Effects of blue light combined with melatonin on antioxidant activity and nutritional value of postharvest Chinese cabbage (Brassica rapa L. ssp. pekinensis)

Chinese cabbage is an economically important vegetable crop and is widely cultivated and consumed as a staple food. This study evaluated the synergistic effects of postharvest blue light illumination and melatonin treatment on glucosinolate profiles, antioxidant metabolism, and storage quality of Chinese cabbage. The combined blue light and melatonin treatment significantly enhanced antioxidant activity in Chinese cabbage, with 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and ferric-reducing antioxidant power increased by 50.25% and 16.64% at 8 days of storage, respectively. Additionally, it promoted the accumulation of key enzymes, including catalase, peroxidase, and superoxide dismutase, as well as non-enzymatic antioxidants such as total phenols and total flavonoids. Due to the regulation of these metabolic pathways and the enhanced expression of biosynthetic genes, the combined treatment significantly promoted the accumulation of indole-3-ylmethyl, 1-methoxyindole-3-ylmethyl glucosinolate, and total glucosinolates. These findings suggest that the combined blue light and melatonin treatment represents a promising approach for enhancing the nutritional value, antioxidant properties, and maintaining commercial quality of Chinese cabbage during storage.