Chitosan-gelatin composites and bi-layer films with potential antimicrobial activity

The Modification of In Situ SiOx Chitosan Coatings by ZnO/TiO2 NPs and Its Preservation Properties to Silver Carp Fish Balls

The composite chitosan coatings were prepared and characterized to evaluate their preservation properties for silver carp fish balls, and the microstructures and physicochemical properties of the coatings were improved by in situ nano silicon oxide (SiOx) and zinc oxide/titania (ZnO/TiO₂ ) nano-particles (NPs). In the chitosan coatings, when the chitosan combines with NPs by chemical bonds, the crystal lattice is slightly changed due to the modification of NPs. The chitosan coatings modified by NPs showed few cracks, among which sodium hexametaphosphate (SHMP) modified ZnO/TiO₂ /SiOx-chitosan (ZTS-CS) coating is proved to be the optimal one. The change of the freshness index and the texture of the fish balls are delayed by the coatings due to their gas permeability and antibacterial properties. The preservation properties of the chitosan coatings for Silver Carp fish balls are improved by in situ SiOx, and further improved by co-modification of ZnO/TiO₂ NPs. Furthermore, the surface modification of ZnO/TiO₂ NPs enhances the preservation properties of the chitosan coating. PRACTICAL APPLICATION: In our previous study, in situ SiOx was found to improve antibacterial and preservation properties of chitosan coating, leading to extending shelf time of Sciaenops ocellatus. In order to further improve properties of chitosan coatings, we added nontoxic edible nano materials to the in situ SiOx chitosan coatings. In situ SiOx modified by ZnO/TiO₂ NPs were synthesized, measured, and characterized in this study, and were applied for the preservation of silver carp fish balls. It could serve as a potential preservation material due to the increasing mechanical preservation properties. Through the results, the ZnO/TiO₂ /SiOx-chitosan (ZTS-CS) coatings have potential as application in the food industry to guarantee food quality and extend shelf life of products.

Characterization of hydroxyapatite-containing alginate-gelatin composite films as a potential wound dressing

In this study, hydroxyapatite (HA)-containing alginate-gelatin films were prepared by solution casting method by blending alginate (A) and gelatin (G) solutions, followed by crosslinking with calcium chloride. HA (1, 2, 5, 10, 20% w/w) was added to film solutions prepared at different ratios (A:G = 40:60, 50:50, and 60:40) and the swelling and degradation behavior, mechanical, antimicrobial and thermal properties, and morphologies of the obtained films were examined. The release of tetracycline hydrochloride (TH), selected as a model drug, from the prepared films was studied. It was observed that the swelling ratio and weight loss of the films decreased as the amounts of alginate and HA increased. Scanning electron microscopy analysis indicated that as the amount of HA in the films increased, the film surface becomes rougher. The mechanical properties of the films were affected by the amount of HA and the A:G ratio. Incorporation of HA increased the thermal stability of films. The amount of TH released from the films within 15 min decreased as the amounts of alginate and hydroxyapatite increased. It was found that films containing TH showed slightly higher antimicrobial activity against Staphylococcus aureus than Escherichia coli.

Processing of Superfine Grinding Corn Straw Fiber-Reinforced Starch Film and the Enhancement on Its Mechanical Properties

In this study, corn straw (CS) was reduced in size using the superfine grinding process to generate powders with particles of varying sizes (9~16 μm). The lignin, hemicellulose, and cellulose content; particle size distribution; and scanning electron microscopy (SEM) of the CS samples were analyzed. Superfine CS, of varying particle sizes, was added to the starch-based films (SF) in various amounts. The resulting corn straw starch-based films (CS/SFs) appeared to have significantly different properties, compared to the original starch-based film (SF, p < 0.05). The power law model and Burger's model were used to investigate the dynamic mechanical analysis, which indicated that the mechanical properties of CS/SF performed better than that of SF, especially CS/SFs at 0.5⁻1.5 h ball milling and CS/SFs at a 15% addition amount. The power law model and Burger's model also presented a strong correlation with the experimental data (>0.90).

Collagen from Cartilaginous Fish By-Products for a Potential Application in Bioactive Film Composite

The acid solubilised collagen (ASC) and pepsin solubilised collagen (PSC) were extracted from the by-products (skin) of a cartilaginous fish (Mustelus mustelus). The ASC and PSC yields were 23.07% and 35.27% dry weight, respectively and were identified as collagen Type I with the presence of α, β and γ chains. As revealed by the Fourier Transform Infrared (FTIR) spectra analysis, pepsin did not alter the PSC triple helix structure. Based on the various type of collagen yield, only PSC was used in combination with chitosan to produce a composite film. Such film had lower tensile strength but higher elongation at break when compared to chitosan film; and lower water solubility and lightness when compared to collagen film. Equally, FTIR spectra analysis of film composite showed the occurrence of collagen-chitosan interaction resulting in a modification of the secondary structure of collagen. Collagen-chitosan-based biofilm showed a potential UV barrier properties and antioxidant activity, which might be used as green bioactive films to preserve nutraceutical products.

Effect of ultrasound treatment on the properties of nano-emulsion films obtained from hazelnut meal protein and clove essential oil

Hazelnut meal protein (4% (w/v)) and clove essential oil (CEO) (3% (v/v)) were homogenized with ultrasound (US) at different times (2, 4 and 6 min) and amplitudes (50, 75 and 100%) to obtain nano-emulsion films. Film forming nano-emulsions (FFNs) were analyzed for average particle size (D_z) and zeta potential, and edible film characterization were evaluated depending on US treatment, as well as antibacterial and antioxidant activities. D_z values and zeta potential of FFNs decreased with increasing acoustic energy delivered to nano-emulsion system. Thickness and water solubility of films significantly decreased with increasing US treatment. Films became more transparent depending on US treatment probably due to particle size reduction. Tensile strength (TS) of films significantly increased with US treatment, while elongation at break (EAB) slightly increased. Microstructure of films became more homogeneous after US treatment and caused to lower water vapor permeability. Enrichment with CEO has given the films antibacterial activity against L. monocytogenes, B. subtilis, S. aureus, P. aeruginosa and E. coli, and antioxidant activity, and US application has improved these activities. US technology can be used to improve mechanical, barrier and antimicrobial properties of hazelnut meal protein based edible films enriched with CEO.

Film-forming ability of collagen hydrolysate extracted from leather solid wastes with chitosan

Discharges of huge quantities of leather solid wastes by leather industries and the increased use of synthetic packaging films have raised serious concerns on account of their environmental impacts. The paper focuses on the development and characterization of potential environmentally friendly composite films using collagen hydrolysate (CH) extracted from leather solid wastes and chitosan (C) to assess the feasibility of producing polymeric materials suitable for applications in packaging and wrapping purposes. Solid collagen-based protein hydrolysate was extracted from chromium-tanned leather wastes and analyzed to determine its chemical properties. With the goal of improving the physico-chemical performance of CH, three types of composite films (CH75/C25, CH50/C50, CH25/C75) were prepared with increasing concentrations of C, and some of their physical and functional properties were characterized. The results indicated that the addition of C caused increase (p < 0.05) in the thickness, tensile strength (TS), elasticity modulus (EM), and water vapor permeability (WVP), leading to stronger films as compared with CH film, but significantly (p < 0.05) decreased the elongation at break (EAB) and solubility of films (p < 0.05). The light barrier measurements present low values of transparency at 600 nm of the CH/C films, indicating that the films are very transparent and they have excellent barrier properties against UV light. The structural properties investigated by FTIR and DSC showed total miscibility between both polymers. Scanning electron micrographs revealed that CH/C composite films showed a compact homogeneous structure. These results demonstrate the potential application of CH/C composite films in packaging industry.

Physico-mechanical and structural properties of eggshell membrane gelatin- chitosan blend edible films

This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (p<0.05), but resulted in no significant change in tensile strength (TS) using 75G:25Ch, 50G:50Ch mixtures in comparison with gelatin-based film. The water solubility and water vapor permeability of the 50G:50Ch film decreased significantly compared to plain films (100G:0Ch and 0G:100Ch) and other composite films (p<0.05). Fourier transform infrared spectroscopy evaluation of structural properties showed that both polymers are totally miscible. Scanning electron microscopy was used to study the morphology of the composite films; it revealed a homogenous and compact structure in 75G:25Ch and 50G:50 Ch. Also, the chemical interactions introduced by the addition of chitosan to eggshell membrane gelatin as new resources could improve the films' functional properties.

Citrus essential oils: Extraction, authentication and application in food preservation

Citrus EOs is an economic, eco-friendly and natural alternatives to chemical preservatives and other synthetic antioxidants, such as sodium nitrites, nitrates or benzoates, commonly utilized in food preservation. Citrus based EOs is obtained mainly from the peels of citrus fruits which are largely discarded as wastes and cause environmental problems. The extraction of citrus oils from the waste peels not only saves environment but can be used in various applications including food preservation. The present article presents elaborated viewpoints on the nature and chemical composition of different EOs present in main citrus varieties widely grown across the globe; extraction, characterization and authentication techniques/methods of the citrus EOs; and reviews the recent advances in the application of citrus EOs for the preservation of fruits, vegetables, meat, fish and processed food stuffs. The probable reaction mechanism of the EOs based thin films formation with biodegradable polymers is presented. Other formulation, viz., EOs microencapsulation incorporating biodegradable polymers, nanoemulsion coatings, spray applications and antibacterial action mechanism of the active compounds present in the EOs have been elaborated. Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. Shift towards greener technologies indicate optimistic future towards safer utilization of citrus based EOs in food preservation.

Biocompatible Polyelectrolyte Complex Nanoparticles from Lactoferrin and Pectin as Potential Vehicles for Antioxidative Curcumin

Polyelectrolyte complex nanoparticles (PEC NPs) were fabricated via electrostatic interactions between positively charged heat-denatured lactoferrin (LF) particles and negatively charged pectin. The obtained PEC NPs were then utilized as curcumin carriers. PEC NPs were prepared by mixing 1.0 mg/mL solutions of heat-denatured LF and pectin at a mass ratio of 1:1 (w/w) in the absence of NaCl at pH 4.50. PEC NPs that were prepared under optimized conditions were spherical in shape with a particle size of ∼208 nm and zeta potential of ∼-32 mV. Hydrophobic curcumin was successfully encapsulated into LF/pectin PEC NPs with high encapsulation efficiency (∼85.3%) and loading content (∼13.4%). The in vitro controlled release and prominent antioxidant activities of curcumin from LF/pectin PEC NPs were observed. The present work provides a facile and fast method to synthesize nanoscale food-grade delivery systems for the improved water solubility, controlled release, and antioxidant activity of hydrophobic curcumin.

Molecular interactions in gelatin/chitosan composite films

Gelatin and chitosan were mixed at different mass ratios in solution forms, and the rheological properties of these film-forming solutions, upon cooling, were studied. The results indicate that the significant interactions between gelatin and chitosan promote the formation of multiple complexes, reflected by an increase in the storage modulus of gelatin solution. Furthermore, these molecular interactions hinder the formation of gelatin networks, consequently decreasing the storage modulus of polymer gels. Both hydrogen bonds and electrostatic interactions are formed between gelatin and chitosan, as evidenced by the shift of the amide-II bands of polymers. X-ray patterns of composite films indicate that the contents of triple helices decrease with increasing chitosan content. Only one glass transition temperature (T_g) was observed in composite films with different composition ratios, and it decreases gradually with an increase in chitosan proportion, indicating that gelatin and chitosan have good miscibility and form a wide range of blends.

Silver Nanoparticles Synthesized Using Mint Extract and their Application in Chitosan/Gelatin Composite Packaging Film

The present study reports synthesis of silver nanoparticles (AgNPs) using mint extract (ME) in the presence of polyvinyl alcohol (PVA) as capping material. PVA, ME and silver nitrate at concentration of 1%, 0.01% and 0.02%, respectively were found to be optimum for the synthesis of nanoparticles. The formation of AgNPs was confirmed by measuring surface plasmon resonance (SPR) peak. The intensity of SPR peak remained unaltered thus suggesting stability of colloid without aggregation during storage. The nanoparticles inhibited the growth of food borne bacteria namely Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus. The incorporation of these nanoparticles in chitosan and gelatin blend resulted in homogenous films. Mechanical properties and water vapor transmission rate of chitosan-gelatin films improved due to addition of AgNPs, whereas optical (opacity and UV light transmittance) and oxygen permeability properties remained unchanged. These films had the ability to inhibit growth of 5 log CFU of the above test organisms. These findings suggest that the AgNPs obtained by reduction of silver by ME can be effectively utilized to prepare antibacterial eco-friendly food packaging material.

Development of edible films obtained from submicron emulsions based on whey protein concentrate, oil/beeswax and brea gum

Edible films with whey protein concentrate (WPC) with a lipid component, sunflower oil (O) or beeswax (W), to enhance barrier to water vapor were obtained. Brea gum was used as emulsifier and also as matrix component. In order to achieve emulsion with small and homogeneous droplet size, an ultrasonicator equipment was used after obtaining a pre-emulsion using a blender. The films were made by casting. Effects of lipid fraction on droplet size, zeta potential, mechanical properties, water vapor permeability (WVP), solubility, and optical properties were determined. The droplet size of emulsions with BG decreased when decreasing the lipid content in the formulation. The zeta potential was negative for all the formulations, since the pH was close to 6 for all of them and pI of BG is close to 2.5, and pI of ß-lactoglobulin and α-lactalbumin (main proteins in WPC) are 5.2 and 4.1, respectively. Increasing W or SO content in blended films reduced the tensile strength and puncture resistance significantly. BG and WPC films without lipid presented better mechanical properties. The presence of lipids decreased the WVP, as expected, and those films having BG improved this property. BG films were slightly amber as a result of the natural color of the gum. BG has shown to be a good polysaccharide for emulsifying the lipid fraction and improving the homogeneity and mechanical properties of the films with WPC and beeswax or oil.

Formulation, in vitro evaluation and kinetic analysis of chitosan-gelatin bilayer muco-adhesive buccal patches of insulin nanoparticles

The present study was performed to optimise the formulation of a muco-adhesive buccal patch for insulin nanoparticles (NPs) delivery. Insulin NPs were synthesised by an ionic gelation technique using N-di methyl ethyl chitosan cysteine (DMEC-Cys) as permeation enhancer biopolymer, tripolyphosphate (TPP) and insulin. Buccal patches were developed by solvent-casting technique using chitosan and gelatine as muco-adhesive polymers. Optimised patches were embedded with 3 mg of insulin-loaded NPs with a homogeneous distribution of NPs in the muco-adhesive matrix, which displayed adequate physico-mechanical properties. The drug release characteristics, release mechanism and kinetics were investigated. Data fitting to Peppas equation with a correlation coefficient indicated that the mechanism of drug release followed an anomalous transport that means drug release was afforded through drug diffusion along with polymer erosion. In vitro drug release, release kinetics, physical and mechanical studies for all patch formulations reflected the ideal characteristics of this buccal patch for the delivery of insulin NPs.

Chitosan and gelatin based biodegradable packaging films with UV-light protection

Biopolymers are polymers obtained from biological origins and used for various biological and industrial applications. A biopolymer should be non-toxic, non-antigenic, non-irritant, non-carcinogenic, sterilisable and adequately available for their widespread applications. In this study, chitosan (CS) and gelatin (GL) based films were prepared to be used as biodegradable packaging films. CS was blended with GL to improve various physicochemical properties. The blended CSGL films were crosslinked with boric acid (BA) to improve various properties viz. light barrier properties, Water Vapour Permeability (WVP), moisture content (%), Total Solubility Matter (TSM), most important to improve the strength. The studies of transparency, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and optical microscopy confirms that the synthesized films were found to be transparent and homogenous indicating good compatibility among different components. The synthesized CS and GL based films showed UV-light barrier properties as supported by data. The tensile strength of films increases, decreases water solubility, moisture content (%) and WVP on crosslinking. In order to make the crosslinked films more flexible, Polyethylene glycol was used as plasticizer, making the films more flexible and transparent. This study indicates that these biodegradable CS and GL based films are potent to be used as packing films.