Fabrication and characterization of exfoliated chitosan–gelatin–montmorillonite nanocomposite nanofibers

Polymeric nanofibers as one of the most known nanotechnology products have huge potential applications in many fields due to their high aspect ratio and porosity, being capable of formation of three-dimensional structures and having great mechanical and biological properties. Chitosan is a natural abundant polymer which has attracted huge interests in biomedical and biological industries due to its biocompatible, biodegradable, and non-toxicity properties. However, electrospinning of chitosan is found to be a great challenge, blending it with other polymers such as gelatin was explored as means to improve the morphological deficiencies of chitosan nanofibers and facilitate its electrospinnability. On the other hand, montmorillonite (MMT) has been attracted great attention due to its remarkable improvement in properties of polymeric composites nanofibers. The main objective of this work was on effect of concretion of gelatin–chitosan blends and MMT on morphology of resulted nanocomposite nanofibers. The x-ray diffraction data demonstrated the exfoliation of MMT layers. The morphology of electrospun chiosan–gelatin–MMT composite nanofibers was characterized using scanning electron microscope (SEM). The miscibility of blend was determined using SEM and Fourier transform infrared spectrometer/attenuated total reflectance.     

Quinoa protein–chitosan–sunflower oil edible film: Mechanical,barrier and structural properties

Quinoa protein extracts (Q) were prepared and alkalised at pH 8 and 12 (Q-8 and Q-12). Qs were mixed with chitosan (CH) to form Q/CH mixtures. The optimal proportion of the mixtures was determined by the formation of coacervates. All the films were obtained by solution casting. From the optimal Q/CH mixture and the addition of three different concentrations of sunflower oil (SO) 2.9, 3.8 and 4.7 g/100 mL, and the optimal proportion of SO g/100 mL was selected based on the mechanical and barrier properties of the films. The CH, Q/CH and Q/CH/SO optimal blend films were characterised by FTIR, X-ray diffraction, and SEM. The physicochemical properties of the films were also evaluated. The 0.1 Q-8/CH blend was selected due to its high degree of interaction between the quinoa proteins and CH. The optimum concentration of SO used in the Q-8/CH/SO film was 2.9 g/100 mL. The addition of SO to the film improved the water-vapour permeability (WVP) as a result of hydrophobic interactions and the presence of clusters of hydrophobic masses on the surfaces of these films but reduced the film’s tensile strength and oxygen permeability due to the formation of micropores and microfractures detected by SEM.     

Preparation and characterization of glycerol plasticized (high-amylose) starch–chitosan films

The chitosan–starch (high amylose) blend film (1;1), via microfluidization, was prepared by casting with different glycerol concentration (0%, 2.5%, 5% and 10%). The films were characterized for their mechanical, thermal and morphological properties. The addition of glycerol at 5% (w/w) and higher concentrations resulted in decrease in tensile strength, increase in elongation at break due to plasticization. The well-known antiplasticization was observed in the polymer films with 2.5% of glycerol. The addition of glycerol promoted the interactions among chitosan, starch and glycerol through hydrogen bonding as reflected on the shifting of main peaks of the glycerol-free film to higher wavenumbers as shown by FTIR spectra. The decrease in intensity of glycerol-related peaks in starch–chitosan–glycerol films in both ¹H NMR and ¹³C NMR spectra proved the strong interactions (decrease in glycerol mobility) occurring among starch, chitosan and glycerol in glycerol-plasticized films.     

Physical and antimicrobial properties of chitosan–tea tree essential oil composite films

Antimicrobial films were prepared by incorporating different concentrations of tea tree essential oil (TTO) into chitosan (CH) films. Film-forming dispersions (FFD) were characterized in terms of rheological properties, particle size distribution and ζ-potential. In order to study the impact of the incorporation of TTO into the CH matrix, the water vapour permeability (WVP), mechanical and optical properties of the dry films were evaluated. The properties of the films were related with their microstructure, which was observed by SEM. Furthermore, the antimicrobial effectiveness of CH–TTO composite films against Listeria monocytogenes and Penicillium italicum was studied.     

Characterization of chitosan–oleic acid composite films

Edible films based on high molecular weight chitosan (CH) and different concentrations of oleic acid (OA) were prepared. Film-forming dispersions (FFD) were characterized in terms of rheological properties, surface tension, particle size distribution and ζ-potential. In order to study the impact of the incorporation of OA into the CH matrix, the water sorption isotherms, water vapour permeability (WVP), mechanical properties, and optical properties of the dry films were evaluated. Results showed that the increase in OA promoted changes in the size and surface charge of the FFD particles, which had an impact on the rheological properties of the FFD. As regards the film properties, the higher the OA content, the lower the WVP and the moisture sorption capacity. In general, the addition of OA into the CH matrix leads to a significant increase in gloss and translucency and a decrease in the tensile strength, elongation at break and elastic modulus of the composite films. The mechanical and optical properties of the films were related with their microstructure, which was observed by SEM.     

Physico-chemical,mechanical and electrical performance of bael fruit gum–chitosan IPN films

The gum obtained from unripe fruits of Aegle marmelos was co-processed with chitosan to improve the film forming property of the former. The results of FTIR and differential thermal analysis of films revealed maximum interaction between –COO⁻ groups of gum and –NH₃⁺ of chitosan when they were present in equal proportion in the film. These films exhibited almost negligible zeta potential and the surface remained smooth after exposure to both acidic and alkaline pH as observed under scanning electron microscope. The contact angle and swelling index of this film in both acidic and alkaline buffers were observed to be lowest as compared to other films prepared with different ratios of gum and chitosan. The work of adhesion and spreading coefficient for this film was observed to be lowest. These results could be attributed to optimum interaction between –COO⁻ groups of gum and –NH₃⁺ groups of chitosan. These results indicated the ability of this film for use in modifying drug release and processed food items.     

The antimicrobial,mechanical, physical and structural properties of chitosan–gallic acid films

Chitosan films incorporated with various concentrations of gallic acid were prepared and investigated for antimicrobial, mechanical, physical and structural properties. Four bacterial strains that commonly contaminate food products were chosen as target bacteria to evaluate the antimicrobial activity of the prepared gallic acid–chitosan films. The incorporation of gallic acid significantly increased the antimicrobial activities of the films against Escherichia coli, Salmonella typhimurium, Listeria innocua and Bacillus subtilis. Chitosan films incorporated with 1.5 g/100 g gallic acid showed the strongest antimicrobial activity. It was also found that tensile strength (TS) of chitosan film was significantly increased when incorporating 0.5 g/100 g gallic acid. Inclusion of 0.5 g/100 g gallic acid also significantly decreased water vapor permeability (WVP) and oxygen permeability (OP). Microstructure of the films was investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) and it was found that gallic acid was dispersed homogenously into the chitosan matrix.     

Characterization of quinoa protein–chitosan blend edible films

Quinoa protein/chitosan films were obtained by solution casting of blends of quinoa protein extract (PE) and chitosan (CH). Films from a PE/CH blend were characterized by FTIR, X-ray diffraction, thermal analysis, and SEM. The tensile mechanical, barrier, and sorption properties of the films were also evaluated. The blend of PE with CH yielded mechanically resistant films without the use of a plasticizer. The film had large elongation at break, and its water barrier properties showed that they were more hydrophilic than CH film. The thickness and water-vapor permeability of PE/CH (v/v) 1/1 blend film increased significantly compared to pure CH films. CH films are translucent in appearance and yellowish in blend with PE. By blending anionic PE with cationic CH an interaction between biopolymers was established with different physicochemical properties from those of pure CH. Drying and sorption properties show significant differences between PE/CH blend film and CH film. The structural properties determined by XRD, FTIR and TGA showed a clear interaction between quinoa proteins and CH, forming a new material with enhanced mechanical properties.     

Active chitosan–polyvinyl alcohol films with natural extracts

Active films were prepared from chitosan (Ch) and polyvinyl alcohol (PVA) containing aqueous mint extract (ME)/pomegranate peel extract (PE). The effect of these extracts on the physical, mechanical, antimicrobial and antioxidant properties of the films were studied. Increased protection against UV light was observed in the films containing the extracts. Addition of ME/PE improved the tensile strength of the films without affecting their puncture strength. Ch–PVA films incorporated with PE had the highest tensile strength (41.07 ± 0.88 MPa). Permeability characteristics of the films were not altered due to addition of extracts. ME/PE conferred antioxidant properties to Ch–PVA films as determined by DPPH radical scavenging activity. The films also exhibited antibacterial activity against Staphylococcus aureus and Bacillus cereus. PE containing films totally inhibited the growth of B. cereus and reduced the number of S. aureus by 2 log cycles. These results suggest that Ch–PVA film containing ME/PE can be used for development of active food packaging materials.     

Characterization and antibacterial property of Kapok fibers treated with chitosan/AgCl–TiO2 colloid

The aim of this research is to investigate the antibacterial activity of Kapok fibers modified with AgCl/TiO₂ and Chitosan colloid. A very simple, single-step (pad-dry-cure) method was used for the application of AgCl/TiO₂ and Chitosan colloid on kapok fibers, the chemicals used are easily available. Different blend ratios of chitosan and AgCl/TiO₂ colloid were applied to the bleached kapok fibers and antibacterial properties were assayed against gram positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The treated kapok fibers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It was observed that the bacterial growth was significantly reduced in the samples which had a higher concentration of chitosan and AgCl/TiO₂ colloid. However, a significant reduction in bacterial growth with the use of this colloid was observed.     

Comparison of chitosan–gelatin composite and bilayer coating and film effect on the quality of refrigerated rainbow trout

The effect of chitosan–gelatin coating and film on the rancidity development in rainbow trout (Oncorhynchus mykiss) fillets during refrigerated storage (4 ± 1 °C) was examined over a period of 16 days. Composite and bilayer coated and film wrapped fish samples were analysed periodically for microbiological (total viable count, psychrotrophic count) and chemical (TVB-N, POV, TBARS, FFA) characteristics. The results indicated that chitosan–gelatin coating and film retained their good quality characteristics and extend the shelf life of fish samples during refrigerated storage .The coating was better than the film in reducing lipid oxidation of fillets, but there was no significant difference between them in control of bacterial contamination.     

Effect of the incorporation of antioxidants on physicochemical and antioxidant properties of wheat starch–chitosan films

Blend edible films were prepared from wheat starch (WS) and chitosan (CH) with glycerol as plasticizer. Four active ingredients (antioxidants) were added, namely basil essential oil, thyme essential oil, citric acid and α-tocopherol. The starch:antioxidant mass ratio was 1:0.1. Prior to characterisation, the films were conditioned at 25 °C–53%RH as to their structural, mechanical, optical and barrier properties. The antioxidant capacity of the active ingredients was determined by means of a spectrophotometric method. The incorporation of antioxidants led to a heterogeneous film microstructure, mainly in those containing α-tocopherol, which affected the surface roughness. Yellowness was induced in films when α-tocopherol was added and no notable colour changes were observed in the other cases, although all the antioxidants increased the transparency of the films. Despite of the fact that the mechanical properties were barely affected by the incorporation of antioxidants, citric acid promoted an increase in the elastic modulus but a decrease in film stretchability. The water vapour barrier properties of the films were only slightly improved when citric acid and α-tocopherol were added, whereas the oxygen barrier properties were significantly improved in all cases. The greatest antioxidant capacity of the films was reported for films containing α-tocopherol, which exhibited the highest antioxidant power.     

Effect of complexation conditions on xanthan–chitosan polyelectrolyte complex gels

Polyelectrolyte hydrogels formed by xanthan gum and chitosan can be used for encapsulation and controlled release of food ingredients, cells, enzymes, and therapeutic agents. In this study, xanthan–chitosan microcapsules were formed by complex coacervation. The effects of initial polymer concentration and chitosan solution pH on the crosslinking density of xanthan–chitosan network were investigated by swelling studies and modulated differential scanning calorimetry (MDSC) analysis. The crosslinking density was found to be less dependent on chitosan solution concentration than xanthan solution concentration and chitosan pH. The capsules were completely crosslinked at all conditions studied when initial xanthan solution concentration was 1.5% (w/v). The changes in the conformation of chitosan chains as chitosan pH approaches 6.2 were found to be important in achieving capsule network structures with different crosslinking densities. These findings indicate that the parameters studied cannot be viewed as independent parameters, as their effects on the degree of swelling are interdependent.     

Effects of gelatin origin,bovine-hide and tuna-skin,on the properties of compound gelatin–chitosan films

With the purpose to improve the physico-chemical performance of plain gelatin and chitosan films, compound gelatin–chitosan films were prepared. The effect of the gelatin origin (commercial bovine-hide gelatin and laboratory-made tuna-skin gelatin) on the physico-chemical properties of films was studied. The dynamic viscoelastic properties (elastic modulus G′, viscous modulus, G″ and phase angle) of the film-forming solutions upon cooling and subsequent heating revealed that the interactions between gelatin and chitosan were stronger in the blends made with tuna-skin gelatin than in the blends made with bovine-hide gelatin. As a result, the fish gelatin–chitosan films were more water resistant (∼18% water solubility for tuna vs 30% for bovine) and more deformable (∼68% breaking deformation for tuna vs 11% for bovine) than the bovine gelatin–chitosan films. The breaking strength of gelatin–chitosan films, whatever the gelatin origin, was higher than that of plain gelatin films. Bovine gelatin–chitosan films showed a significant lower water vapour permeability (WVP) than the corresponding plain films, whereas tuna gelatin–chitosan ones were only significantly less permeable than plain chitosan film. Complex gelatin–chitosan films behaved at room temperature as rubbery semicrystalline materials. In spite of gelatin–chitosan interactions, all the chitosan-containing films exhibited antimicrobial activity against Staphylococcus aureus, a relevant food poisoning. Mixing gelatin and chitosan may be a means to improve the physico-chemical performance of gelatin and chitosan plain films, especially when using fish gelatin, without altering the antimicrobial properties.     

Antioxidative properties of a chitosan–glucose Maillard reaction product and its effect on pork qualities during refrigerated storage

The objective of this study was to evaluate the antioxidative properties of a chitosan–glucose Maillard reaction product (CG-MRP), and its effect on pork qualities during refrigerated storage. Chitosan (1%), which was dissolved in acetic acid (1%) with 1.0%, 1.5%, or 2.0% glucose, pH adjusted to 6.0, autoclaved (121 °C, 15 min) and cooled, was prepared. The results showed that the 2,2-dipheny1-1-picrylhydrazy1 (DPPH) radical scavenging activities, ferrous ion chelating abilities, and reducing powers of various CG-MRP solutions were not significantly different. Pork loins soaked in the CG-MRP solutions or deionized water for 10 min and without dipping were stored at 4 °C for 7 days. Little influence was observed on the L∗, a∗, and b∗ colour values of the samples. Dipping in CG-MRP tended to retard the increases in volatile basic nitrogen (VBN) and thiobarbituric acid-reactive substances (TBARS) values, and resulted in lower microbial counts during storage. No detrimental influence on the sensory characteristics was found.     

Carboxymethyl chitosan–soy protein complex nanoparticles for the encapsulation and controlled release of vitamin D3

In this study, complex nanoparticles were developed from carboxymethyl chitosan (CMCS) and soy protein isolate (SPI) by a simple ionic gelation method. The effect of Ca²⁺ concentration, pH and CMCS/SPI mass ratio on the formation of nanoparticles was systematically investigated. Vitamin D₃ (VD), a hydrophobic micronutrient, was successfully incorporated into the polymeric complex, forming particles with sizes between 162 and 243 nm and zeta potentials ranging from −10 to −20 mV. In comparison with CMCS, the CMCS/SPI complex required a lower concentration of Ca²⁺, and it showed better particle forming capability over a broad range of pH. These features resulted in an increased loading efficiency to 6.06%. In addition, the complex nanoparticles achieved significantly higher encapsulation efficiency (up to 96.8%), possibly due to their compact structure and high capability of hydrogen bonding evidenced by Fourier transform infrared spectroscopy (FTIR). In contrast to the ones prepared with SPI, the complex nanoparticles exhibited a reduced (42.3% compared to 86.1%) release of VD in simulated gastric fluid and an increased (36.0% compared to 8.2%) release under simulated intestinal condition. These characteristics made the CMCS/SPI complex nanoparticles an attractive candidate for the encapsulation and controlled release of hydrophobic nutraceuticals and bioactives.     

Development and characterization of an edible chitosan–whey protein nano composite film for chestnut (Castanea mollissima Bl.) preservation

Chitosan (CHI) and whey protein are usually used to prepare edible films for food preservation. However, the composite film composed of the two components does not yield satisfactory properties for chestnut preservation. In this study, nano-cellulose and cinnamaldehyde (CMA) were added to CHI and whey protein, creating a new composite film with strong water retention, bacteriostatic, and mechanical properties. The water vapor permeability (WVP) of the film decreased by 21.61% with the addition of 0.5% (w/v) nano-cellulose, and 23.02% with the addition of 0.3% (w/v) CMA. Furthermore, water solubility (WS) decreased 22.05%, and the density of the film was significantly improved with the addition of 0.3% (w/v) CMA. The optimized formula of the film was CHI 2.5% (w/v), whey protein 3.0% (w/v), nano-cellulose 0.5% (w/v), CMA 0.3% (w/v), and pH 3.8, as determined by orthogonal testing L9(3⁴), with fuzzy comprehensive assessment, of WVP, WS, tensile strength, and elongation at break. The film clearly inhibited the growth of E. coli, S. aureus, and Chinese chestnut fungus, destroying the mycelial structure of the fungus. In addition, coating effectively reduced the weight loss, mildew rate, and calcification index during 16 days of storage of chestnuts at 25 °C.     

Concurrent phase separation and gelation in mixed oat β-glucans/sodium caseinate and oat β-glucans/pullulan aqueous dispersions

The phase separation behavior of mixed oat β-glucans/sodium caseinate and oat β-glucans/pullulan aqueous dispersions at 20 °C has been studied. The concentration of β-glucans required for induction of phase separation and the physical state of the separated phases, as revealed by visual observations and dynamic rheometry, depended on the molecular weight of β-glucans and the initial polymeric composition. For β-glucans with apparent molecular weights (M_w) 35 and 65 × 10³ the β-glucan concentration at which thermodynamic incompatibility occurred decreased from about 2–2.5% (w/w) at low concentrations (∼0.2%) of sodium caseinate or pullulan to about 1–1.5% (w/w) β-glucans at high levels (up to 7.5% w/w) of the second biopolymer; these bi-phasic systems consisted of an upper liquid phase and a lower gel-like phase. For β-glucans with M_w of 110 × 10³, a bi-phasic system with two liquid phases appeared above a certain β-glucan concentration, which decreased from approximately 4% to 1% (w/w) with increasing sodium caseinate levels in the range of 0.2–7.5% (w/w). With further increase in β-glucan concentration, the lower phase turned into a gel, and at even higher β-glucan concentrations, the polymer demixing process was ‘arrested’ by chain aggregation events, leading to a macroscopically single gel phase. Generally, the aggregation of β-glucans seemed to interfere with the phase separation phenomenon resulting in an increase of β-glucan concentration in the lower phase between 5% and 110% and only a slight increase of sodium caseinate or pullulan concentration in the upper phase (<10%), due to kinetic entrapment of the polymeric components into a highly viscous medium.     

Dyeing and kinetics of chitosan modified acrylic fabric with reaction dye北大核心

Chitosan modified acrylic fabric was dyed with reactive brilliant red X-3B. The dye uptake, fixing rate, K/S values and washing fastness were investigated in dyed process. The dyeing rate curve of chitosan modified acrylic fabric with reactive brilliant red X-3B was tested. The effects of different temperatures on dyeing kinetic parameters such as half-dyeing time, diffusion coefficient and dyeing rate constant were analyzed. The results showed that the dye uptake was 31.28%, the fixing rate was 28.60%, the K/S value was 3.931, and the washing fastness up to 3. The dyeing property of chitosan modified acrylic fabric with reactive brilliant red X-3B was good. And it reached dyeing equilibrium after 60 min dyeing time. The half-dyeing time of chitosan modified acrylic fabric dyed by reactive brilliant red X-3B was short and can be decreased with the increase of temperature. Besides, diffusion coefficient and dyeing rate constant can be gradually increasing with the increase of the dyeing temperature.     

Quality of eggs coated with oil–chitosan emulsion: Combined effects of emulsifier types,initial albumen quality,and storage

Effects of mineral oil:chitosan (MO:CH at 25:75) emulsions prepared with four different emulsifiers (2 water- and 2 oil-miscible) as coatings on the internal quality (weight loss, Haugh unit, yolk index, and albumen pH) of coated eggs were evaluated during 5 weeks at 25 ± 2 °C and 20 weeks at 4 ± 2 °C. Eggs with two initial albumen qualities [Haugh unit (HU): H = 87.8 and L = 70.9] were used. At 25 ± 2 °C, Haugh unit, yolk index, and albumen pH of all coated eggs decreased with increased storage time. Coated H- and L-eggs maintained an A-grade up to 4 weeks and 1 week, respectively. Weight loss of all coated eggs remained below 1.35% after 5 weeks of storage at 25 ± 2 °C. All coated eggs maintained an A-grade with less than 2.5% weight loss during 20 weeks of storage at 4 ± 2 °C. Emulsifier types marginally affected the internal quality of coated eggs regardless of storage temperatures.