fabrication smart ph bionanocomposite film based on biocompatible polymer and roslle calyx extract/nano-zinc oxide for monitoring rainbow trout fillets

This work aimed to make a smart biofilm based on tapioca starch/bovine gelatin and roselle calyx extract (rce)/nanofiller-zno. then the utilization of the biofilm was studied to monitor the rainbow trout fillets. the biofilms were fabricated by casting the starch/gelatin solution with sorbitol /glycerol (3.2g) on casting plates and were dried at 25°c. rce was added into biofilms (0.5 g for tp/rce/zno-n and 2g for tp/rce), and the biofilm characteristics, such as thickness, color, and antioxidant properties were investigated. the films containing nanofiller-zno/rce and rce showed significantly (p<0.05) more antioxidant activity than the neat film which respective values of 18.31 11.42 and 3.1. the thickness of the smart films significantly increased (p<0.05) from 0.08 to 0.13 by the addition of rce/nanofiller zno into the solution. according to the results, a* value was significantly higher (p<0.05) in smart film with nanofiller-zno/rce and rce. the lowest l* value was obtained in film with nanofiller-zno/rce. at the end of the conservation, the tvb-n value reached 35.7 mg n/100 and with the tvb-n significantly increase (p<0.05), the color properties of the smart films also changed. the color of the biofilm was purple, but the a* value significantly decreased. therefore, the film based tapioca starch/bovine gelatin/nanofiller zno/rce can be applied as a natural indicator of rainbow trout fillets.