Influence of Combined Edible Coating with Chitosan and Tea Polyphenol on the Quality Deterioration and Health-promoting Compounds in Harvested Broccoli

Rapid quality deterioration after harvest restricts the shelf life of broccoli, and reduces its commercial value. In this study, the effects of combined edible coating with chitosan and tea polyphenol (CTS + TP) on the post-harvest quality of broccoli were investigated. Results showed that the combined treatment of chitosan and tea polyphenol had better effects on the decay rate, weight loss rate, and respiratory intensity of broccoli than the single chitosan treatment and control. CTS + TP treatment mitigated the severity of broccoli yellowing, which was demonstrated by the higher hue angle, chlorophyll level, and strong red fluorescence emission of the treated samples, as well as delayed yellowing time compared to that observed in controls. Moreover, CTS + TP treatment better protected the sensory quality of the product, such as odor, hardness, and chewiness, and prevented evident changes. The vitamin C level in the treated samples was extremely higher, and the higher antioxidant capacity was also noted. The content of sulforaphane, the typical bioactive substance of broccoli, declined conspicuously in the yellowed broccoli, while the change was noticeably relieved by CTS + TP coating. The significantly upregulated expressions of BoCYP83A1, BoMYB28, and BoMYR in treated samples may have played an important role in the improvement of sulforaphane contents. These findings indicated that the edible coating with CTS + TP alleviated yellowing symptoms, improved the sensory quality, and enhanced the nutraceutical value of broccoli.