Carboxymethyl cellulose-based water barrier coating regulated postharvest quality and ROS metabolism of pakchoi (Brassica chinensis L.)

The postharvest preservation of Brassica vegetables has received much attention for improving their nutritional and commercial value. In this study, carboxymethyl cellulose (CMC)-based cross-linking coating embedded with liquid paraffin was prepared to preserve fresh pakchoi (Brassica chinensis L.) and its effects on postharvest water loss, quality and reactive oxygen species (ROS) metabolism were evaluated. Results showed that ionic cross-linking and liquid paraffin reinforced the structure compactness and water barrier property of CMC coating by uniformly distributing liquid paraffin in cross-linking network. The novel CMC-based coating effectively reduced water loss and improved appearance and nutrition of fresh pakchoi stored at 25 °C and 60 % relative humidity for 48 h. Furthermore, the coating treatment enhanced ROS scavenging capacity and reduced lipid peroxidation, which was attributed to the improvement of antioxidant enzyme activities, ascorbate-glutathione cycle and phenylpropanoid metabolism. This work demonstrates that the novel CMC-based water barrier coating is promising to control the water loss of pakchoi and further maintain the whole quality by regulating ROS metabolism.