Harnessing pomegranate rind waste to develop novel bioactive packaging films using citric acid crosslinked polyvinyl alcohol (PVA)/starch-based polymer matrix

The current study explores the use of pomegranate rind waste to prepare methanolic pomegranate rind extract (PRE) and its incorporation into a citric acid crosslinked PVA/starch matrix for the development of bioactive packaging films. The characterization of PRE using FT-IR and GC-MS confirmed the presence of phenolic compounds and the total phenolic content was measured to be 380 mg/g via the Folin-Ciocalteu method. Initial crosslinking of the PVA/starch matrix with citric acid was verified by FT-IR analysis, resulting in enhanced mechanical strength, UV light barrier properties and reduced wettability of the films. FT-IR and AFM analyses demonstrated interactions between PRE and the polymer matrix. The surface topography of the polymeric films was assessed through SEM and AFM. The incorporation of PRE (0.5-4%) into the crosslinked matrix significantly improved tensile strength (6.15-8.43 MPa), elongation at break (22.14-29.5%) and UV light barrier properties (< 5%). The increase in water contact angle (WCA) with PRE incorporation indicated increased hydrophobicity, with all films exhibiting WCA values above 90 degrees. The crystallinity of films was accessed by XRD analysis which confirmed that the addition of PRE reduced the crystallinity of the films. Also, the addition of PRE imparted antioxidant and antimicrobial properties to the films. The free radical scavenging activity against DPPH radicals was about 57.26-72.90% while the antimicrobial efficacy against gram-positive and gram-negative bacteria measured through the zone of inhibition was found to be 6.31-11.02 mm and 5.03-10.80 mm respectively. These findings suggest that citric acid crosslinked PVA/starch films infused with PRE have significant potential as innovative bioactive packaging materials for the food industry.