Structural, Thermal, Physical, Mechanical, and Barrier Properties of Chitosan Films with the Addition of Xanthan Gum

A novel anthocyanin indicator film with rosmarinic acid copigmentation having enhanced stability and pH indicator ability for monitoring pork freshness

BACKGROUND

Anthocyanin-based pH-sensing films have been widely fabricated for potential application in monitoring food freshness. However, the color fading of anthocyanins limits their application for the food industry due to their low stability. In addition, the color sensitivity and pH indicator ability of anthocyanin-based films currently available are not satisfied and need to be improved.

RESULTS

Chitosan/xanthan gum (CX)-based colorimetric films with addition of purple cabbage anthocyanin (PAN) and different amounts of rosmarinic acid (RA) were fabricated. RA copigmentation in chitosan/xanthan gum-purple cabbage anthocyanin-rosmarinic acid (CX-P-RA) films significantly improved the stability and pH response sensitivity of PAN, and the combined copigmentation of RA and xanthan gum exhibited an additive effect. The addition of RA significantly improved the tensile strength and elongation at break, thermal stability, antioxidant and antibacterial activities of CX-P-RA films. Moreover, addition of RA enhanced the pH sensitivity and colorimetry of CX-P-RA films, which exhibited a good response to different pH values. CX-P-RA2 film was tested to monitor the freshness of pork. It showed visible color changes during the storage of pork. In addition, the ∆E of CX-P-RA2 film was highly correlated with changes in total volatile basic nitrogen in pork (R2  = 0.951).

CONCLUSION

These results indicated that CX-P-RA2 film can be used as a pH-sensing indicator with good stability and high sensitivity for real-time monitoring of pork freshness. © 2023 Society of Chemical Industry.

Chitosan/konjac glucomannan bilayer films: Physical, structural, and thermal properties

To overcome the limitations of chitosan (CS) and konjac glucomannan (KGM), the bilayer films of CS and KGM were prepared by layer-by-layer (LBL) casting method, and the effects of different mass ratios (i.e., C5: K0, C4:K1, C3:K2, C1:K1, C2:K3, C1:K4, and C0:K5) on the microstructures and physicochemical properties of bilayer films were examined to evaluate their applicability in food packaging. The results revealed that the bilayer films had uniform microstructures. When compared with pure films, the bilayer films displayed lower swelling degrees and water vapor permeability. However, the tensile tests revealed a reduction in the mechanical properties of the bilayer films, which was nonetheless superior to that of the pure KGM film. In addition, the intermolecular interactions between the CS and KGM layers were observed through FTIR and XRD analyses. Finally, TGA and DSC analyses demonstrated a decrease in the thermal stability of the bilayer films. Our cumulative results verified that CS-KGM bilayer films may be a promising material for use in food packaging and further properties of the bilayer films can be supplemented in the future through layer-by-layer modification and the addition of active ingredients.

Development of Eco-Friendly Biocomposite Films Based on Opuntia ficus-indica Cladodes Powder Blended with Gum Arabic and Xanthan Envisaging Food Packaging Applications

Currently, food packaging is facing a critical transition period and a major challenge: it must preserve the food products' quality and, at the same time, it must meet the current requirements of the circular economy and the fundamental principles of packaging materials eco-design. Our research presents the development of eco-friendly packaging films based on Opuntia ficus-indica cladodes (OFIC) as renewable resources. OFIC powder (OFICP)-agar, OFICP-agar-gum arabic (GA), and OFICP-agar-xanthan (XG) blend films were eco-friendlily prepared by a solution casting method. The films' properties were investigated by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), and differential scanning calorimeter (DSC). Water solubility and moisture content were also determined. Morphology, thickness, molecular interactions, miscibility, crystallinity, and thermal properties, were affected by adjusting the gums (GA and XG) content and glycerol in the blend films. Moisture content increased with increasing glycerol and XG content, and when 1.5 g of GA was added. Water solubility decreased when glycerol was added at 50% and increased with increasing GA and XG content. FTIR and XRD confirmed strong intermolecular interactions between the different blend film compounds, which were reflected in the shifting, appearance, and disappearance of FTIR bands and XRD peaks, indicating excellent miscibility. DSC results revealed a glass transition temperature (Tg) below room temperature for all prepared blend films, indicating that they are flexible and soft at room temperature. The results corroborated that the addition of glycerol at 30% and the GA to the OFICP increased the stability of the film, making it ideal for different food packaging applications.

Physical, Chemical, Barrier, and Antioxidant Properties of Pectin/Collagen Hydrogel-Based Films Enriched with Melissa officinalis

The essential oil extracted from Melissa officinalis (MOEO) exhibits a wide range of therapeutic properties, including antioxidant, antibacterial, and antifungal activities. The current research aimed to analyze the mechanical, barrier, chemical, and antioxidant properties of pectin and collagen-based films. Hydrogel-based films loaded with varying concentrations of MOEO (0.1%, 0.15%, and 0.2%) were prepared by solvent-casting method, and their physicochemical as well as antioxidant properties were examined. GC-MS analysis revealed the presence of major components in MOEO such as 2,6-octadienal, 3,7-dimethyl, citral, caryophyllene, geranyl acetate, caryophyllene oxide, citronellal, and linalool. Fourier transform infrared (FTIR) results revealed the interaction between components of the essential oil and polymer matrix. Scanning electron microscopy (SEM) revealed that films loaded with the highest concentration (0.2%) of MOEO showed more homogeneous structure with fewer particles, cracks, and pores as compared to control film sample. MOEO-incorporated films exhibited higher elongation at break (EAB) (30.24-36.29%) and thickness (0.068-0.073 mm); however, they displayed lower tensile strength (TS) (3.48-1.25 MPa) and transparency (87.30-82.80%). MOEO-loaded films demonstrated superior barrier properties against water vapors. According to the results, the incorporation of MOEO into pectin-collagen composite hydrogel-based films resulted in higher antioxidant properties, indicating that MOEO has the potential to be used in active food packaging material for potential applications.

Green Synthesis of Hydrogel-Based Adsorbent Material for the Effective Removal of Diclofenac Sodium from Wastewater

The removal of pharmaceutical contaminants from wastewater has gained considerable attention in recent years, particularly in the advancements of hydrogel-based adsorbents as a green solution for their ease of use, ease of modification, biodegradability, non-toxicity, environmental friendliness, and cost-effectiveness. This study focuses on the design of an efficient adsorbent hydrogel based on 1% chitosan, 40% polyethylene glycol 4000 (PEG4000), and 4% xanthan gum (referred to as CPX) for the removal of diclofenac sodium (DCF) from water. The interaction between positively charged chitosan and negatively charged xanthan gum and PEG4000 leads to strengthening of the hydrogel structure. The obtained CPX hydrogel, prepared by a green, simple, easy, low-cost, and ecological method, has a higher viscosity due to the three-dimensional polymer network and mechanical stability. The physical, chemical, rheological, and pharmacotechnical parameters of the synthesized hydrogel were determined. Swelling analysis demonstrated that the new synthetized hydrogel is not pH-dependent. The obtained adsorbent hydrogel reached the adsorption capacity (172.41 mg/g) at the highest adsorbent amount (200 mg) after 350 min. In addition, the adsorption kinetics were calculated using a pseudo first-order model and Langmuir and Freundlich isotherm parameters. The results demonstrate that CPX hydrogel can be used as an efficient option to remove DCF as a pharmaceutical contaminant from wastewater.

Combined Effect of Drying Temperature and Varied Gelatin Concentration on Physicochemical and Antioxidant Properties of Ginger Oil Incorporated Chitosan Based Edible Films

In the present work, ginger essential oil (GEO) loaded chitosan (CS) based films incorporated with varying concentrations of gelatin (GE) were fabricated and dried at different conditions (25 °C and 45 °C). The physio-chemical, mechanical and antioxidant potential of the films were determined. Films dried at 45 °C showed better physical attributes and less thickness, swelling degree (SD), moisture content, water vapor permeability (WVP), more transparency, and better mechanical characteristics. Fourier transform infrared spectroscopy (FTIR) revealed the chemical composition and interaction between the functional groups of the film components. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) findings revealed that samples dried at 45 °C had more crystalline structure, were thermally stable, and smoother. Antioxidant results showed that films dried at low temperature showed comparatively more (p < 0.0001) antioxidant activity. Additionally, an increase in gelatin concentration improved the tensile strength and swelling factor (p < 0.05), however, had no significant impact on other parameters. The overall results suggested better characteristics of GEO-loaded CS-GE based edible films when dried at 45 °C.

Robust Antibacterial Activity of Xanthan-Gum-Stabilized and Patterned CeO2-x-TiO2 Antifog Films

Increased occurrence of antimicrobial resistance leads to a huge burden on patients, the healthcare system, and society worldwide. Developing antimicrobial materials through doping rare-earth elements is a new strategy to overcome this challenge. To this end, we design antibacterial films containing CeO_2-x-TiO₂, xanthan gum, poly(acrylic acid), and hyaluronic acid. CeO_2-x-TiO₂ inks are additionally integrated into a hexagonal grid for prominent transparency. Such design yields not only an antibacterial efficacy of ∼100% toward Staphylococcus aureus and Escherichia coli but also excellent antifog performance for 72 h in a 100% humidity atmosphere. Moreover, FluidFM is employed to understand the interaction in-depth between bacteria and materials. We further reveal that reactive oxygen species (ROS) are crucial for the bactericidal activity of E. coli through fluorescent spectroscopic analysis and SEM imaging. We meanwhile confirm that Ce³⁺ ions are involved in the stripping phosphate groups, damaging the cell membrane of S. aureus. Therefore, the hexagonal mesh and xanthan-gum cross-linking chains act as a reservoir for ROS and Ce³⁺ ions, realizing a long-lasting antibacterial function. We hence develop an antibacterial and antifog dual-functional material that has the potential for a broad application in display devices, medical devices, food packaging, and wearable electronics.

Optimization of Antibacterial, Physical and Mechanical Properties of Novel Chitosan/Olibanum Gum Film for Food Packaging Application

Chitosan-based films are promising active biodegradable materials with the ability to be enhanced by different materials, including gums. This study aims to optimize the physical (transmittance, water vapor permeability and water solubility), mechanical (tensile strength and elongation at break) and antibacterial (against Staphylococcus aureus and Salmonella Typhimurium) properties of newly fabricated chitosan/olibanum gum (CH/OG) films as a function of different levels of CH (0.5, 0.75, 1, 1.25 and 1.5% w/v) and OG (0.125, 0.25, 0.375, 0.5 and 0.625% w/v), using response surface methodology (RSM). Moreover, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were used to better characterize the fabricated films. RSM analysis results showed the significant fitting of all dependent variable responses to the quadratic polynomial model. To attain the desirable physical, mechanical and antibacterial responses, the optimal concentrations were 1.31% (w/v) CH and 0.3% (w/v) OG. The encouraging antibacterial, physical and mechanical properties of the developed composites support the application of chitosan/gum blends in active food packaging, particularly for perishable foodstuffs, such as meat and horticultural products.

Investigation of 3D-printed chitosan-xanthan gum patches

In this study, using a new polymer combination of Chitosan(CH)/Xanthan Gum(XG) has been exhibited for wound dressing implementation by the 3D-Printing method, which was fabricated due to its biocompatible, biodegradable, improved mechanical strength, low degradation rate, and hydrophilic nature to develop cell-mimicking, cell adhesion, proliferation, and differentiation. Different concentrations of XG were added to the CH solution as 0.25, 0.50, 0.75, 1, and 2 wt% respectively in the formic acid/distilled water (1.5:8.5) solution and rheologically characterized to evaluate their printability. The results demonstrated that high mechanical strength, hydrophilic properties, and slow degradation rate were observed with the presence and increment of XG concentration within the 3D-Printed patches. Moreover, in vitro cell culture research was conducted by seeding NIH 3T3 fibroblast cells on the patches, proving the cell proliferation rate, viability, and adhesion. Finally, 1% XG and 4% CH containing 3D-Printed patches were great potential for wound dressing applications.

Development of hydroxypropyl methylcellulose film with xanthan gum and its application as an excellent food packaging bio-material in enhancing the shelf life of banana

A novel film composed of xanthan gum (XG) and hydroxypropyl methylcellulose (HPMC) was prepared (XH). The films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The light transmittance, mechanical properties and water vapor transmission rate (WVTR) indicated the good compatibility between XG and HPMC with hydrogen-bond interaction and XG had a significant effect on the chemical structure, crystalline texture and microstructure of the XH composite film. The best XH sample with optimum XG concentration of 2 g/L was used as food packaging via coating onto banana, whereby the weight loss rate on banana was able to decreased from 25 ± 3% (without XH coating) to 16 ± 4% (with XH coating). Consequently, the release of flavor substances was also decreased. Banana shelf life has qualitatively improved with XH composite film for food preservation and affirmed the uses in food packaging applications.

Effect of Complexation Conditions on Microcapsulation of Lactobacillus Casei L61 in Gellan Gum–Chitosan Gels

Probiotics have many benefits for human intestinal health. However, Probiotics have poor tolerance to gastric acid and bile salts of the stomach. Microencapsulation could confer protection to probiotic against harsh environments effectively. In this experiment, Lactobacillus casei L61 was embedded by extrusion with gellan gum and chitosan as wall material. The viable cells and encapsulation yield of microcapsules were used as the indexes, the optimum values of each factor were determined by a single factor experiment. Chitosan concentration 0.50%, chitosan pH 4.5, gellan gum concentration 1.50%, the volume ratio of bacterial suspension to gellan gum is 1:6, the volume ratio of bacterial gum to chitosan is 1:4, the stirring time is 40min.

In Situ Self-Organizing Materials for Local Stress-Responsive Reconstruction of Skin Interstitium

Remodeling of the fibrous network in the skin interstitium is a crucial step in the process of skin wound healing. In the present study, a hierarchically structured xanthan gum-chitosan (XG-CS) composite hydrogel is developed as a skin wound healing material that responds to stress at wound sites by in situ self-organizing and self-repairing the interstitial fibrous network. The composite gel adheres tightly to the injured fibers forming an intact interstitial pathway, and thereby promotes the physiological function of fibroblasts. A software-based quantitative assessment is performed to evaluate the stress state at wound sites, which confirms that the composite gel adapted in vivo to wound stress and ultimately promotes fast wound healing. The results highlight the importance of interstitial reconstruction in tissue recovery, and will inspire novel strategies in regenerative medicine.

Preparation, and physicochemical and biological evaluation of chitosan-Arthrospira platensis polysaccharide active films for food packaging

Active films from chitosan incorporated with Arthrospira platensis polysaccharide (APP) of various ratios (0.0%, 0.5%, and 1.0%, w/v) were developed by solution casting. The effect of APP on the structural, physicochemical, mechanical, antimicrobial, and antioxidant properties of the chitosan-APP films (CA-film) was investigated. Fourier transform infrared spectra (FTIR) confirmed successful incorporation of chitosan and APP. The compact structure of the films was observed clearly in scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. X-ray diffraction (XRD) patterns suggest the semi-crystalline structure was increased upon addition of APP. The composite films showed an improved water resistance and vapor barrier properties, and reduced by at least 27.4% and 32.1% in swelling degree (S_d ) and water vapor permeability (WVP) compared with chitosan film (C-film), respectively. However, the transparency decreased slightly, which may be due to the shrinkage of the spacing of the polymer interchain. The composite films also displayed enhanced the mechanical properties. The antimicrobial activity of the CA-film showed an increase of at least of 0.41-fold in inhibition zone diameter for E. coli. At a concentration of 1.2 mg/mL, the antioxidant activity of CA-film was enhanced by more than threefold compared with C-film. Therefore, CA-films have good potential as sources of active packaging material for the food industry.

Lyophilized Protein Structures as an Alternative Biodegradable Material for Food Packaging

Considering the need for sustainable development in packaging production and environmental protection, a material based on lyophilized protein structures intended for frozen food packaging was produced and its selected thermophysical properties were characterized. Analyses of density, thermal conductivity and thermal diffusivity were performed and strength tests were carried out for lyophilized protein structures with the addition of xanthan gum and carboxymethyl cellulose. Packagings were made of new materials for their comparative assessment. Then, the surface temperature distribution during thawing of the deep-frozen product inside the packaging was tested. In terms of thermal insulation capacity, the best properties were obtained for sample B4 with a thermal conductivity of λ = 0.06 W∙(mK)−1), thermal capacity C = 0.29 (MJ∙(m3K)−1) and thermal diffusivity a = 0.21 (mm2∙s−1). The density and hardness of the obtained lyophilized protein structures were significantly lower compared to foamed polystyrene used as a reference material. Thermal imaging analysis of the packaging showed the occurrence of local freezing. Lyophilized protein structures obtained from natural ingredients meet the needs of consumers and are environmentally friendly. These were made in accordance with the principles of sustainable development and can be an alternative material used for the production of frozen food packaging.

Preparation and Characterization of Chitosan-Based Ternary Blend Edible Films with Efficient Antimicrobial Activities for Food Packaging Applications

To improve the mechanical and antibacterial properties of chitosan (CS) films, a ternary blend edible film was prepared by incorporating CS, gelatin (GE), and natural cinnamon essential oil (CEo). Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy, and X-ray diffraction were performed to evaluate the films. The mechanical properties, light transmission, thermal stability, hydrophilicity, and antibacterial activity of the films were also determined. The results confirmed all of the films exhibited excellent UV protection with low transparency at 600 nm. Compared with the CS films, the ternary composite film (CSGEo film, containing CS, GE, and CEo) had a higher elongation at break but a lower tensile strength. SEM images revealed that all films had smooth surfaces, although some obvious differences between CS and CSGEo films were observed by AFM. Additionally, the incorporation of GE and CEo to the films enhanced their thermal stability and contact angle, but decreased their crystallinity and wettability. The antimicrobial activity results showed that CSGEo films had excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, for which the antibacterial rate exceeded 98%. The minimum inhibitory concentrations of the CSGEo solution against E. coli and S. aureus were both 52.06 µg/mL, and the minimal bactericidal concentrations were 104.12 and 52.06 µg/mL, respectively. These results suggest that CSGEo films possess good mechanical and antibacterial properties, and therefore, their application in the food packaging industry is promising. PRACTICAL APPLICATION: The main raw materials of the edible films developed in this study are aquatic by-products, so the films are edible and biodegradable. The addition of gelatin and CEo improved the UV barrier and thermal properties but decreased the crystallinity and hydrophilicity of the films, making them suitable for use as packaging materials. CEo-incorporated films exhibited excellent mechanical properties and antibacterial activity and can, therefore, be used in the food packaging industry.

Effect of Xanthan⁻Chitosan Microencapsulation on the Survival of Lactobacillus acidophilus in Simulated Gastrointestinal Fluid and Dairy Beverage

Lactobacillus acidophilus was encapsulated in xanthan⁻chitosan (XC) and xanthan⁻chitosan⁻xanthan (XCX) polyelectrolyte complex (PEC) gels by extrusion method. The obtained capsules were characterized by X-ray diffraction and FTIR spectroscopy. The effects of microencapsulation on the changes in survival and release behavior of the Lactobacillus acidophilus during exposure to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were studied. Encapsulated Lactobacillus acidophilus exhibited a significantly higher resistance to SGF and SIF than non-encapsulated samples. In addition, the viability of free and immobilized cells of Lactobacillus acidophilus incorporated into dairy beverages was assessed for 21 days both at room temperature and in refrigerated storage. The results indicated that xanthan⁻chitosan⁻xanthan (XCX) and xanthan⁻chitosan (XC) significantly (p < 0.05) improved the cell survival of Lactobacillus acidophilus in yogurt during 21 days of storage at 4 and 25 °C, when compared to free cells.

Scale-Up Preparation and Characterization of Collagen/Sodium Alginate Blend Films

In an effort to produce scale-up of edible films, collagen-based films including different amounts of sodium alginate (CS) were prepared by casting method. Films were characterized based on their rheological, thermal, and mechanical properties, water vapor permeability (WVP), and oxygen permeability (OP). The microstructures were also evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform-infrared spectroscopy (FTIR). Furthermore, the addition of sodium alginate effectively improved the viscosity and thermal stability, significantly increased TS, and decreased E and WVP (P<0.05), but with no obvious effect on OP (P>0.05). SEM and AFM showed homogeneous matrix, with no signs of phase separation in the blends. Overall, films (CS2) produced using collagen (g) : sodium alginate (g) = 10 : 2 showed suitable rheological property (apparent viscosity was 4.87 m Pa s−1) and better TS (26.49 Mpa), E (64.98%), WVP (1.79 × 10−10 g·cm−1·s−1·Pa−1), and OP (3.77 × 10−5 cm3·m−2·d−1·Pa−1).