In order to find out the concentration and dipping time of acid-chitosan coating solution for treating “Tieu Da Bo” longan fruits to reduce browning and maintain good quality during storage, an investigationwas carried out in a completely randomized factorial design with two factors by dipping longan fruits in 0
0.2
0.3
0.4% chitosan coating solution containing 0.3 N citric acid (pH 3.3) for 1, 3 and 5 minutes. The treated fruits in each treatment were then packaged in PE bag with 0.035mm thickness and stored at 5°C,80-95% RH for 26 days, and observations of fruit quality during storage were taken place. Results indicated that 0.2% chitosan solution containing 0.3 N citric acid (pH 3.3) for 3 minutes could retard skin color changes with the lowest browning grade and disease percentage, and high L* value compared to the others. Based on browning grade, the fruits treated with 0.2% chitosan (pH 3.3) were still acceptable after 26 days of storage, while other treatments on fruits were not acceptable. In addition, weight loss and internal quality did not change much during storage.