Preparation and functional properties of fish gelatin–chitosan blend edible films

Effect of Chitosan Edible Coating on the Biochemical and Physical Characteristics of Carp Fillet (Cyprinus carpio) Stored at -18°C

The effect of an edible coating (EC) with 1.5% chitosan as an additive, on common carp (Cyprinus carpio) fillet, was determined evaluating the biochemical, physicochemical, textural, microbiological, and nutritional characteristics periodically during its storage in the freezer (−18°C), observing a decrease in the rate of biochemical reactions related to degradation (p < 0.05), hydroperoxides content (HPC) (0.8324 nM hydroperoxides/mg of protein versus 0.5540 nM/mg with regard to the EC sample), as well as protein carbonyl content (PCC) (0.5860 nM versus 0.4743 nM of reactive carbonyl groups/mg of protein of noncoated material), keeping properties for a longer period of time, and a lower protein solubility (7.8 mg of supernatant protein/mg of total protein versus 6.8 mg/mg) and less loss of moisture (8% less, with regard to EC); for the nutritional characteristics of the fillet, lysine is the limiting aminoacid in the sample without EC, while leucine is the limiting aminoacid for the EC sample. According to microbial growth, the count was 2.2 × 10⁵ CFU/g of sample in mesophiles versus 4.7 × 10⁴ in the EC sample. The results indicate that the use of EC added with chitosan maintains the quality of the product regarding lipid and protein oxidation until fourth month of storage, maintaining moisture content without variation for at least 3 months, and inhibits microbial growth up to 2 logarithmic units, during five months of frozen storage.

Incorporating Zataria multiflora Boiss. essential oil and sodium bentonite nano-clay open a new perspective to use zein films as bioactive packaging materials

Active zein films with different levels of Zataria multiflora Boiss. essential oil were produced successfully. To enhance properties of this biopolymer for food packaging applications, sodium bentonite clay was used at two levels (2 and 4%). The results indicated that the addition of Z. multiflora Boiss. essential oil caused a reduction in tensile strength and Young's modulus and slight increase in the percent of elongation at break of the films. Maximum solubility in water and water vapor permeability was observed by incorporation of 10% Z. multiflora Boiss. essential oil in the zein matrix. Transmission electron microscopy micrographs of zein film were verified by the exfoliation of the layers of sodium bentonite clay in the zein matrix. Stronger films with lower water vapor permeability and water solubility were evident of good distribution of sodium bentonite clay in the zein matrix. According to the results, 2% sodium bentonite clay was selected for evaluation of nano active film properties. Water vapor permeability, UV light barrier, tensile strength, and Young's modulus values of active films were improved by incorporation of 2% sodium bentonite clay. The antibacterial activity of different contents of Z. multiflora Boiss. essential oil in vapor phase demonstrated that use of Z. multiflora Boiss. essential oil in the liquid phase was more effective than in vapor phase. The antibacterial zein-based films showed that active zein film with 5 and 10% Z. multiflora Boiss. essential oil had reductions of 1.68 log and 2.99 log, respectively, against Listeria monocytogenes and 1.39 and 3.07 log against Escherichia coli. Nano active zein film containing 10% Z. multiflora Boiss. essential oil and 2% sodium bentonite clay showed better antibacterial properties against L. monocytogenes (3.23 log) and E. coli (3.17 log).

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.

Chitosan treatment for skin ulcers associated with diabetes

Infections, ulcerations, gangrene and, in severe cases, extremity amputation, are common complications among diabetic subjects. Various biomaterials have been utilized for the treatment of these lesions. Chitosan is an amino sugar with a low risk of toxicity and immune response. In this study, we evaluated chitosan topical gel and film treatments for subjects with diabetic ulcerations and wounds associated with diabetes mellitus. In a pre-experimental design, we described the result of chitosan gel and film treatment for wounds and skin ulcers among patients with long-standing diabetes mellitus. We studied 8 diabetic patients with wounds and skin ulcers (long duration and Wagner degree 1–2). Initially, most lesions had some degree of infection, tissue damage and ulceration. At the end of the treatment (topical chitosan) period, the infections were cured. All patients experienced a significant improvement in the initial injury and developed granulation tissue and a healthy skin cover. This report represents one of the few published clinical experience regarding the chitosan for the treatment of skin lesions among diabetic subjects. These results are relevant and promising for the treatment of this disease.

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.

Micro- and nanoparticles by electrospray: advances and applications in foods

Micro- and nanotechnology are tools being used strongly in the area of food technology. The electrospray technique is booming because of its importance in developing micro- and nanoparticles containing an active ingredient as bioactive compounds, enhancing molecules of flavors, odors, and packaging coatings, and developing polymers that are obtained from food (proteins, carbohydrates), as chitosan, alginate, gelatin, agar, starch, or gluten. The electrospray technique compared to conventional techniques such as nanoprecipitation, emulsion-diffusion, double-emulsification, and layer by layer provides greater advantages to develop micro- and nanoparticles because it is simple, low cost, uses a low amount of solvents, and products are obtained in one step. This technique could also be applied in the agrifood sector for the preparation of controlled and/or prolonged release systems of fertilizer or agrochemicals, for which more research must be conducted.

Retardation of lipid oxidation using gelatin film incorporated with longan seed extract compared with BHT

The aim of the present work was to apply the gelatin films with different levels of longan seed extract (LS) or butylated hydroxytoluene (BHT) on retardation of lipid oxidation in soybean oil. The films incorporated with various concentrations of aqueous LS (0, 50, 100, 300, and 500 ppm) or BHT (50, and 100 ppm) were developed. The films had transmittance percentages of 60-80 % at 570 nm and showed good light barrier properties when the concentration of LS or BHT increased. About 97 % protein solubility and 41 to 54 % water solubility were obtained for the developed films. Antioxidative activity of gelatin films incorporated with LS increased markedly with increasing storage time as indicated by the increase in DPPH radical scavenging activity (41-50 %) (P < 0.05). Films incorporated with LS or BHT showed the preventive effect on lipid oxidation of soybean oil during 30 days of storage. At the level of 500 ppm, LS provided the highest efficacy for lipid oxidation retardation as evidenced by lower conjugated diene (CD) values (P > 0.05). According to these findings, gelatin film incorporated with longan seed extract or BHT could be used as a tool to prolong the shelf-life of oily foods.

Barrier, structural and mechanical properties of bovine gelatin-chitosan blend films related to biopolymer interactions

BACKGROUND

The increased use of synthetic packaging films has led to a high ecological problem due to their total non-biodegradability. Thus, there is a vital need to develop renewable and environmentally friendly bio-based polymeric materials. Films and coatings made from polysaccharide polymers, particularly chitosans and gelatins have good gas barrier properties and are envisaged more and more for applications in the biomedical and food fields, as well as for packaging. In this study a casting method was used to develop an edible plasticised film from chitosan and gelatin. Aiming to develop a blend film with enhanced properties, the effects of mixing chitosan (CS) and gelatin (G) in different proportions (CS:G, 75:25, 50:50, 25:75, w/w) on functional and physico-chemical properties have been studied.

RESULTS

Mean film thickness increased linearly (R2 =0.999) with surface density of the film forming solution. An enhancement of mechanical properties by increasing the tensile strength (38.7±11 MPa for pure chitosan and 76.8±9 MPa for pure gelatin film) was also observed in blends, due to gelatin content.When the gelatin content in blend filmswas increased an improvement of both water vapour barrier properties [(4±0.3)×10(-10) g m(-1) s(-1) Pa(-1) for pure chitosan and (2.5±0.14)×10(-10) g m(-1) s(-1) Pa(-1) for pure gelatin, at 70% RH gradient] and oxygen barrier properties ((822.62±90.24)×10(-12) g m(-1) s(-1) Pa(-1) for blend film chitosan:gelatin (25:75 w/w) and (296.67±18.76)×10(-12) g m(-1) s(-1) Pa(-1) for pure gelatin was observed. Fourier transform infrared spectra of blend films showed a shift in the peak positions related to the amide groups (amide-I and amide-III) indicating interactions between biopolymers.

CONCLUSIONS

Addition of gelatin in chitosan induced greater functional properties (mechanical, barrier) due to chemical interactions, suggesting an inter-penetrated network.