light emitting diode (LED) irradiation) and modified atmosphere packaging, acting on structural changes caused by external energy field and the molecular changes caused by signal molecular transfer, respectively, to produce a superimposed effect on the pakchoi thereby extending it shelf life to a predetermined target. The treatment maintained the chlorophyll content, ascorbic acid content, hardness and membrane system integrity of packaged pakchoi, effectively reducing respiration rate and polyphenol oxidase activity. Electronic nose and low-field NMR analyses also confirmed better flavor and less water migration in pakchoi. Hierarchical cluster analysis (HCA) revealed that pakchoi stored for 25 days could still be classified in the same category as fresh samples. The results showed that the shelf life of the shipboard pakchoi was successfully extended to 50 days, proving that the synergistic preservation treatment has promising applications.