Chitosan-based Coatings Research Articles

Chitosan-Based Antimicrobial Coating for Improving Postharvest Shelf Life of Pineapple

Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers and handlers. Chitosan-based coatings on fruit surfaces have gained importance in recent years to enhance postharvest shelf life of the fruits. In this study, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles. The developed formulation was applied on the surface of freshly harvested pineapple fruits. ZnO nanoparticles were used as an antimicrobial agent. Coated pineapple fruits were evaluated for weight loss, total soluble solids, titratable acidity, decay index, maturity index, and sensory attributes, including visual appearance, periodically at 5 day interval during storage. The results showed that the coating of the fruit reduced weight loss by about 5%, and also delayed ripening and oxidative decay compared to the uncoated fruit. Thus, the developed coating formulation is a promising sustainable solution to reduce postharvest losses and to extend shelf life of pineapples.

The chitosan-based bioactive composite coating on titanium

This paper describes a promising electrophoretic deposition (EPD) approach for developing composite coatings based on chitosan with the additional components of hydroxyapatite, graphene, and gentamicin on titanium substrate. Bioactive properties were investigated in vitro by immersing the coatings in simulated body fluid (SBF) at 37 °C. The newly formed biomimetic layer on the top of the deposited chitosan-based coatings on Ti was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and electrochemical measurements, while coatings' bioactivity was proved by alkaline phosphatase activity assay in MRC-5 and L929 tested cell lines. The biocompatibility towards MRC-5 and L929 cell lines was investigated by dye exclusion test (DET) implying the non-cytotoxic effect of coatings. Gentamicin release studies were monitored during 21-day by high-performance liquid chromatography coupled with mass spectrometry, indicating rapid release of gentamicin (≈40%) in the first 48 h and more than 60% after 14 days.

Antimicrobial potential of a bioactive coating based on chitosan incorporated with clove essential oil in hamburger-like meat product

The food industry is looking for strategies to prevent microbial growth in order to ensure food safety and shelf life. However, the use of synthetic preservatives, such as nitrate and nitrite in meat products, entails risks to human health. An alternative is the utilization of essential oils, widely known for their antimicrobial properties. This work aimed the antimicrobial potential of a bioactive coating based on chitosan incorporated with clove essential oil in in hamburger-like meat product. Through the analysis of antimicrobial activity by diffusion in agar and broth, there was an action against Gram-positive and Gram-negative bacteria. Regarding Staphylococcus aureus and Escherichia coli, the minimum inhibitory concentration (MIC) was 3.74 mg/mL and the minimum bactericidal concentration (MBC) was 374.33 mg/mL for both. In the micro atmospheric diffusion test, CEO reduced by up to 70 and 76% of the E. coli and S. aureus bacteria development, respectively. CEO was applied as an active component in chitosan-based coatings in hamburger-like meat, in which it was able to promote the control of microbial proliferation of Total Coliforms, Coliforms at 45 ⁰C and Coagulase-Positive Staphylococcus throughout 7 days of storage under refrigeration. It is concluded that the bioactive coating based on chitosan incorporated with clove essential oil promotes microbiological control in hamburger-like meat product.

Plant Byproducts as Part of Edible Coatings: A Case Study with Parsley, Grape and Blueberry Pomace.

Studies dealing with the development of edible/biodegradable packaging have been gaining popularity since these commodities are marked as being ecofriendly, especially when byproducts are incorporated. Consequently, this study aimed at the development of chitosan-based coatings with plant byproducts. Their sensory properties, colour attributes, occurrence of cracks in microstructure and biodegradability were analysed. Coatings containing grape and blueberry pomace had statistically significantly (p < 0.05) higher levels of colour intensity. Coating samples were characterised by lower aroma intensity (3.46–4.77), relatively smooth surface (2.40–5.86), and low stickiness (2.11–3.14). In the overall hedonic evaluation, the samples containing parsley pomace in all concentrations and a sample containing 5% grape pomace achieved a statistically significantly (p < 0.05) better evaluation (5.76–5.93). The lowest values of the parameter ΔE2000 were recorded for the sample containing 5% parsley pomace (3.5); the highest was for the sample with 20% blueberry pomace (39.3). An analysis of the coating surface microstructure showed the presence of surface cracks at an 80 K magnification but the protective function of the edible coating was not disrupted by the added plant pomace. The produced samples can be considered to have a high biodegradability rate. The results of our experimentally produced coatings indicate their possible application on a commercial scale.

Corrosion Resistance of MgZn Alloy Covered by Chitosan-Based Coatings.

Chitosan coatings are deposited on the surface of Mg20Zn magnesium alloy by means of the spin coating technique. Their structure was investigated using Fourier Transform Infrared Spectroscopy (FTIR) an X-ray photoelectron spectroscopy (XPS). The surface morphology of the magnesium alloy substrate and chitosan coatings was determined using Scanning Electron Microscope (FE-SEM) analysis. Corrosion tests (linear sweep voltamperometry and chronoamperometry) were performed on uncoated and coated magnesium alloy in the Hank’s solution. In both cases, the hydrogen evolution method was used to calculate the corrosion rate after 7-days immersion in the Hank’s solution at 37 °C. It was found that the corrosion rate is 3.2 mm/year and 1.2 mm/year for uncoated and coated substrates, respectively. High corrosion resistance of Mg20Zn alloy covered by multilayer coating (CaP coating + chitosan water glass) is caused by formation of CaSiO3 and Ca3(PO4)2 compounds on its surface.

In vitro biological and antimicrobial properties of chitosan-based bioceramic coatings on zirconium

Ca-based porous and rough bioceramic surfaces were coated onto zirconium by micro-arc oxidation (MAO). Subsequently, the MAO-coated zirconium surfaces were covered with an antimicrobial chitosan layer via the dip coating method to develop an antimicrobial, bioactive, and biocompatible composite biopolymer and bioceramic layer for implant applications. Cubic ZrO2, metastable Ca0.15Zr0.85O1.85, and Ca3(PO4)2 were detected on the MAO surface by powder-XRD. The existence of chitosan on the MAO-coated Zr surfaces was verified by FTIR. The micropores and thermal cracks on the bioceramic MAO surface were sealed using a chitosan coating, where the MAO surface was porous and rough. All elements such as Zr, O, Ca, P, and C were homogenously distributed across both surfaces. Moreover, both surfaces indicated hydrophobic properties. However, the contact angle of the MAO surface was lower than that of the chitosan-based MAO surface. In vitro bioactivity on both surfaces was investigated via XRD, SEM, and EDX analyses post-immersion in simulated body fluid (SBF) for 14 days. In vitro bioactivity was significantly enhanced on the chitosan-based MAO surface with respect to the MAO surface. In vitro microbial adhesions on the chitosan-based MAO surfaces were lower than the MAO surfaces for Staphylococcus aureus and Escherichia coli.

Functionalization of Silver/Titanium Dioxide Composites in Chitosan-based Coatings and their Egg Preservation Performances

Eggs are an excellent source of proteins, minerals, and vitamins, which have been popularly consumed in daily diet all over the world. The micro-pores and micro-cracks on the eggshells, however, lead to the loss of moisture and the escape of CO2, resulting in the acceleration of egg deterioration and economic loss. To enhance the stability and sterilizability of the existing chitosan-based coating materials and to develop novel multifunctional nano-composites for anti-bacterial and egg preservation, silver/titanium dioxide (Ag/TiO2) composites are synthesized and applied to modify chitosan for the extension of the egg shelf life. Electron microscope (SEM) images are used to analyze the structure and morphology of composite particles and the morphology of coated eggshells. The preservation performances of composite coatings are evaluated by various parameters: weight loss, Haugh unit, albumen pH and eggshell morphologies of the samples. Adoption of Ag/TiO2 composites contributes to a synergistic effect to chitosan, which could prolong the preservation period further. The performances of chitosan coating, however, are presently limited by the existing particle species and concentration, which requires optimization in future studies. Methods in this study examine novel coating materials, which could be created by adding specific nanoparticles into the coating precursor, to achieve the combinative effects of the nanoparticle and the precursor, as well as to prepare novel multifunctional coatings in the field of food preservation.

Multifunctional Role of Chitosan Edible Coatings on Antioxidant Systems in Fruit Crops: A Review.

Chitosan-based edible coatings represent an eco-friendly and biologically safe preservative tool to reduce qualitative decay of fresh and ready-to-eat fruits during post-harvest life due to their lack of toxicity, biodegradability, film-forming properties, and antimicrobial actions. Chitosan-based coatings modulate or control oxidative stress maintaining in different manner the appropriate balance of reactive oxygen species (ROS) in fruit cells, by the interplay of pathways and enzymes involved in ROS production and the scavenging mechanisms which essentially constitute the basic ROS cycle. This review is carried out with the aim to provide comprehensive and updated over-view of the state of the art related to the effects of chitosan-based edible coatings on anti-oxidant systems, enzymatic and non-enzymatic, evaluating the induced oxidative damages during storage in whole and ready-to-eat fruits. All these aspects are broadly reviewed in this review, with particular emphasis on the literature published during the last five years.

Tyrosol-Enriched Tomatoes by Diffusion across the Fruit Peel from a Chitosan Coating: A Proposal of Functional Food.

Chitosan is receiving increasing attention from the food industry for being a biodegradable, non-toxic, antimicrobial biopolymer able to extend the shelf life of, and preserve the quality of, fresh food. However, few studies have investigated the ability of chitosan-based coatings to allow the diffusion of bioactive compounds into the food matrix to improve its nutraceutical quality. This research is aimed at testing whether a hydrophilic molecule (tyrosol) could diffuse from the chitosan-tyrosol coating and cross the tomato peel. To this end, in vitro permeation tests using excised tomato peel and an in vivo application of chitosan-tyrosol coating on tomato fruit, followed by tyrosol quantification in intact fruit, peel and flesh during a seven-day storage at room temperature, were performed. Both approaches demonstrated the ability of tyrosol to permeate across the fruit peel. Along with a decreased tyrosol content in the peel, its concentration within the flesh was increased, indicating an active transfer of tyrosol into this tissue. This finding, together with the maintenance of constant tyrosol levels during the seven-day storage period, is very promising for the use of chitosan formulations to produce functional tomato fruit.

Dual-purpose surface functionalization of Ti-6Al-7Nb involving oxygen plasma treatment and Si-DLC or chitosan-based coatings

The work presents a detailed study on the diamond-like structures doped with Si atoms and biopolymers-based coatings (chitosan, alginate) enriched with Ag nanoparticles (Ag NPs) deposited on the Ti-6Al-7Nb substrate. Multilayers were obtained by Plasma Enhanced Radio Frequency Chemical Vapour Deposition (PE RF CVD) technique and subsequent deposition of biopolymers by immersion method. The impact of Si atoms and Ag NPs on chemical structure, microstructure, topography, cytotoxicity as well as the hardness and Young modulus of the resulting layers was precisely investigated. The most advantageous conditions of plasma functionalization in RF reactor were the mixture of O2-Ar-NH3 in volume ratio of 10/1/9 in the first stage of functionalization (pre-activation). In the case of Si-DLC coatings (up to ca. 19 at.%) the lower silane flow (4 cm3/min) resulted in significant decrease of surface roughness (up to ca. Ra = 0.71 nm) of modified surfaces and increase of hardness reaching ca. 900 nm depth into surface (up to ca. 16 GPa). The most attractive among biopolymer-based coating on Ti-6Al-7Nb in terms of biological activity was chitosan with Ag NPs (diameter of ca. 25 nm) with additional alginate layer. AFM analysis revealed a uniform distribution of Ag NPs in the chitosan matrix. This contributed to advantageous physicochemical and biological properties assuring proper cell adhesion and proliferation. Noteworthy, the resulting surface functionalization of Ti-6Al-7Nb alloy did not cause significant cytotoxicity in vitro, giving a strong hope for perspective applications in implantology.

Impact of chitosan-based coatings on myofibrillar protein denaturation, muscle microstructure and lipid oxidation of oyster (Crassostrea hongkongensis) during 0 °C storage

ABSTRACT The changes in myofibrillar protein, muscle microstructure, and lipid oxidation of oysters (Crassostrea hongkongensis) treated with chitosan-based coatings (CP-0°C) or aseptic water (CG-0°C) for 20 days storage at 0°C were investigated. Compared to the CG-0°C at day 20, the higher total sulfhydryl group content (83.24%), unfrozen water content (39.24%), and Ca2+-ATPase activity (96.79%) along with the lower myofibrillar protein solubility (80.15%) indicated that CP-0°C protected oysters from protein denaturation. Similarly, the CP-0°C better maintained muscle microstructure shown by the relatively higher quality of muscle and less ice crystals. Meanwhile, CP-0°C prevented lipid hydrolysis and oxidation, as evidenced by the lower contents of fatty acid (FA) content (total content of 12.16 ± 1.02 mg/g wet weight at day 20), peroxide value (POV) (15.13 meq oxygen/Kg lipid at day 20), and thiobarbituric acid-reactive substances (TBARS) (1.79 mg MDA eq/Kg sample at day 20) in CP-0°C. These results imply that CP-0°C could protect the quality of chilled oysters stored at 0°C.

Chitosan-Based Coatings Incorporated with Cinnamon and Tea Extracts to Extend the Fish Fillets Shelf Life: Validation by FTIR Spectroscopy Technique

The aim of this study was to evaluate the effect of active coatings prepared from the chitosan on the quality parameters of fish fillets. Antimicrobial and antioxidant properties were improved by addition of tea and cinnamon extracts. Different quality parameters including free fatty acids (FFA), thiobarbituric acid value (TBA), trimethylamine (TMA), total volatile basic nitrogen (TVBN), whiteness, and pH of coated and noncoated samples were evaluated during storage for 20 d at 5 ± 1°C. Moreover, FTIR characterization (i.e., wavenumber and absorbance values) was used to investigate the oxidative stability. Extracts addition to chitosan coating had noticeable influence on reducing FFA and TBA. Moreover, modified chitosan coating decreased TVBN and TMA significantly. Based on FTIR finding, control sample showed the highest oxidation value, while the treated samples with chitosan\incorporated with tea and cinnamon extracts (CTCECS) had the lowest oxidation. The results showed that FTIR technique could be successfully applied to monitor the lipid oxidation of fish fillet. Therefore, FTIR provides a fast approach to study the compositional changes of food products rather than conventional chemical analysis. The findings of our research showed that chitosan coating modified with tea and cinnamon extracts could be used as a novel active packaging to prolong the shelf life quality of fish fillet.

Chitosan nanocomposite coatings with enhanced corrosion inhibition effects for copper

A biopolymer coating on copper was prepared based on chitosan nanocomposite and its corrosion inhibition efficiency was investigated. Inclusion of silica nanoparticles substantially reduces swelling ratio of chitosan coating while enhancing its thermal stability. The corrosion resistance of chitosan-based coatings is improved by introducing 2-mercaptobenzothiazole and silica in the matrix. It is found that upon crosslinking the chitosan coatings, a higher corrosion resistance could be achieved and the highest inhibition efficiency for chitosan nanocomposite coatings is calculated as 85%. The corrosion mechanism is found closely related to mass transition and diffusion process, and also the polarization resistance contributes to the impedance. Calculated impedance using Kramers-Kronig transformation shows good agreement with experimental values, thus validating the impedance measurements. This study exhibits the enhanced efficiency of nanocomposite and potential of chitosan coatings in corrosion prevention for copper.

Effects of Different TiO2 Nanoparticles Concentrations on the Physical and Antibacterial Activities of Chitosan-Based Coating Film

In this investigation, the effect of different concentrations of titanium dioxide (TiO2) nanoparticles (NPs) on the structure and antimicrobial activity of chitosan-based coating films was examined. Analysis using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the modified TiO2 NPs were successfully dispersed into the chitosan matrix, and that the roughness of the chitosan-TiO2 nanocomposites were significantly reduced. Moreover, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses indicated that the chitosan interacted with TiO2 NPs and possessed good compatibility, while a thermogravimetric analysis (TGA) of the thermal properties showed that the chitosan-TiO2 nanocomposites with 0.05% TiO2 NPs concentration had the best thermal stability. The chitosan-TiO2 nanocomposite exhibited an inhibitory effect on the growth of Escherichia coli and Staphylococcus aureus. This antimicrobial activity of the chitosan-TiO2 nanocomposites had an inhibition zone ranging from 9.86 ± 0.90 to 13.55 ± 0.35 (mm). These results, therefore, indicate that chitosan-based coating films incorporated with TiO2 NPs might become a potential packaging system for prolonging the shelf-life of fruits and vegetables.

Bovine jugular vein valved conduit: A new hybrid method of devitalization and protection by chitosan-based coatings using super- and subrcritical СО2

Here we report on the structure and mechanical properties of native bovine jugular veins (BJVs). The veins were pretreated with co-solvents in supercritical (sc) CO2 and cross-linked by glutaraldehyde veins coated with chitosan from solutions in carbonic acid). The novel hybrid treatment method was developed using rapid processing in SDS (1 h) and treatment in scCO2 adding the non-ionic detergent (Tween-80) (1 h). The hybrid method allows to decellularize the tissue completely, preserving the structure of the extracellular matrix, and at the same time to significantly increase the elasticity of vein tissue, bringing it closer to the human pulmonary artery in its properties (E∼8 MPa). Protective chitosan-based coatings, deposited onto the tissue (∼0.8 wt% for chitosan, 0.45% for chitosan/Ag nanoparticles (AgNPs)) from the water/subcritical CO2 system (3 h), mask free aldehyde groups, smooth the surface of veins and maintain the elastic properties of the tissue.

Efficient reinforcement of chitosan-based coatings for Ricotta cheese with non-toxic, active, and smart nanoparticles

We developed new smart and active nanoparticles with a thermal sensing core and antibacterial, antioxidant, and UV-absorbing shell. Incorporation of the newly designed nanoparticles into the chitosan matrix in a CS:NPs mass ratio 1:0.5 results in advanced nanocomposite food coatings, which possess enhanced mechanical and barrier properties, together with higher antibacterial, antioxidant, and UV-absorbing activity. Moreover, the resultant food coatings are non-toxic. Thus, we prepared new food coatings, in which active (antibacterial, antioxidant, UV-absorbing) and smart (temperature sensitive) properties are enabled by the same single type of nanoparticles. The developed food coatings are efficient for the prolongation and improvement of shelf life of Ricotta cheese.

The synergistic effect of an imidazolium salt and benzotriazole on the protection of bronze surfaces with chitosan-based coatings

The class of imidazolium salts contains effective anticorrosion additives for metal substrates. This study evaluated the potential of 1-carboxymethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (HO2CC1MImNTf2) for application in cultural heritage, exploring it as anticorrosion additive in chitosan-based coatings for the protection of copper-based alloys. Under accelerated corrosion conditions with HCl vapor, the chitosan coating with HO2CC1MImNTf2 was less effective than the one with benzotriazole. The coating with a combination of HO2CC1MImNTf2 and benzotriazole resulted in the optimal protective efficacy of the bronze surface, and it also maintained high transparency without changing the bronze appearance.

Impact of chitosan/noble metals-based coatings on the plasmochemically activated surface of NiTi alloy

After plasmochemical activation, chitosan-based coatings (containing silver or gold nanoparticles) were applied on nitinol (NiTi) alloy surface to study the effect of this functionalization on i) wettability, ii) corrosion resistance, iii) release of metal ions, and iv) cytotoxicity. Surface modification of nitinol based on (1) Ar/O2/NH3 plasma treatment and deposition of chitosan/AgNPs/vit.C coating (CS/AgNPs) or (2) Ar/O2/NH3 plasma treatment and deposition of chitosan/AuNPs coating (CS/AuNPs) resulted in decrease in water contact angle (enhanced hydrophilicity), increase in surface roughness parameters, improvement of corrosion resistance, and good biocompatibility (proved on human osteoblast-like cells in vitro), when compared to both unmodified NiTi and the chitosan layer itself. The proposed surface functionalization can potentially be a powerful and promising strategy for reducing pathogenic microorganism-associated infections without harmful effects towards mammalian cells, thus facilitating proper osseointegration.

Layer by layer coating for bio-functionalization of additively manufactured meta-biomaterials

Additive manufacturing has facilitated fabrication of complex and patient-specific metallic meta-biomaterials that offer an unprecedented collection of mechanical, mass transport, and biological properties as well as a fully interconnected porous structure. However, applying meta-biomaterials for addressing unmet clinical needs in orthopedic surgery requires additional surface functionalities that should be induced through tailor-made coatings. Here, we developed multi-functional layer-by-layer coatings to simultaneously prevent implant-associated infections and stimulate bone tissue regeneration. We applied multiple layers of gelatin- and chitosan-based coatings containing either bone morphogenetic protein (BMP)-2 or vancomycin on the surface of selective laser melted porous structures made from commercial pure Titanium (CP Ti) and designed using a triply periodic minimal surface (i.e., sheet gyroid). The additive manufacturing process resulted in a porous structure and met the the design values comparatively. X-ray photoelectron spectroscopy spectra confirmed the presence and composition of the coating layers. The release profiles showed a continued release of both vancomycin and BMP-2 for 2–3 weeks. Furthermore, the developed meta-biomaterials exhibited a very strong antibacterial behavior with up to 8 orders of magnitude reduction in both planktonic and implant-adherent bacteria and no signs of biofilm formation. The osteogenic differentiation of mesenchymal stem cells was enhanced, as shown by two-fold increase in the alkaline phosphatase activity and up to four-fold increase in the mineralization of all experimental groups containing BMP-2. Eight-week subcutaneous implantation in vivo showed no signs of a foreign body response, while connective tissue ingrowth was promoted by the layer-by-layer coating. These results unequivocally confirm the superior multi-functional performance of the developed biomaterials.

Effects of chitosan-based coatings on storage quality of Chinese shrimp.

We investigated the effects of chitosan‐based coatings on the preservation quality of refrigerated Chinese shrimp for 12 days. Samples of Chinese shrimp were subjected to three different coating treatments, namely chitosan (CH), chitosan and ε‐polylysine (CH + ε‐PL), chitosan combined with ε‐polylysine and carrageenan (CH + ε‐PL + CA), and compared with a control. The bacteriological characteristics [total viable count (TVC)], chemical indexes including pH, thiobarbituric acid (TBA) value, K‐value, and total volatile basic nitrogen (TVB‐N), texture (hardness, chewiness, and elasticity), and sensory changes were assessed. The increases in TVC, pH, TBA, K‐value, and TVB‐N were observed to be delayed by preservation treatments, and the textural and sensory characteristics indicated that the treated shrimp were preserved more effectively than the control. Treatment with chitosan combined with ε‐polylysine and carrageenan was the most effective preservation method than treatment with chitosan alone or chitosan and ε‐polylysine; the shelf life was also prolonged. Therefore, treatment with chitosan combined with ε‐polylysine and carrageenan is proposed as a potential method for shelf life extension of Chinese shrimp for refrigerated storage.