Characteristics of Intelligent Film based on Glucomannan Porang (Amorphophallus oncophyllus) and Gelatin with Addition of Copigmented Anthocyanins from Rambutan Peel for Shrimp Freshness Monitoring

This study develops intelligent films from porang-derived glucomannan and gelatin enriched with RPAE (native and gallic-acid-copigmented) for shrimp freshness monitoring. The films showed improved performance, TS up to 9.37 MPa, EAB up to 31.90%, and WVP of 3.10-4.72×10⁻7 g·m⁻1·Pa⁻1·h⁻1 together with enhanced radical-scavenging activity. FTIR indicated hydrogen-bonding interactions among gelatin, glucomannan, and anthocyanins, while SEM revealed smoother, more homogeneous morphologies for copigmented systems. The films exhibited a clear pH-dependent optical response with visually perceptible shifts (ΔE > 5). During shrimp storage, TVB-N increased from 28.11 to 71.03 mg N/100 g and TVC from 5.24 to 6.27 log CFU/g; the film color transitioned from green to yellow in parallel with quality deterioration, enabling non-invasive, real-time indication of spoilage. Leveraging locally abundant biopolymers and colorants, these films advance sustainable, intelligent packaging for seafood quality and safety. HIGHLIGHTS Intelligent films were developed from the polymers of glucomannan, gelatin enriched with anthocyanins from rambutan peel The incorporation of anthocyanins improved several characteristics of the films, including thickness, TS, EAB, WVP, and RSA as measured by DPPH and ABTS assays Their colorimetric response to pH changes was clearly visible to the naked eye, shifting from pink to yellow and green with increasing pH Intelligent films containing copigmented RPAE also exhibited smoother morphology with fewer cracks FTIR analysis confirmed the formation of hydrogen bonds between gelatin, glucomannan, and RPAE The intelligent films served as freshness indicators for shrimp, exhibiting a distinct color transition from green to yellow in response to increasing pH. GRAPHICAL ABSTRACT