Chitosan, with an average deacetylation of 93% and molecu- lar weight of 100 kD (Golden-Shell Biochemical, Yuhuan, China), was dissolved in 2% acetic acid by stirring at room temperature overnight to obtain 1% chitosan/acetic acid solutions. Chitosan treatment was carried out at room temperature by dipping the apples in 1% chitosan/acetic acid solution or 2% acetic acid solution (as control) for 10 min and allowed to air dry at room temperature (Wang et al., 2014). After air drying, apple fruit were put into plastic baskets, overlapped with plastic wrap and stored at 20 ◦ C with a rel- ative humidity of 95% for 15 days. Each treatment contained three replicates with 20 fruits per replicate. Fruit quality and proteomic analysis were conducted at 5, 10 and 15 days after storage.