Development of curcumin-containing polyvinyl alcohol/chitosan active/ intelligent films for preservation and monitoring of Schizothorax prenanti fillets freshness

Active/intelligent films for the preservation and monitoring of Schizothorax prenanti fillets freshness were prepared by combining curcumin (CUR) with polyvinyl alcohol/chitosan (PVA/CS) matrix. SEM images showed that the CUR with a maximum content of 1.5 % (w/w) was evenly distributed in the composite matrix. The addition of CUR did not affect the chemical structure of PVA/CS matrix, as confirmed by FTIR investigation. When 1.5 % (w/w) CUR was added, the water vapor barrier property, tensile strength and antioxidant activity of the composite film were the best, which were 5.38 +/- 0.25 x 10(-11) g/m<middle dot>s<middle dot>Pa, 62.05 +/- 1.68 MPa and 85.50 +/- 3.63 %, respectively. Water solubility of PVA/CS/CUR-1.5 % film was reduced by approximately 27 % compared to PVA/CS film. After adding CUR, the antibacterial properties of the composite film increased significantly. Although the addition of CUR reduced the biodegradability of PVA/CS film, the PVA/CS/CUR-1.5 % film degraded >60 % within 5 weeks. By measuring pH, weight loss, total volatile base-nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and total viable counts (TVC), the preservation effect of the composite films on the fish freshness was evaluated. The fish shelf life treated by PVA/CS/CUR-1.5 % film expanded from 3-6 days to 12-15 days at 4 degrees C. In addition, when PVA/CS/CUR-1.5 % film was used to monitor the fish freshness, it exhibited clear color fluctuations, from yellow to orange and to red, corresponding to first-grade freshness, second-grade freshness, and rottenness of the fish, respectively. As a result, the films can be successfully used for Schizothorax prenanti fillets preservation and deterioration monitoring.