Effects of citric acid crosslinking on the structure and properties of ovotransferrin and chitosan composite films

Chitosan/teff flour active films incorporated with citric acid and beetroot leaf extract: Physicochemical properties and mathematical modeling of phenolic release

Active compounds are integrated into food packaging films to enhance their food protection capabilities. Understanding the release of these components in films, particularly in crosslinking scenarios, is crucial. This study aimed to mathematically model the release of phenolic compounds from chitosan/teff flour films to understand how active compounds gradually release. Moreover, it was aimed to study the effects of incorporation of beetroot leaf extract and citric acid crosslinking. The collective observations, encompassing increased density and thermal stability, alongside concurrent reductions in moisture content, water solubility, water vapor permeability and swelling index following citric acid addition, strongly suggested the presence of crosslinking. Applying Fick's law and the finite element method revealed a substantial influence of the crosslinking agent on diffusion coefficients. The model exhibited strong agreement with experimental data, as reflected in low root mean square error values ranging from 3.02 to 8.50 mmol/m3 for films. Furthermore, the influence of citric acid crosslinking on the release of TPC was evident, as indicated by a decrease in average diffusion coefficient values from 3.499 × 10-13 m2 s-1 to 1.770 × 10-13 m2 s-1 with the formula with 1.5 % citric acid and 0.5 % beetroot leaf extract. This showcases the impact of various parameters on controlled release in food packaging.

Engineering eco-friendly and biodegradable biomass-based multifunctional antibacterial packaging films for sustainable food preservation

The study presents a new class of eco-friendly and biodegradable biomass-based multifunctional antibacterial packaging films (G-OCSI) based on oxidized corn starch-based nonionic biopolymer (OCSI) and gelatin (Gel), and investigates the effects of different OCSI contents on the properties of G-OCSI. The results demonstrated that G-OCSI 0.25 had good water vapor barrier properties, antioxidant activity (DPPH RSA: 85.84 %), UV resistance (UV blocking > 99.9 %), water resistance (WCA: 122.30°), and tensile properties. Based on the disk diffusion experiment, G-OCSI exhibited significant bactericidal and antibacterial effects against S. aureus and E. coli. Moreover, G-OCSI had good biodegradability in natural environments, and could obviously accelerate the crops growth. Finally, a banana preservation experiment confirmed that G-OCSI could significantly extend the shelf life of bananas at room temperature at least 3 days. The biodegradable packaging films not only realizes the sustainable utilization of biomass resources but also has the potential to replace traditional petroleum-based plastics.

Natural polysaccharides and proteins-based films for potential food packaging and mulch applications: A review

Conventional nondegradable packaging and mulch films, after reaching the end of their use, become a major source of waste and are primarily disposed of in landfills. Accumulation of non-degradable film residues in the soil leads to diminished soil fertility, reduced crop yield, and can potentially affect humans. Application of degradable films is still limited due to the high cost, poor mechanical, and gas barrier properties of current biobased synthetic polymers. In this respect, natural polysaccharides and proteins can offer potential solutions. Having versatile functional groups, three-dimensional network structures, biodegradability, ease of processing, and the potential for surface modifications make polysaccharides and proteins excellent candidates for quality films. Besides, their low-cost availability as industrial waste/byproducts makes them cost-effective alternatives. This review paper covers the performance properties, cost assessment, and in-depth analysis of macromolecular structures of some natural polysaccharides and proteins-based films that have great potential for packaging and mulch applications. Proper dissolution of biopolymers to improve molecular interactions and entanglement, and establishment of crosslinkages to form an ordered and cohesive polymeric structure can help to obtain films with good properties. Simple aqueous-based film formulation techniques and utilization of waste/byproducts can stimulate the adoption of affordable biobased films on a large-scale.

Precise control of aggregation morphology: Effective strategy to tune the properties of ovotransferrin particles

Different aggregation morphologies of ovotransferrin (OVT) aggregates were successfully obtained through precise control, and the effects on structural, physical, liquid-liquid and gas-liquid interfacial characteristics as well as mechanisms were explored for the first time. It was observed that the surface hydrophobicity of OVT fibrils was higher than OVT spheres due to the acid-heat treatment. The exploration of liquid-liquid interface behaviors indicated that OVT fibrils possessed higher adsorption capacity at the interface, revealing the higher surface activity at the oil-water interface. During adsorption process, fibrils exhibited higher diffusion rate, while spheres were easier to penetrate and rearrange at the interface. The interfacial film composed of fibrils possessed more elastic solid-like behaviors owing to the higher surface activity of individual fibrous aggregates and rapid fibril-fibril interactions. The analysis of gas-liquid interface characteristics presented that OVT spheres possessed lower interfacial tension and higher interfacial viscoelasticity, and showed significantly higher FC and FS values in comparation to fibrils. These findings will facilitate the reader's understanding of the relationship between protein aggregate structure and properties, and lay a foundation for broadening the application of OVT and even other proteins.

Superwettable cellulose acetate-based nanofiber membrane with spider-web structure for highly efficient oily water purification

Electrospinning nanofibers membrane has received much attention to remove the insoluble oil from the sewage, while the poor mechanical strength and low oil/water separation efficiency of membranes limit their practical application. Here, we prepared a superwettable deacetylated cellulose acetate (d-CA)-based electrospinning nanofibers membrane simply dipped by bacterial cellulose (BC) and cross-linked with citric acid (CCA) to construct the spider-web structure spontaneously. Compared with the pristine d-CA membrane, the obtained d-CA/BC@CCA membrane exhibits the remarkable oil/water separation performance. The flux and separation efficiency of n-hexane/water emulsion without (SFE) and with (SSE) emulsifier for d-CA/BC@CCA membrane are 9364 L·m-2·h-1·bar-1, 98.34 % and 5479 L·m-2·h-1·bar-1, 99.39 %, respectively, which are mainly attributed to the improved hydrophilicity of its surface and the decreased pore sizes caused by the unique spider-web structure. In addition, d-CA/BC@CCA membrane also possesses the outstanding mechanical properties, the better cycle stability, as well as the excellent durability. This study provides a novel strategy for the construction of the high-performance oil/water separation membrane.

Production of PVA-chitosan films using green synthesized ZnO NPs enriched with dragon fruit extract envisaging food packaging applications

In this work, the PVA-chitosan composite packaging films doped with biomass-fabricated zinc oxide nanoparticles (ZnO NPs) and dragon fruit waste extract (DFE) were developed for potential use in food packaging applications. ZnO NPs were synthesized using a sustainable method employing C. sinensis waste extract as a reducing agent. Chitosan and PVA were blended in a specific ratio (1: 1 w/w) to obtain a film-forming solution, into which the ZnO NPs and dragon fruit waste extract were incorporated. The resulting solution was cast into films, which were characterized using various analytical techniques. Mechanical properties, water solubility, and thermal stability of the films were also evaluated. The results demonstrated that the incorporation of green ZnO NPs and dragon fruit waste extract enhanced the mechanical strength and thermal stability of the films while reducing water vapor permeability. Moreover, the films exhibited biocidal and excellent 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging properties, indicating their use in the food packaging sector. The production of these films offers a practical approach to produce bioactive food packaging materials. The use of plant extract and waste material as reducing agents can reduce the overall cost of production while providing added benefits, such as antioxidant and antibacterial properties.

Characterization of Chitosan Films Modified Using Caffeic Acid and a Neutralization Process

In the context of the growing interest in biopolymer-based materials for various applications, this study aimed to enhance the properties of chitosan (CS, a derivative of chitin) films by incorporating caffeic acid, a polyphenol compound known for its multiple health benefits. The objective was to improve the mechanical parameters of the resulting films, including surface roughness and elasticity. CS was combined with caffeic acid and then underwent a neutralization process. The modified films exhibited potential for use in soft tissue engineering, where increased elasticity and surface roughness are desirable characteristics. The main methods employed to evaluate the structure and properties of the films included mechanical analysis, infrared spectroscopy, scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, contact angle measurement, and swelling behavior. The study's main findings revealed significant alterations in the mechanical properties and surface morphology of the films. The main conclusions drawn from the study suggest that interactions between caffeic acid and CS hold promise for the development of advanced biomaterials in medicine, tissue engineering, and cosmetic formulations. However, a deeper understanding of these interactions is necessary to optimize the material properties and unlock their full potential.

Three-dimension chitosan hydrogel loading melanin composite nanoparticles for wound healing by anti-bacteria, immune activation and macrophage autophagy promotion

Application of Combined photodynamic therapy (PDT) and photothermal therapy (PTT) has become one of the most promising strategy to replace antibiotics and avoid the epidemic of drug-resistant strains during wound healing. However, high amount of reactive oxygen species (ROS) and high temperature cause severe stress response to normal tissues, leading to potential risks of wound healing. Herein, a three-dimension chitosan hydrogel melanin-glycine-C60 nanoparticles (MGC NPs) were prepared to realized effective anti-bacterial activity, immune activation and macrophage autophagy promotion in three-dimensional wound space without triggering stress response. MGC NP is a composite polymer material composed of natural melanin polymer, oligopeptide and carbon-based material, which showed excellent biological safety. By regulating the peptide length between melanin and C60 and nanoparticle content, a high ROS/heat environment at the upper wound site and a low ROS/heat environment at the lower region adjacent to the wound tissue were established to obtain a three-dimension hydrogel with precise PDT and PTT efficiency in different regions. Highly effective PDT/PTT was used to kill microorganisms in upper region, thus providing a barrier to reduce microbial infection. Mild PDT/PTT in lower region promoted the polarization of M1 macrophage to M2 macrophage and activated autophagy of M2 macrophages, regulating the immune microenvironment and promoting wound repair. In conclusion, the novel three-dimensional PDT/PTT therapy based on natural macromolecules proposed in this study accelerates wound healing through dual pathways on the premise of avoiding wound stress response, which is of great significance for the development of clinical strategies for phototherapy.