UV-irradiated gelatin-chitosan bio-based composite film, physiochemical features and release properties for packaging applications

3D printing cassava starch-ovalbumin intelligent labels: Co-pigmentation effects of gallic acid on anthocyanins

Anthocyanins are often chosen as signal converters of intelligent labels. However, they are degraded by high-temperature oxidation in the process of intelligent label preparation. The color fading seriously affects the sensitivity of color development. In this study, a green 3D printing intelligent label preparation technique was developed, in which gallic acid (GA) was added to a blueberry anthocyanin (BA) solution to enhance the color of the co-pigment to ensure the color sensitivity. The combined effect of GA-BA reduced the fade rate of the anthocyanins from 35.13 % to 26.44 % at 90 °C. The printing ink has shear-thinning viscosity characteristics and yield stresses in the range of 500-600 MPa for high-quality printing. Structural analysis revealed that GA-BA co-pigmentation enhanced the interaction between ovalbumin and cassava starch. In addition, the method of 3D printing to prepare labels was conducive to solving the problem of waste in traditional labeling process. The results of freshness testing of sea shrimp proved that labels can be applied to fresh boxes to reflect the freshness of food. We provide a method for enhancing the color of 3D-printed smart ink to prepare intelligent labels with reproducible and customizable batch shapes.

UV Radiation and Protein Hydrolysates in Bio-Based Films: Impacts on Properties and Italian Salami Preservation

UV radiation was combined with the incorporation of fish protein hydrolysates to improve the performance of active bio-based films for food packaging. UV radiation was not used previously to enhance the packaging performance of blend films of starch/protein, and fish protein hydrolysates were not incorporated in bio-based polymer surfaces previously. Rice starch and fish proteins (from Whitemouth croaker muscle) were utilized to prepare films by the casting technique, which were UV-radiated under different exposure times (1, 5, and 10 min). The packaging performance of the films was determined according to the mechanical and barrier performance, solubility, and color. Fish protein hydrolysates (from Argentine croaker muscle) were then incorporated into the films (bulk structure or surface). The results showed that UV radiation for 1 min increased the tensile strength and modified the optical properties of films. It also altered the structure of the polymeric matrix, as demonstrated by the microstructure and thermal analysis, in agreement with the data obtained in packaging properties. The evaluation of antioxidant capacity through 2,2-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and reducing power indicated that incorporating fish protein hydrolysates either in the films' bulk structure or film surface promoted antioxidant properties; control films (produced with rice starch/fish proteins without hydrolysates) also presented antioxidant potential. According to the peroxide value and thiobarbituric acid reactive substance (TBARS) assays, control films and the films containing hydrolysates in their bulk structure or on the surface could prevent the lipid oxidation of Italian salami. Thus, combining UV radiation to shape the characteristics of bio-based materials with fish protein hydrolysates to reduce lipid oxidation contributes to the performance of active bio-based films for food packaging.

Different crosslinking as a strategy to improve films produced from external mesocarp of pequi (Caryocar brasiliense)

The pequi (Caryocar brasiliense) external mesocarp is rich in phenolic compounds and pectin and demonstrates the potential to produce active and biodegradable films. Thus, the present study aimed to produce films with pequi mesocarp as a polymer matrix and evaluate the influence of crosslinking agents (calcium chloride and citric acid) on the film's properties. The films obtained from pequi mesocarp (MF), showed in general, complete biodegradation in 33 days, good antioxidant capacity, and inhibition against S. aureus (24.7 mm) and E. coli (23.0 mm). The crosslinking agents reduced solubility by up to 35% and increased the elongation of the films by up to 3.5-fold. Calcium chloride promoted a higher reduction in solubility, and both agents increase the antioxidant and antimicrobial activities, compared to MF. Citric acid proved to be the best agent to modify the properties of pequi mesocarp films. In addition to the crosslinking action, it presented plasticizing effect.

Colorimetric food spoilage monitoring with carbon dot and UV light reinforced fish gelatin films using a smartphone application

The objective of this study was to develop novel colorimetric films for food freshness monitoring. UV light irradiation (365 nm) and carbon dots (CDs) were tested as the potential crosslinkers in the fabrication of anthocyanins doped fish gelatin (FG) films. The effect of crosslinkers on the optical, surface, structural, barrier and mechanical properties of FG films was investigated. The incorporation of CD under UV irradiation improved the tested properties of FG films. The kinetic colorimetric responses of FG films against ammonia vaporwere studied to simulate the food spoilage and determine the ammonia sensitivity of the films. Among the tested films, UV-treated FG films containing 100 mg/l (FG-UV-CD100) indicated the best properties. Later, the color difference of FG-UV-CD100 films was observed to correlate well with microbial growth and TVB-N release in skinless chicken breast samples. At the same time, a custom-designed smartphone application (SmartFood) was also developed to be used with the FG-UV-CD100 film for quantitative estimation of food freshness in real-time. The proposed food freshness monitoring platform reveals a great potential to minimize global food waste and the outbreak of foodborne illness.

High antibacterial activity of chitosan films with covalent organic frameworks immobilized silver nanoparticles

In this study, chitosan (CS) film containing covalent organic frameworks (COFs) immobilized silver nanoparticles (AgNPs) were developed for food packaging with improved antibacterial activities and film properties. COFs-AgNPs were fabricated via in-situ synthesis of immobilizing AgNPs on COFs. Transmission electron microscope, Zeta potential, X-ray diffraction, element mapping and Fourier transform infrared spectroscopy confirmed the successful fabrication of COFs-AgNPs, and COFs-AgNPs showed superior antibacterial activity against S. aureus and E. coli. Furthermore, the as-prepared COFs-AgNPs composite was further used to fabricate CS composite films (CS/COFs-AgNPs) by a solution casting method. The findings showed that the tensile strength of the nanocomposite films enhanced dramatically with the increase of the COFs-AgNPs content, while the UV-visible light barrier property, water swelling and solubility properties, and water vapor permeability (WVP) decreased significantly. Not only that, the CS/COFs-AgNPs nanocomposite films also showed outstanding antibacterial activity and effectively prolonged the storage time of white crucian carp (Carassius auratus). As a result, CS/COFs-AgNPs nanocomposite films show great potential in active food packaging.

Development of novel collagen hydrolysate bio-nanocomposite films extracted from hide trimming wastes reinforced with chitosan nanoparticles

The wide availability of pollutant by-products from the leather industries has been a key factor in driving the research into converting these low-cost by-products into high value-added collagen-based products. In this study, collagen hydrolysate (CH) was extracted from hide trimming waste from the tanneries and used to prepare biodegradable films with chitosan nanoparticles (CNPs) with different concentrations to develop an alternative product to non-biodegradable plastics. The effects of CNPs concentration on the thickness, mechanical, water barrier, thermal, light transmittance, color properties, and opacity of CH-based films were investigated. The results clearly show that the tensile strength and elastic modulus values of CH/CNPs films increase significantly as the concentration of CNPs increases, while the elongation at break, water solubility, and water vapor permeability values decrease. In addition, scanning electron microscopy (SEM) showed uniform distributions of CNPs in the CH-based films. Based on the results obtained, the extraction of CH from hide trimming wastes and reuse in the production of biodegradable films will both prevent these valuable wastes from being dispose into the landfills and will be an alternative to fossil-derived plastics in the future.