Light emitting diodes for the improvement of postharvest quality of wild rocket in soilless and soil-bound cultivation systems

Wild rocket (<i>Diplotaxis tenuifolia</i> (L.) DC cv. Dallas) is a leafy green vegetable appreciated for its pungent taste and healthy properties, often consumed as a ready-to-eat product. The cultivation system is crucial in determining the overall quality, while postharvest storage is fundamental for preserving nutritional quality, phytochemicals, and vitamins. This study aimed to investigate the phytochemical content and microbiological quality of soilless (SS) and soil-bound (SB) wild rocket during cold postharvest storage under blue, red, and green Light Emitting Diode (LED). Blue LED increased chlorophylls and carotenoids in SB after two days of storage, and chlorophyll <i>a</i> in SS after seven days. Furthermore, it reduced H₂O₂ levels after two days (SS and SB) and lipid peroxidation in SB. Red LED increased phenols in both SS and SB but was detrimental to chlorophyll, carotenoids, and oxidative markers. Green LED had less significant effects. Microbiological growth varied with LED treatment: green light increased mesophilic bacteria in SB, and red light did so in SS by day four, while blue light reduced bacterial growth at the end of storage. Overall, Blue LED was the most effective LED in preserving postharvest quality. Soilless cultivation was particularly beneficial in reducing lipid peroxidation and maintaining cell membrane integrity during long-term storage, and it might also be more effective in preserving ascorbic acid. Conversely, soil-bound cultivation methods could enhance initial polyphenol content or better preserve it during early storage. This study highlights the complex interplay of pre-harvest conditions, postharvest quality, and shelf-life performance.