Anthocyanin-based intelligent food packaging films reinforced with ginger pseudostem cellulose fibers: a sustainable approach for real-time freshness monitoring of perishable foods.

This study aimed to fabricate a poly(vinyl alcohol) (PVA)-based intelligent indicator by combining anthocyanin-rich extracts from purple passion fruit peel (PPFP) with cellulose fibers extracted from ginger pseudostem (GP). Anthocyanins were obtained from PPFP via ultrasound-assisted extraction (UAE), achieving a maximum content of 1.53 mg cyanidin-3-O-glucoside equivalents (C3G)/g dry weight (DW) under optimized conditions. Cellulose fibers (CFs) extracted from GP through chemical treatment exhibited high purity, enhanced thermal stability, and a crystallinity index of 74.65%. The effects of anthocyanin incorporation and CF reinforcement at different levels on the structural characteristics, physicochemical properties, and pH-responsive color behavior of the films were evaluated. The result showed that the smart film reinforced with 1.0 wt% CFs exhibited reduced water vapor permeability (WVP), decreasing from 3.39 to 2.95 (×10-10 g m-1 s-1 Pa-1) compared to the film containing only anthocyanin. The mechanical properties of the films were enhanced upon the incorporation of anthocyanin and reinforcement with 1.0 wt% CFs, as evidenced by increases in tensile strength (from 21.09 to 32.21 MPa), elongation at break (from 261.06% to 404.68%), and Young's modulus (from 91.72 to 97.05 MPa). The practical applicability of the films was evaluated by monitoring the freshness of refrigerated shrimp, during which distinct color changes from pinkish-brown to green were observed in response to freshness deterioration. Overall, the developed intelligent films demonstrate strong potential for monitoring the freshness of perishable foods, including meat and seafood, thereby contributing to improved food quality assurance and consumer safety.