Browning mechanism in stems of fresh‑cut lettuce

•Cellular fluids released from the cut stem are the primary cause of browning.•Mass levels of ROS production have an indirect effect on stem browning.•The browning of cellular fluids was mainly related to the PAL activity increased.•The stem browning was related to unsaturated fatty acids content decreased.•A sufficient supply of energy can maintain the activity of antioxidant enzymes.