Fabrication and characterization of a pH-sensitive indicator film by purple basil leaves extract to monitor the freshness of chicken fillets

Abstract

This research aimed to fabricate an intelligent film using bovine gelatin and purple basil leaf extract (PBLE). Then the application of the film was investigated to monitor the freshness of chicken fillets. The films were prepared by casting the bovine gelatin solution (75 g/L) with glycerol (30% of dried gelatin) on glass plates and were dried under controlled conditions. PBLE was incorporated into gelatin films (0, 100, 200, and 300 mg anthocyanin from PBLE/kg dried gelatin), and the film characteristics, including physicochemical, antioxidant, antimicrobial, anthocyanin release, and color variations due to pH change, were investigated. The results indicated that the films containing PBLE had a higher thickness, solubility, total phenol content, and antioxidant activity than the control film. The addition of extract improved the antibacterial activity of gelatin films. The release kinetics study showed that the release of anthocyanin from the film was slow, and after 200 min, about 26% of the total anthocyanin content was released from the film. The fabricated films indicated significant color changes from purple to green as pH changed from 4 to 9. The pH-sensitive indicator film also changed from purple to green with TVB-N development (from 8 to 38 mg/100 g) during the storage period of chicken fillets. Therefore, the bovine gelatin-based film containing PBLE can be used as a freshness indicator of chicken fillets.