Abstract:To explore the application effect of active-intelligent packaging materials in fruit preservation，a sodium alginate-chitosan bilayer film was prepared with anthocyanin extracted from purple sweet potatoes by vacuum freeze-drying as the indicator. Then，this study evaluated the effects of varying anthocyanin addition amounts on film properties （including dissolution，barrier，and optical properties） and pH response performance，as well as the preservation effect of the film on blueberries. Results showed that the addition of anthocyanin improved the overall physical properties of the film，which was realized by increasing the film thickness，water vapor permeability，and oxygen permeability，as well as the visible light-ultraviolet barrier properties and hydrophobicity of the film，while reducing the water content，water solubility，and swelling properties of the film. In addition，the bilayer film demonstrated significant color responses across the pH value range of 2-13，shifting colors from red to pink，purple，blue，green，and yellow. The blueberry preservation test results indicated that the addition of anthocyanin reduced the weight loss and decay rate of the film-covered blueberries during storage，and slowed down the decrease in hardness，soluble solid content，and titratable acid content.Therefore，anthocyanins endowed the bilayer film with good performance in maintaining the quality and extending the shelf life of blueberries.