The bioconversion of fish by-products through the development of biodegradable films offers the possibility to their valorization and, on the other side, to decrease the use of synthetic packaging, ...responsible for several ecological problems due to their non-biodegradability. Thus, in the present study, blend films (Bl-F) and bilayer films (Bi-F) based on commercial bovine gelatin (CBG) and smooth-hound viscera proteins, incorporated or not with sulfated polysaccharides (SP) or smooth-hound peptides (SHP) with molecular weight below 1 kDa, were successfully made using the casting method. Results of the scanning electron microscopy micrographs showed that the two biopolymers were compatible. Moreover, the mechanical properties analyses revealed that films based on the smooth-hound viscera proteins possessed higher tensile strength (TS) but lower elongation at break (EAB), compared to the gelatin film, where Bl-F were mechanically stronger and less deformable than Bi-F. Based on the differential scanning calorimetry analyses, Bl-F have the highest glass transition temperature (Tg) (63–67 °C), confirming their glassy character at room conditions. In addition, Bl-F were found more effective on preventing moisture transfer, in a 30–84% relative humidity differential, than Bi-F, though the SHP addition slightly reduced the water vapor barrier efficiency. The analysis of surface properties demonstrated that all films possessed hydrophobic surface. Interestingly, SHP and SP addition greatly enhanced the antioxidant property of the films allowing them to be successfully used for food industries as bioactive packaging materials.
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•Composite films were made based on smooth-hound gel and gelatin.•Surface property and water vapor permeability were affected by the type of additive.•All films showed interesting mechanical and thermal properties.•Peptides or polysaccharides addition improved the antioxidant properties of films.
The objective of this work was to better display the effect of electron beam accelerator doses (0, 20, 40 and 60 kGy) on structural, mechanical and barrier properties of edible lightly plasticized ...chitosan-fish gelatin blend film. From Electron Spin Resonance (ESR), signal at 3500 G for blend film was identified as free radical formation during irradiation, which might introduce intermolecular cross-linking into the polymer matrix, thus affecting structural properties. Tensile Strength (TS) for gelatin film significantly increased with growing irradiation doses (improved by 30% for 60 kGy), but the TS of chitosan and blend films were not significantly affected. On the contrary, irradiation significantly reduced elongation at break (%E) for chitosan and blend film up to 50% whereas it twice increased the Young modulus. Moisture barrier efficiency (30–84% RH gradient) of blend films was slightly improved after irradiation. Oxygen permeability also decreased after 60 kGy irradiation treatment, for both chitosan and blend films. Surface hydrophobicity tended to decrease after irradiation. From Fourier Transform Infra-Red (FTIR) spectra, some noticeable differences were observed after irradiation, in the relative intensity and position of bands in the region between 3600 and 2800 cm−1 and between 1700 and 1500 cm−1. UV-vis analysis shows that all films displayed an absorbance peak between 280 and 385 nm. These peaks are shifted toward higher wavelengths after irradiation This clearly showed some modifications in the interactions (hydrogen bonds, amide groups) between polymer chains induced by the irradiation.
Effect of irradiation dose on water vapour permeability of films based on chitosan and fish-gelatin. Display omitted
•Polyelectrolyte complexes of chitosan and gelatin for film making and exposed to electron beam irradiation.•Improvement of barrier and mechanical properties after irradiation.•Microstructure becomes denser and surface properties tends to be more hydrophilic due to irradiation.•FTIR and UV analysis display the amide group and tyrosine involvement in network organization during irradiation.
•CSG and CSPI blend films were prepared.•Physicochemical and antioxidant properties of films were evaluated.•Blend films displayed high antioxidant activities with different potentialities.•CSG and ...CSPI were totally miscible.•Cuttlefish skin can serve as a potential source of bioactive polymers.
In the present study, cuttlefish skin gelatin (CSG) and protein isolate (CSPI) blend films were prepared and their physicochemical and antioxidant properties were characterized. CSG (4%, w/v) was blended with CSPI (3%, w/v) at different ratios and 15% of glycerol (w/w, plasticizer/polymer dry matter). Results showed that increasing of CSPI content induced lower lightness but higher redness, yellowness and color difference values compared to CSG film. In addition, CSPI film had the lowest tensile strength (TS) and elongation at break (EAB) values. The FTIR spectra of blend films showed a shift in the position of peaks related to the amide-I group, suggesting that they were involved in the interaction between the biopolymers. The structural properties evaluated by DSC showed a total miscibility between both polymers. This result was also confirmed by the SEM study, revealing a compact and homogenous structure in the blend films. Moreover, the water contact angle decreased in blend films, especially for those having higher proportion of CSPI. The antioxidant activity of films was markedly favored by the CSPI incorporation. Therefore, CSPI addition into gelatin matrix allowed to improve the blend films properties, mainly governed by the CSG/CSPI ratio.
In order to improve the quality of food and to extend their shelf life, a new generation of active edible films is being especially intended after the incorporation of organic acids, enzymes, ...antimicrobial proteins, phenolic compounds, or other functional ingredients such as probiotics, flavors, vitamins and nutraceuticals. These active compounds have different mechanisms of action related to their structure, their concentration, the nature of micro-organism targeted, the process of encapsulation or incorporation in the biopolymer film-networks. The application of the active films by direct contact or indirect contact via the head space also affects the bioactivity of these compounds. This article critically reviews the published work on active edible-films and their applications for food preservation. The classes of active compounds and their action mechanisms are firstly discussed. Then, an extended overview on their effect on model food (simulants) or on real food during storage was also addressed. Edible films offer two main advantages over the direct incorporation of the antimicrobial or antioxidant agents into the bulk food: 1) to control the diffusion of active compounds at the surface of the food and 2) to reduce the amount of preservatives added in the food.
Nowadays, a new generation of edible films is being especially designed for incorporating antimicrobials, antioxidants, enzymes or functional ingredients. Edible films made from natural biopolymers ...become the focus of many research works as an alternative to synthetic food packaging due to their edibility, biodegradability and compostability as well as to their use as active packaging. Active compounds incorporated in edible films could protect foods against deterioration during storage and therefore extend their shelf life. These active films were mainly studied for the bioactivity, as antimicrobial or antioxidant. However, they could also improve the structure and the physicochemical properties of films through chemical linkage with reactive groups of the polymer chains for instance. Moreover, changing the film structure under cross-linking reaction may increase the cohesion between polymer chains and active compounds, and therefore their retention in the polymer network to better control their release.
This manuscript provides an overview on the effect of bio-active compounds incorporation on the film structure and functional properties. Depending on their structure, concentration, reactive groups,.., active compounds can act as plasticizer, but also as anti-plasticizer or cross-linking agents in the biopolymer matrix, and can thus ameliorate the water vapour and gas permeability. Therefore, the retention of bioactive compounds in the polymer network and their release can be better controlled. They can also provide a negative plasticizing effect on the film structure. Hence, the improvement of edible active film functionalities has been investigated to achieve suitable applications on foods.
Hydrocolloid-based films containing natural phenolic antioxidants (gallic and trans-cinnamic acids at 5% w/wt of polymers) embedded in a gelatin/chitosan matrix were designed as sustainable active ...packaging. This work deals with characterizing the release mechanisms of the phenolic acids from the films immersed into food simulants (sugar or polyol solutions) having different water activities and viscosities. The films containing gallic acid exhibited higher antioxidant activities than the trans-cinnamic acid films. The use of sucrose or glycerol to reduce the water activity (aw) both decreases the iron chelating power (antioxidant) and the E Coli growth (antimicrobial). Interactions involved between macromolecules (chitosan and gelatin) and phenolic compounds influence the release kinetic parameters (diffusivity, convection and partition coefficients) that were studied according to the nature of solute, the water activity and the viscosity of the release media. Thermal analysis (TGA and DSC) revealed a plasticization by both sucrose and glycerol, which entered the film.
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•Sucrose or glycerol content in food simulants affect release and bioactivity of phenolic acids.•A bactericidal / bacteriostatic effect of gallic acid films against E.coli.•Release rate and water activity influence the antimicrobial activity.•Diffusion and convection coefficients of the phenolic acids correlated to the viscosity of release medium.•Partition coefficient of phenolic acid influenced by the water activity and solute nature of the release medium.
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•Active chitosan-fish gelatin film containing natural antioxidants.•Improvement of films mechanical and barrier properties after antioxidants addition.•Charge-charge interactions with ...the ammonium groups of gelatin and/or chitosan for phenolic acids.•The effective diffusion coefficient of tyrosol was 170 times greater than phenolic acids.•Antioxidant activity can be limited/influenced by the release kinetic.
This work deals with the study of the release kinetics of some natural antioxidants (ferulic acid, caffeic acid and tyrosol) from chitosan-fish gelatin edible films immersed ethanol at 96%, as well as the kinetics of their antioxidant activity using the DPPH assay. The aim was to determine how film functional properties influence the release kinetic and antioxidant activity. The addition of antioxidants to chitosan-fish gelatin matrix decreased the water vapour permeability by more than 30%. The tensile strength (TS) increased up to 50% after the incorporation of antioxidants. Some molecular interactions between polymer chains and antioxidants were confirmed by FTIR where spectra displayed a shift of the amide-III peak. Films containing caffeic acid or a caffeic-ferulic acid mixture exhibited the highest radical scavenging activity, leading to a 90% antioxidant activity at equilibrium but the release rate controlled the efficacy of the system.
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•Fish gelatin film irradiated by electron beam accelerator.•Electron spin resonance analysis reveals the formation of free radical species after irradiation.•No modification of the ...crystallinity after irradiation.•Enhancement of thermal and mechanical properties of the film.•Slight increase in surface polarity as well as water vapour permeability.
The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino acids. No modification of the crystallinity of the film is observed. These findings suggest that if structure changes, it only occurs in the amorphous phase of the gelatin matrix. It is also observed that irradiation enhances the thermal stability of the gelatin film, by increasing the glass transition temperature and the degradation temperature.
This study investigates the effect of Maillard reactions (MR) on the physico-chemical and biological properties of fish gelatin based edible films. Glucose was incorporated in gelatin film forming ...solutions at different glucose/lysine molar ratios: 0.5/1.0, 1.0/1.0 and 5.0/1.0. The MR was then induced by heating films at 90 °C for 24 h in dry conditions. Color changes and browning index measurements were used to pursue the MR kinetic. Results showed that the development of MR products was dependent on the glucose content and on the reaction time. Mechanical and thermal properties of treated films displayed an increase in tensile strength, elongation at break and glass transition temperature with the glucose addition and heating time. In addition, barrier properties against UV light and water resistance (water solubility and water contact angle measurements) increased due to the gelatin-glucose interactions generated at high temperature. The in vitro antioxidant activity of fish gelatin films modified by MR was studied by using DPPH free radical scavenging, total antioxidant activity and the reducing power. The antioxidant activity was significantly enhanced with mainly the glucose content and, in a less extent, with the reaction time. Consequently, fish-gelatin based films cross-linked through the Maillard reactions pathway are promising for food edible packaging materials to protect products toward oxidation.
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•Generation of bioactive compounds by Maillard reaction in Fish gelatin edible films.•Glucose/lysine ratio influenced significantly the film properties.•Physical-chemical properties enhanced by Maillard reaction due to favored crosslinking.•Fish gelatin films exhibit significant antioxidant properties (up to x5) after Maillard reaction treatment.
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