The effects of zinc oxide nanoparticles (ZnONPs) on the properties of rice starch–gelatin (RS–G) films were investigated. ZnONPs were synthesized by a green method utilizing Asiatic pennywort (Centella asiatica L.) extract. The ZnONPs were rod-shaped, with sizes ranging from 100–300 nm. An increase in the concentration of ZnONPs significantly (p < 0.05) increased the thickness (0.050–0.070 mm), tensile strength (3.49–4.63 MPa), water vapor permeability (5.52–7.45 × 10⁻¹¹ g m/m² s Pa), and thermal stability of the RS–G–ZnONPs nanocomposite films. On the other hand, elongation at break (92.20–37.68%) and film solubility (67.84–30.36%) were significantly lower (p < 0.05) than that of the control RS–G film (0% ZnONPs). Moreover, the addition of ZnONPs strongly affected the film appearance, color, transmission, and transparency. The ZnONPs had a profound effect on the UV-light barrier improvement of the RS–G film. The crystalline structure of the ZnONPs was observed in the fabricated nanocomposite films using X-ray diffraction analysis. Furthermore, the RS–G–ZnONPs nanocomposite films exhibited strong antimicrobial activity against all tested bacterial strains (Staphylococcus aureus TISTR 746, Bacillus cereus TISTR 687, Escherichia coli TISTR 527, Salmonella Typhimurium TISTR 1470) and antifungal activity toward Aspergillus niger. According to these findings, RS–G–ZnONPs nanocomposite film possesses a potential application as an active packaging: antimicrobial or UV protective.

Mantis shrimp (Oratosquilla nepa) exoskeleton, a leftover generated after processing, was used as a starting material for chitosan (CS) production. CS was extracted with different deacetylation times (2, 3 and 4 h), termed CS−2, CS−3 and CS−4, respectively, and their characteristics and antimicrobial and film properties with agarose (AG) were investigated. Prolonged deacetylation time increased the degree of deacetylation (DDA: 73.56 ± 0.09–75.56 ± 0.09%), while extraction yield (15.79 ± 0.19–14.13 ± 0.09%), intrinsic viscosity (η: 3.58 ± 0.09–2.97 ± 0.16 dL/g) and average molecular weight (M_ν: 1.4 ± 0.05–1.12 ± 0.08 (×10⁶ Da)) decreased (p < 0.05). FTIR spectra of extracted CS were similar to that of commercial CS. Among all the CS samples prepared, CS−3 had the best yield, DDA, M_ν and antimicrobial activity. Therefore, it was chosen for the development of composite films with AG at different ratios (CS−3/AG; 100/0, 75/25, 50/50, 25/75 and 0/100). As the proportion of AG increased, the tensile strength (29.96 ± 1.80–89.70 ± 5.08 MPa) of the composite films increased, while thickness (0.056 ± 0.012–0.024 ± 0.001 mm), elongation at break (36.52 ± 1.12–25.32 ± 1.23%) and water vapor permeability (3.56 ± 0.10–1.55 ± 0.02 (×10⁻⁷ g m m⁻² s⁻¹ Pa⁻¹)) decreased (p < 0.05). Moreover, lightness of the films increased and yellowness decreased. CS−3/AG (50/50) composite film exhibited high mechanical and barrier properties and excellent compatibility according to FTIR and SEM analyses. According to these finding, mantis shrimp exoskeleton could be used to produce CS. The developed bio-composite film based on an appropriate ratio (50/50) of CS−3 and AG has potential for being used as food packaging material.

The effects of green tea extract (GTE) at varying concentrations (0.000, 0.125, 0.250, 0.500, and 1.000%, w/v) on the properties of rice-starch-pectin (RS-P) blend films were investigated. The results showed that GTE addition enhanced (p < 0.05) the antioxidation properties (i.e., total phenolic content, DPPH radical scavenging activity, and ferric reducing antioxidant power) and thickness of the RS-P composite film. The darker appearance of the RS-T-GTE blend films was obtained in correspondence to the lower L* values. However, the a* and b* values were higher toward red and yellow as GTE increased. Though GTE did not significantly alter the film solubility, the moisture content and the water vapor permeability (WVP) of the resulting films were reduced. In addition, the GTE enrichment diminished the light transmission in the UV-Visible region (200–800 nm) and the transparency of the developed films. The inclusion of GTE also significantly (p < 0.05) lowered the tensile strength (TS) and elongation at break (EAB) of the developed film. The FT-IR spectra revealed the interactions between RS-P films and GTE with no changes in functional groups. The antimicrobial activity against Staphylococcus aureus (TISTR 764) was observed in the RS-P biocomposite film with 1% (w/v) GTE. These results suggested that the RS-P-GTE composite film has considerable potential for application as active food packaging.

Green mussel shells (Perna viridis) are generated in huge amounts and discarded as waste materials. Such waste may be used to produce biopolymer materials such as chitosan. The physicochemical properties of chitosan prepared from different sizes of green mussel shells (small size (CHS): ≤5.00 cm in length and big size (CHB): >5.01 cm in length) were characterized and compared with commercial chitosan (CH). Furthermore, the mechanical and physicochemical properties of the blended films were also investigated. The results of the physicochemical properties showed that CHS and CHB were quite different from CH. The degree of deacetylation of CHS, CHB, and CH was found to be 32.71%, 52.56%, and 70.42%, respectively (p < 0.05). The water- and fat-binding capacities of CH were higher than those of CHS and CHB. Structural differences between CHS, CHB, and CH were studied using Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Significant increases in thickness, water vapor permeability, and strength of the blended films were found when the extracted chitosan was added (p < 0.05). However, further study is needed to improve the chitosan extraction process, which can enhance the physicochemical properties of the obtained chitosan and be widely used in many industries.

This study aimed to evaluate the response efficiency of colorimetric indicator films based on carboxymethyl cellulose (CMC) incorporated with different anthocyanins [Karanda alone (CMC/AK), butterfly pea alone (CMC/AB), and a mixture of anthocyanins from Karanda and butterfly pea (CMC/AK75/AB25)] for tracking shrimp freshness during storage at different temperatures and times (4 °C for 8 days and 25 °C for 30 h). The mathematical models were also applied to predict their freshness and shelf life. The CMC/AK75/AB25 indicator film was the most sensitive and clearly changed color, which could be distinguished by the naked eye. Color changes indicated the shrimp deterioration processes: dark purple (fresh), purplish gray or gray (semi-fresh), and olive green or brown (spoilage). During shrimp storage at temperatures of 4 and 25 °C, the pH reached 7.52 and 8.14, TVB-N 35.98 and 72.72 mg/100 g, and TVC 5.75 and 7.88 log CFU/g, respectively, indicating shrimp had completely deteriorated. Furthermore, there was a positive correlation between the ΔE value of the indicator film and both TVB-N and TVC. These findings suggest that the CMC/AK75/AB25 indicator film could serve as a real-time visual indicator for tracking shrimp freshness and could enhance the guarantee of shrimp safety.