Summary
The addition of nisin into a gelatin matrix can change properties of the film. The aim of this work was to develop gelatin‐based films containing different nisin concentrations in order to ...study their influence on the film's antimicrobial and physical properties and their rheological properties as a film‐forming solution (FFS). The FFS was characterised by rheological assays, and the gelatin‐based active films were characterised and assessed by the effects of nisin concentrations on their various properties, including antimicrobial activity. Nisin's concentration affected not only its viscoelastic properties of FFS but also its film solubility in water, film surface roughness and light barrier. The addition of nisin also slightly modified the water contact angle and the mechanical properties of the gelatin films. Finally, the films demonstrated activity against Staphylococcus aureus and Listeria monocytogenes at concentrations above 56 mg of nisin g−1 of gelatin.
Gelatin‐based films with nisin content above 56 mg/100 g of gelatin show antimicrobial activity. Active gelatin‐based films inhibit Staphylococcus aureus and Listeria monocytogenes. The presence of nisin in the gelatin matrix does not damage film properties. Nisin and gelatin possess good compatibility because they are peptides.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The aim of this study was to evaluate the effect of the incorporation of water-in-oil-in water (W/O/W) double emulsion (DE) loaded with “pitanga” leaf hydroethanolic extract on the physicochemical, ...antimicrobial and antioxidant properties of films based on gelatin, chitosan and gelatin/chitosan blend to target the future application of these films as active food packaging. Scanning electron microscopy and atomic force microscopy images of the films showed that the presence of DE caused heterogeneity on the surface and internal structure. As a consequence, the decrease in the gloss and the water drop contact angle of films was caused mainly by the increase in surface roughness. In addition, the DE significantly improved the UV/Vis light barrier property of the films. The DE increased the strength and stiffness of the films based on gelatin and chitosan, but decreased those properties in the gelatin/chitosan blend, and increased the extensibility of all films, in addition to decreasing water solubility, water vapor permeability and opacity. Films with DE showed high antioxidant activity, but only the films based on gelatin and with DE inhibited Staphylococcus aureus. The other films containing DE inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella ssp bacteria just in the region of contact with the films.
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•Pitanga leaf hydroethanolic extract (PLHE) is a good source of bioactive agents.•Double emulsion encapsulating PLHE activated films based on biopolymers.•These active films were transparent but with high UV/Vis light barrier property.•Active films had limited antimicrobial activity but high antioxidant activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The effects on surface properties of films with compositions based on gelatin plasticized with glycerol, without or with montmorillonite (MMT), and plasticized with acetyl tributyl citrate (ATC) was ...investigated. The water contact angle (WCA), wettability and free surface energy were determined by measuring the WCA using the sessile drop method. The surface topography was measured by AFM. The film plasticized by glycerol presented the smoothest surface, while the film loaded with MMT presented the greatest surface roughness followed by that plasticized by ATC. All films showed a hydrophobic character (WCA>65°), and the same trend was observed for wettability. It is worth mentioning that there was no significant correlation between the values of WAC and roughness. The films showed low polar component values, which corroborate the high WCA values obtained. In conclusion, the MMT load or the use of ATC did not expressively improve the humidity resistance of films based on gelatin.
•Wettability of gelatin-based films with different compositions have been assessed.•No effect of the surface roughness on water contact angle of the gelatin film.•Gelatin-based films presented surface with hydrophobic character.•No effect of montmorillonite on the surface wettability of gelatin/glycerol film.•Gelatin film with acetyl tributyl citrate showed the lowest surface hydrophobicity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Summary
The objective of this study was to evaluate the influence of pH on rheological and viscoelastic properties of solutions based on blends of type A (GeA) or type B (GeB) gelatin and chitosan ...(CH). Solutions of GeA, GeB, CH, GeA:CH, and GeB:CH were prepared in several pH (3.5–6.0) and analyzed for determination of zeta‐potential. Rheological analyses (stationary and dynamic essays) were carried out with blends allowing to study the effect of pH on shear stress, apparent viscosity, loss (G”) and storage (G’) moduli, and angle phase (Tanδ). Zeta potential of all biopolymers decreased linearly as a function of pH. CH presented higher values, and GeB, the lowest one, being the only having negative values at pH > 5. Overall, the pH influenced the rheological and viscoelastic properties of the colloidal solutions: shear stress and apparent viscosity increased as a function of pH. Other assays were carried out at 3% and 5% strain, for GeA:CH and GeB:CH, respectively. In the sol domain, G’ and G” (1 Hz) increased linearly for GeA:CH. But for GeB:CH, they increased in two linear different regions: one function between pH 3.5 and 5.0 and another one between 5.0 and 6.0, being a more important effect was visible in this last domain probably due to the negative net charge of gelatin, above it pI. An effect in two domains was also visible for Tanδ, explained in the same manner as previously. The GeB:CH blends behaved like diluted solutions, and transition temperatures increased as a function of pH.
Rheological and viscoelastic properties of colloidal solutions based on gelatins and chitosan as affected by pH.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The aim of this research was to study the effect of Laponite concentration on some physical and morphological properties of gelatin films produced by casting technique. The studied properties were ...thickness, gloss, color, opacity, moisture content, solubility in water, water vapor permeability, microstructure, crystallinity, chemical structure, and thermal and mechanical properties. The results suggested that the mechanical properties (elastic modulus, tensile strength and puncture force) of gelatin matrix were significantly improved with the increase of the concentration of Laponite. Others properties such as surface rugosity and solubility in water also were altered with the increase of the concentration of Laponite. X-ray analyses suggested a good dispersion of Laponite into gelatin matrix, confirmed by atomic force microscopy micrographs. The analysis by Fourier transform infrared spectroscopy revealed the alterations of bands at 1080 and 997cm−1 with Laponite addition to the gelatin matrix. Laponite gelatin nanocomposite films could be potentially used as a novel packaging in food and pharmaceutical industries.
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•Laponite gelatin nanocomposite films have potential industrial applications.•Exfoliated platelets of Laponite in gelatin matrix•Laponite enhances the mechanical properties in gelatin matrix.•Laponite does not alter optical properties in gelatin matrix.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Chitosan-coated microparticles were prepared to encapsulate antioxidant rutin.•Active films were made by incorporating chitosan-coated microparticles into gelatin.•Prepared films ...showed proper dispersion of the microparticles into the gelatin matrix.
The aim of this study was development an active film based on gelatin incorporated with antioxidant, rutin carried into microparticles. The complexation between oppositely charged lecithin and chitosan was applied to prepare the chitosan-coated microparticles. The generated microparticles had an average size of 520±4nm and a span of 0.3 were formulated by a rotor-stator homogenize at the homogenization speed 10,000rpm. Composite films were prepared by incorporating chitosan-coated microparticles, at various concentrations (0.05, 0.1, 0.5, or 1% (based on the weight of the gelatin powder)) in the gelatin-based films. For the prepared films, the results showed that obtained physicochemical, water vapor barrier, and mechanical were compared with native gelatin film with a slight decrease for chitosan concentration higher than 0.5%. The microstructure studies done by scanning electron microscopes, revealed different micropores embedded with oil resulting from the incorporation of the microparticles into the gelatin matrix. Moreover, the calorimetric results were comparable to those of gelatin control film with Tg value 45°C and increased crystallinity percentage with increasing incorporation of microparticles. This original concept of composite biodegradable films may thus be a good alternative to incorporate liposoluble active compounds to design an active packaging with good properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Active films present high barrier to UV light and antioxidant properties.•Rheological properties of the FFS were not affected by the additives.•Structural heterogeneities due to Natamycin caused ...brittleness in active films.•Cassava starch/chitosan active films with Natamycin present antifungal activity.
Active edible coatings and films produced by addition of plant extracts and antimicrobial compounds are of interest for food packaging. The aim of this work was to develop and characterize film-forming solution and film based on blends of cassava starch/chitosan (CS/CH) incorporated with pitanga (Eugenia uniflora L.) leaf extract (PE) and/or natamycin (NA), produced by casting, and studying their effect on selected physical properties, and antioxidant and anti-fungal activities of films. The addition of PE did not affect the film mechanical properties, whereas NA significantly decreased the flexibility of films due to changes in biopolymer behavior from ductile to brittle. Structural analyses by FTIR and XRD indicated interaction among the components particularly with presence of new CO vibration peaks and shift in the characteristic CS/CH blend wave numbers. The antioxidant activity of films increased significantly with PE although the combination of additives resulted in activity reduction. Positive anti-fungal effect of NA containing films was observed against Aspergillus flavus and Aspergillus parasiticus, indicating potential for active food packaging applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Nanoemulsion of ginger essential oil (GEO) was produced by microfluidization.•Edible films reinforced with montmorillonite (MMT) was activated with GEO emulsion.•Films microstructure ...strongly affected by the GEO and/or MMT.•Films with GEO plus MMT presented improved characteristics and antioxidant activity.•Films may have practical application on food packing sector.
Montmorillonite (MMT) and nanoemulsioned ginger essential oil (GEO) were incorporated into gelatin-based films to produce activated films with improved physical properties, with potential for food packaging applications. Nanoemulsions prepared with 1, 3 or 5% of GEO presented similar characteristics. Rheological properties of film-forming solutions were slightly affected by the concentration of GEO used. The incorporation of MMT and GEO into gelatin-based films increased the thickness and decreased the solubility in water, moisture content and superficial hydrophobicity of films (only with MMT). However, the combined effect of MMT and GEO improved significantly (p<0.05) the elongation at break, puncture force and puncture deformation of gelatin-based films. The presence of MMT increased the roughness of the films and slightly reduced their crystallinity. The nanocomposite and activated films presented antioxidant activity but not antimicrobial activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The objective of this study was to develop an active nanocomposite gelatin-based film in an automatic spreader in order to improve production, which is normally done by casting. The study was divided ...in two steps: (1) first, the effect of a nanocomposite-forming solution formulation on the rheological properties and on some physical properties of gelatin-based nanocomposite films (GNF) was evaluated using a response surface methodology (RSM); (2) then, the effect of potassium sorbate concentration on some GNF properties, previously chosen by RSM, was assessed. RSM, a 23+α factorial design, was used to study and to optimize the effect of three important variables, gelatin concentration (CG), plasticizer concentration (CP) and montmorillonite concentration (CN), on the rheological properties of a nanocomposite-forming solution, and on the properties of the films (mechanical and barrier properties). Films were prepared by casting in an automatic spreader. According to the results of the analysis of variance (ANOVA), in general, nanoparticle incorporation improved the mechanical properties of GNF. However, this improvement was not always proportional to the addition of the nanoparticles, since there is a maximum concentration limit. From the results obtained in the first step of the study, it was possible to optimize a formulation in order to study the effect of potassium sorbate concentration on GNF properties. At the range of concentration studied (5–15%), incorporation of the antimicrobial agent potassium sorbate in the GNF produced significant changes in the mechanical properties and solubility in water of the films. However, despite the hydrophilic characteristic of the antimicrobial compound, moisture content of the films was not affected. It could be concluded that potassium sorbate presented a plasticizer effect in the films, enabling greater molecular chain mobility and, therefore, affecting mechanical properties and solubility in water. The study of the quality of nanoparticle dispersion in the biopolymer matrix is a key strategy that may help researchers to better understand the effect of nanoparticle addition in biopolymer matrices. Spreading technique produced films similar to those produced by casting.
•Gelatin-based nanocomposite films were produced by casting in an automatic spreader.•Nanoparticle incorporation improved the mechanical properties of films.•Incorporation of potassium sorbate produced significant changes in films properties.•Spreading technique produced films similar to those produced by casting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•The montmorillonite changes the sol-gel transitions of gelatin-based solutions.•The nanocomposite-forming solution (in sol domain) presents a non-Newtonian.•The mean diameter and ζ-potential of ...nanoparticle dispersed in water varies with its concentration.•The behavior of gelatin-based solution can be due to formation of coacervates.
Interested in developing gelatin-based nanocomposites using a spreading technique, this research aimed to study the effect of nanoparticles concentration on the rheological properties of nanocomposite-forming solutions (NFS) based on gelatin and montmorillonite (MMT). The NFS were produced with 5 and 8g gelatin/100g NFS; 30g glycerol/100g gelatin and 0, 5, 10 and 15g MMT/100g gelatin. Rheological tests were carried out in an AR2000 rheometer. Also, the dispersions of MMT in water were analyzed to determine the pH, the mean diameter, and the ζ-potential. The MMT concentration affected significantly the mean diameter of the dispersed nanoparticles, but only affected the ζ-potential for the 5% gelatin system. The MMT dispersions presented Newtonian behavior with low viscosity. The NFS presented viscoelastic behavior. The sol–gel and gel–sol transition temperatures were affected by the MMT concentration. Moreover, the NFS in the sol domain presented a non-Newtonian behavior affected by the MMT concentration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
