Abstract:
To develop intelligent, green fish freshness-indicating films, we evaluated the physicochemical properties (Mechanical strength, moisture barrier capability, thermal stability, and antioxidant activity) of chitosan titanium dioxide (CS-TiO
2) composite particle perilla essential oil lotion with different addition levels (1%, 3%, 5%, and 7%, w) and the freshness-indicating films (EP1, EP3, EP5, and EP7) prepared from curcumin and gelatin. Additionally, we assessed the preservation efficacy of the films on golden pomfret (
Trachinotus ovatus) by monitoring total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), carbonyl content, total sulfhydryl content, antibacterial activity, and freshness-indicating performance. Pure gelatin film (EP0) served as the control. Results demonstrate that all CS-TiO
2-incorporated films exhibited significantly enhanced properties compared with EP0. EP7 films exhibited excellent mechanical properties (Tensile strength 38.34 MPa, elongation at break 25.80%) and moisture resistance (Dissolution rate 32.16%, swelling rate 152.18%). They also demonstrated outstanding barrier properties (Water vapor transmission rate 3.04×10
−13 g·m
−1·s
−1·Pa
−1) and antioxidant activity (DPPH scavenging rate 45.97%, ABTS scavenging rate 87.36%). When applied to the refrigerated preservation of golden pomfret, the films effectively inhibited fish spoilage. After 7 d, TVB-N and TBARS values were controlled at 22.36 mg·100 g
−1 and 0.53 mg·kg
−1, respectively, while significantly maintaining protein oxidation stability (Carbonyl content 55.89 μmol·mg
−1, total sulfhydryl content 48.86 μmol·mg
−1). For freshness indication, the EP7 group exhibited significant color changes from pale yellow to russet with prolonged storage, correlating with freshness deterioration. Therefore, curcumin and perilla essential oil emulsion-based freshness-indicating films in this research can not only extend the shelf life, but also intelligently indicate the freshness of fish.