Smart and sustainable PVA/cellulose-ZnO/anthocyanin Films: Dual-action packaging for extended shelf life and real-time freshness detection

Abstract

Sustainable sensing films for intelligent packaging applications are the need of the hour. Herein, for the first time, cellulose nanofibers (CNFs) from pineapple pomace are used as the host polymer for preparing cellulose-ZnO (C–ZnO) powder. The structural and dimensional properties of the C–ZnO powder were confirmed using different characterization techniques. Red cabbage-derived anthocyanin and C–ZnO were infused with polyvinyl alcohol (PVA) to make the antibacterial sensing films (C–ZnO/PVA (CPVA) and C–ZnO/anthocyanin/PVA (CAPVA)). The effective bonding between the PVA and the fillers is studied using the AT-FTIR analysis. The incorporation of C-ZnO and C–ZnO/anthocyanin resulted in the improving the UV screening ability of the developed films. The tensile strengths of the CPVA and CAPVA films were 14 and 11 % greater than that of the neat PVA film. The interaction with water was significantly reduced when C–ZnO was added to PVA making the material more hydrophobic. This was further confirmed using wettability studies. In 100 days, in wet conditions, the PVA, CPVA, and CAPVA showed biodegradability of 17, 37, and 39 %, respectively. As a packaging material, CPVA and CAPVA films increased the shelf life of fresh shrimp by up to 4 days as they have significant water barrier properties and antibacterial activity with an inhibitory zone of 28 and 20 mm (for CAPVA) against S. aureus and E. coli respectively. Furthermore, the release of volatile amines from shrimp spoilage caused the color of the CAPVA films to change over time from pink to yellow, indicating the possibility of using these films for real-time freshness monitoring.