Abstract: with the compound polymer coating included in the polymer material,the food antiseptic and the antioxidizer.to coat lichi was investigted to store at room temperature.the results showed that the compound polymer coating could reduce the evaporation and the respiratory rate of the fruit.Among the polymer materials cchitosan,a natural polymer agent,had the optimal keeping,and the best concentration of chitosan solution was 2%.in this concentration the coating quality could meet the need of the stored litchi satisfactorily.By the determination on the polyphenol oxydase (PPO)activity of litchi,the further investigation showed that the activity of PPO could gradually decrease the deepenind of brown changing on the litchi rind.The rate of brown changing in the coated litchi was obviously slower than that in the not coated fruit.

Key words: Compound polymer coating , Preserved litchi , Polyphenol oxydase activity