Abstract:In this study, blueberry anthocyanin (BA) as the freshness indicator, corn starch (CS) and carboxymethyl cellulose(CMC) were used as film-forming substrates to prepare smart indicator films by casting. The effects of different mass fraction of anthocyanins on the mechanical properties, moisture content, water vapor transmittance, thermal stability, infrared spectrum, surface microstructure and sensitivity of the composite film were analyzed and compared. The results showed that when the BA mass fraction was 3%, the elongation at break of the indicator film was the highest, the moisture content and water vapor transmission rate were the lowest, and the sensitivity was the best. When the BA mass fraction was 18%, the tensile strength was the highest, and the thermal stability was the best. Fourier transform infrared spectroscopy and scanning electron microscopy showed that the BA had good compatibility with the other two film-forming substrates and could improve the intermolecular compatibility. The indicator film was used to monitor the freshness of beef at 25 ℃. The total volatile basic nitrogen content was 15.94 mg/100 g after 24 h, indicating the occurrence of beef spoilage. At the same time, the color of the indicator film changed to light purple, and changed to light blue after 48 h storage. The research results could provide reference for the development and application of blueberry anthocyanin intelligent indicator films.