Evaluation of a 405 nm LED illumination-complemented refrigeration system for leafy greens preservation: Phytopathogens inactivation, quality, and metabolite regulation

초록

A 405 nm LED illumination-complemented refrigeration system (LCRS) was evaluated for the inactivation of Pseudomonas marginalis, Pantoea ananatis, and Alternaria brassicicola, and the preservation of the nutritional quality of leafy greens. A minimum irradiance of 2.0 mW/cm2 was required to achieve an in vitro antibacterial effect over a 270-min exposure. In comparison, a near-complete in vitro antifungal effect was achieved at 18.5 mW/cm2 within a 540-min exposure. A maximum reduction of 97% and 71% was observed, respectively, for bacteria and fungi, when the pathogens were inoculated on single leaves of kai lan and iceberg lettuce shreds. The LCRS did not produce any significant difference in water activity, pigmentation, antioxidant capacity, and metabolite profile, but caused increases in mass loss and perceptible colour change, and a decrease in firmness. The results suggest the promising potential of the LCRS for phytopathogens inactivation and regulating the metabolite profile of leafy greens towards their overall preservation.

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