A novel strategy of using ultraviolet a light emitting diodes (UVA-LED) irradiation extends the shelf-life and enhances the antioxidant property of minimally processed pakchoi ( subsp. ).

Ultraviolet A light-emitting diode (UVA-LED) is an emerging non-chemical technology with potential of enhancing postharvest quality of fresh produce. This study compared effects of UVA-LED irradiation (0-control, 4, 8, 12, 16, 20 J/cm) on senescence and shelf-life of minimally processed pakchoi (MPP). An 8 J/cm dose effectively preserved chlorophyll and color, extending 2 days shelf-life. Further analysis revealed that UVA-LED (8 J/cm) increased phenolic acids (+ 18.21 %) and flavonoids (+ 57.50 %) at d5 by activating enzymes (phenylalanine ammonia-lyase-(PAL), cinnamate-4-hydroxylase-(C4H), and 4-coumarate: coenzyme A ligase-(4CL)), and upregulating corresponding genes. Moreover, UVA-LED enhanced 30 % - 40 % total antioxidant capacity (TAC) at d5, associated with elevated levels of both enzymatic (superoxide dismutase (SOD, +22.75 %), catalase (CAT, +68.00 %), and peroxidase (POD, +45.81 %), and non-enzymatic (total phenolics (1.21-fold), total ascorbic acid (1.90-fold)) antioxidants. However, UVA-LED accelerates fresh weight loss. Conclusively, proper dose UVA-LED irradiation presents an innovative strategy to preserve vegetables postharvest quality.