Active Edible Films Research Articles

Shelf life extension of refrigerated breaded hake medallions packed into active edible fish gelatin films

Fish consumption has increased in recent years. However, fish meat is highly perishable, which demonstrates the need for technologies to preserve its quality. Edible films might provide an alternative to extend the shelf life of fish. The goal of this study was to evaluate the efficiency of edible fish gelatin films added with carvacrol (blended: FG‐0.6CRV and grafted: FG/CRV‐g‐FG) on the quality retention of commercially available prefried breaded hake medallions (BHMs). Samples of BHM were wrapped into films, heat sealed, and stored at −4 ± 1 °C for 49 days. Free carvacrol gelatin films and the unwrapped medallions were used as controls. After predetermined periods of time, samples were analysed in terms of microbiological and physicochemical properties. Overall the storage period, the total volatile basic nitrogen value (TVBN) and the total psychrotrophic bacteria counts (TPC) were significantly lesser in BHM wrapped in FG‐0.6CRV than in the other samples. The total oxidation index (TOI), peroxide value (PV), and p‐anisidine value (AV) were reduced by 18%, 30%, and 16%, respectively, compared with controls. FG/CRV‐g‐FG film was not efficient to reduce the microbial spoilage or the oxidation, probably due to the retention of CRV into the matrix avoiding its migration towards the foodstuff, proving the importance of checking the films functionality in real food systems. Sensory evaluation of fried samples wrapped in FG‐0.6CRV was also performed. The results indicate that the medallions can be directly cooked and consumed without removing the packaging with a good acceptance by the consumer.

Preparation and antioxidant activity of sodium alginate and carboxymethyl cellulose edible films with epigallocatechin gallate

The active edible films were prepared by incorporating epigallocatechin gallate (EGCG) into sodium alginate (SA) and carboxymethyl cellulose (CMC). The effects of EGCG addition on the physical and morphological properties of SA-CMC films were evaluated. Meanwhile, the release characteristics of EGCG from edible films and its antioxidant activity in fat food simulant (95% ethanol) were also detected. The results showed that the addition of EGCG could improve the tensile strength (TS) of edible films and reduce their elongation at break (E). Especially, the color of edible film added with EGCG deepened and the transmittance decreased. Scanning electron microscopy (SEM) images displayed that the films were dense and compact with a little roughness. Fourier transform infrared spectroscopy (FTIR) analysis indicated that the incorporation of EGCG into SA-CMC caused interactions occurring between SA-CMC and EGCG. In addition, the release and DPPH radical scavenging assay of incorporating EGCG in SA-CMC films showed that the obtained SA-CMC films with high EGCG content could release EGCG slowly and had strong antioxidant activity in fatty foods. Thus, incorporating EGCG into SA-CMC film was an effective way in order to develop active and environmental friendly packing materials for food industry.

Chickpea flour‐based biofilms containing gallic acid to be used as active edible films

ABSTRACTChickpea is an easily accessible nutritious legume. Besides, gallic acid is a widespread phenolic found in various plants. In this study, it is aimed to investigate the effects of pH (9 and 11), glycerol concentration (1 and 3% w/v of film solution) and gallic acid concentration (5 and 10% w/w of total solid) on color, opacity, mechanical strength, water vapor permeability (WVP), microstructure, chemical characteristic, antioxidant activity, and phenolic content of films. At pH 11, films are stronger, darker and have higher antioxidant activity. Higher glycerol concentration makes the films more flexible but less strong and more hydrophilic. Higher gallic acid concentration makes great contribution to the films by decreasing WVP but by increasing opacity, antioxidant activity, phenolic content, lightness, and elongation. Film containing glycerol of 1% and gallic acid of 10% and prepared at pH 11 was found to be a great combination for obtaining antioxidant rich edible composite films.HIGHLIGHTS Chickpea flour‐based active films were successfully obtained with addition of gallic acid. Higher gallic acid concentration decreased WVP, increased opacity, antioxidant activity, phenolic content, lightness, and elongation. Higher pH provided stronger mechanical properties, low lightness, and higher antioxidant activity. Lower glycerol concentration resulted lower WVP and stronger tensile properties. Chickpea flour‐based active films at pH 11 with 1% glycerol and 10% gallic acid can be used as active packaging material in especially highly oxidative food products. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47704.

Active edible films of methylcellulose with extracts of green apple (Granny Smith) skin

The aim a present study was developed methylcellulose (MC) active edible films with extracts of green apple skin, as model systems of edible coating. Active edible films were developed by incorporation of ethanolic extract of freeze-dried apple skin (EEFD) and aqueous extract of apple skin (AES) at 10, 20 and 25% (v/v) concentrations. Analysis of thermal, mechanical and functional properties was carried out. Results showed that incorporation of green apple skin extracts into MC films contribute to total phenolic content and antioxidant properties. Addition of green apple skin extracts generated shifts toward lower glass transition temperature values regarding MC films without extracts. A lower tensile strength and increased elongation at break in MC-AES films were observed. Mechanical properties of MC-EEFD films were less affected by the increase in extract concentration due to absence of the plasticizing effect of sugars present in AES. The methylcellulose films are important for actives edibles coatings with applications in the food industry.

Characterization of Active Edible Films based on Citral Essential Oil, Alginate and Pectin.

Thermal, structural and physico-chemical properties of different composite edible films based on alginate and pectin with the addition of citral essential oil (citral EO) as an agent to improve barrier properties, were investigated. The obtained films were clear and transparent, with a yellow hue that increased with citral EO addition. All the films displayed good thermal stability up to 160 °C, with a slight improvement observed by increasing the amount of citral EO in the composites. Gas transmission rate (GTR) strongly depended on the polymer structure, gas type and temperature, with improvement in barrier performance for composite samples. Also, citral EO did not exert any weakening action on the tensile behavior. On the contrary, an increase of the elastic modulus and of the tensile strength was observed. Lastly, water contact angle measurements demonstrated the dependence of the film wettability on the content of citral EO.

Physical properties and antioxidant activity of gelatin-sodium alginate edible films with tea polyphenols

Active edible films were prepared by incorporating tea polyphenols (TP) into gelatin and sodium alginate. The effects of 0.4%–2.0% TP (w/w, TP/gelatin) on physical, antioxidant, and morphological properties of gelatin-sodium alginate films were evaluated. Tensile strength (Ts), contact angle (CA), and cross-linking degree showed an enhanced trend as TP concentration in the film increased, whereas elongation at break (EAB) and water vapor permeability (WVP) possessed a decline trend. The light transmittance of the film was decreased by the incorporation of TP. Antioxidant capacity was improved by increasing TP content in the films. For DPPH and ABTS radical, the films with 2.0% TP possessed the highest values of 90.62 ± 2.48% and 53.36 ± 1.06 Trolox (mg Trolox equivalent/g film), respectively. Fourier transform infrared spectroscopy analyses (FTIR) indicated the interactions existed between gelatin‑sodium alginate and TP. Smooth and continuous surface and dense internal structure of the films with TP were observed by scanning electron microscopy (SEM). Thus, incorporating TP into gelatin and sodium alginate film solution was an effective method in order to improve physical properties and antioxidant activity of the films. Gelatin-sodium alginate films with TP could be used as an edible film for food packaging applications.

Antiviral and antioxidant properties of active alginate edible films containing phenolic extracts

In this work, novel active edible films having antiviral activity were developed through the solvent casting method. Emulsified edible films were prepared by adding lipids into alginate films in order to improve their water vapour permeability. In addition, two natural extracts rich in phenolic compounds, specifically a green tea extract (GTE) and a grape seed extract (GSE) were used as active agents. Interestingly, incorporating GTE or GSE within the biopolymer matrix, the films exhibited significant antiviral activity against murine norovirus (MNV) and hepatitis A virus (HAV) since ∼2 log reduction were recorded for the 0.75 g extract/g alginate in the film, being GTE more efficient than GSE. Furthermore, the incorporation of phenolic compounds imparted antioxidant capacity to the active films, showing 14.79 ± 0.25 and 3.50 ± 0.25 mM Trolox⋅ g extract in the film−1 for 0.75 GTE and 0.75 GSE films, respectively. It was also found that water barrier efficiency improved upon addition of the highest amount of GTE or GSE (1:0.75 alginate:extract ratio) which was ascribed to molecular interactions between the films' components, as demonstrated by infrared spectroscopy assays.These results reveal the potential of these active films, mainly the ones containing GTE, to improve food quality and safety.

Alginate edible films containing microencapsulated lemongrass oil or citral: effect of encapsulating agent and storage time on physical and antimicrobial properties.

Active edible films have been proposed as an alternative to extend shelf life of fresh foods. Most essential oils have antimicrobial properties; however, storage conditions could reduce their activity. To avoid this effect the essential oil (EO) can be microencapsulated prior to film casting. The aim of this study was to determine the effects of the type of encapsulating agent (EA), type of EO and storage time on physical properties and antimicrobial activity of alginate-based films against Escherichia coli ATCC 25922. Trehalose (TH), Capsul® (CAP) and Tween 20 (Tw20) were used as EA. Lemongrass essential oil (LMO) and citral were used as active agents. The results showed that the type of EA affected the stability of the film forming-emulsions as well as the changes in opacity and colour of the films during storage but not the antimicrobial activity of them. Both microencapsulated EOs showed a prolonged release from the alginate films during the 28days of storage. Trehalose was selected to encapsulate both active compounds because the films made with this microencapsulated EA showed the greatest physical stability and the lowest color variation among all the films studied.

Characterization of novel basil-seed gum active edible films and coatings containing oregano essential oil

Basil seed gum (BSG) edible films containing oregano essential oil (OEO) (1–6%) were fabricated and evaluated for antibacterial activity against E. coli, S. Typhimurium, P. aeruginosa, S. aureus and B. cereus, as well as antioxidant activity, film thickness, moisture content, transparency, swelling index, contact angle and water vapor permeability (WVP). The thickness of BSG based film was recorded as 0.06 mm; the increase in OEO concentration did not change the thickness significantly (p > 0.05). The WVP was decreased significantly by incorporation of OEO while the moisture content, contact angle, transparency and swelling index (p < 0.05) of edible films were increased. All films containing 2–6% OEO presented a significant antibacterial activity against the examined pathogens. The DPPH and ABTS radical scavenging activities and ferric reducing ability of BSG films were enhanced considerably with increasing OEO concentration. According to results, the fabricated edible films with BSG and OEO can be considered for further approaching as an edible food packaging.

Development and application of edible film of active potato starch to extend mini panettone shelf life

Physicochemical properties may determine quality attributes and consumer acceptability of mini panettones. To reduce the conservatives added in food, this study developed active edible films of potato starch, inverted sugar and sucrose to coat mini panettones. All three variables significantly affected (p < 0.05) moisture, aw, hardness and elasticity of panettones. The selected formulation (46 g/kg starch, 14 g/kg inverted sugar and 7 g/kg sucrose) was added to potassium sorbate (1 g/kg), citric acid (10 g/kg) and both additives (1 g/kg sorbate + 10 g/kg citric acid and 0.5 g/kg sorbate + 5 g/kg citric acid). From 16 to 24 days (35 °C/60% RH), panettones without coating and without additives (controls) showed growth of mold/yeast; while with both additives coating, fungal growth was observed from 40 days. When using potassium sorbate, mold/yeast was not detected until 48 days. During storage, there was reduced water activity, moisture, elasticity and cohesiveness of panettones with additives, while the reverse occurred in controls. The incorporation of food-graded antimicrobial compounds in the packaging films of potato starch coatings in concentrations lower than those normally used for mini panettones increased up to 130% their shelf life and may contribute to product loss reduction during storage.

Active edible films: Current state and future trends

ABSTRACTActive edible films represent one of the current and future trends in the development of new polymers for selected applications, particularly food packaging. Some biopolymers show excellent performance as carriers for active compounds extracted from natural sources and are able to be released at a controlled rate to packaged food. In this review we aim to present, in a comprehensive way, the most recent advances and updates in this subject, where much research is currently ongoing and new studies are reported very often. This review focuses on innovative biopolymer matrices, their processing to obtain edible active films, and present and future applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42631.

Bio-based composite edible films containing Origanumvulgare L. essential oil

Biocomposite films based on fish gelatin and chitosan containing Origanumvulgare L. essential oil (OEO) at 0.4, 0.8, and 1.2% (w/v) were prepared by a solvent casting method and their physicochemical and antimicrobial properties were examined. The results showed that the incorporation of OEO caused a significant decrease (p<0.05) in tensile strength (TS) and elastic modulus (EM), although no significant change was observed in elongation-at-break (EAB). Water vapor permeability (WVP) and solubility of films containing OEO increased as the amount of oil increased (p<0.05). Oregano essential oil-loaded films displayed superior barrier capability to ultraviolet light. Fourier transforms infrared (FTIR) spectra indicated that the interaction between polymer matrix and essential oil was occurred. The properties of the films were related with their microstructure, which was observed by scanning electron microscopy (SEM). Atomic force microscopy (AFM) images showed that the surface roughness of the films was influenced by the inclusion of oil. OEO-incorporated films also exhibited higher antimicrobial activity against the gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes), and lower for gram-negative bacteria (Salmonella enteritidis and Escherichia coli). This study showed that OEO has the potential to prepare active edible films.

Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol

Active edible films were prepared by adding carvacrol into sodium caseinate (SC) and calcium caseinate (CC) matrices plasticized with two different glycerol concentrations (25 and 35wt%) prepared by solvent casting. Functional characterisation of these bio-films was carried out by determination of some of their physico-chemical properties, such as colour, transparency, oxygen barrier, wettability, dye permeation properties and antibacterial effectiveness against Gram negative and Gram positive bacteria. All films exhibited good performance in terms of optical properties in the CIELab space showing high transparency. Carvacrol was able to reduce CC oxygen permeability and slightly increased the surface hydrophobicity. Dye diffusion experiments were performed to evaluate permeation properties. The diffusion of dye through films revealed that SC was more permeable than CC. The agar diffusion method was used for the evaluation of the films antimicrobial effectiveness against Escherichia coli and Staphylococcus aureus. Both SC and CC edible films with carvacrol showed inhibitory effects on both bacteria.

How composition and process parameters affect volatile active compounds in biopolymer films

Active edible films based on chitosan and containing an active aroma compound have been investigated. The influence of the composition of the film forming solution (solvent, plasticizers, nanoparticles, emulsifiers and aroma traps) and process parameters (temperature and viscosity) on drying kinetics, water content, colour, aroma compound retention and partition coefficient was studied. Solvent evaporation rate was increased by addition of ethanol. Water evaporation was delayed by glycerol. The aroma retention during film drying was directly related to the water content. The drying temperature had opposite influences according to the composition of the solvent and additives. Increasing temperature from 20 to 100 °C could increase 3 times the retention of aroma compounds. The viscosity of film forming solutions was strongly increased by biopolymer content and glycerol but reduced by carvacrol and ethanol. To improve carvacrol retention, the most efficient additive was gum arabic, followed by glycerol whereas the effect of nanoclays or emulsifiers remained weak.

Antimicrobial effectiveness of oregano and sage essential oils incorporated into whey protein films or cellulose-based filter paper

In this study the antimicrobial effectiveness of oregano and sage essential oils (EOs) incorporated into two different matrices, whey protein isolate (WPI) and cellulose-based filter paper, was analysed. Antimicrobial properties of WPI-based films containing oregano and sage EOs were tested against Listeria innocua, Staphylococcus aureus and Salmonella enteritidis. Oregano EO showed antimicrobial activity against all three micro-organisms. The highest inhibition zones were against L. innocua. However, sage EO did not show antimicrobial activity against any of the micro-organisms. Antimicrobial activity was confirmed for both EOs using cellulose-based filter paper as supporting matrix, although it was significantly more intense for oregano EO. Inhibition surfaces were significantly greater when compared with those of the WPI films. This finding is likely due to the higher porosity and diffusivity of the active compounds in the filter paper. The interactions between the EOs and the films have a critical effect on the diffusivity of the active compounds and therefore on the final antimicrobial activity. As a result, to obtain active edible films, it is necessary to find the equilibrium point between the nature and concentration of the active compounds in the EO and the formulation of the film.

Mass transport properties of tapioca-based active edible films

The release of potassium sorbate from tapioca starch-based edible films with glycerol as plasticizer was studied and modeled. Tapioca importance as a source of starch is growing rapidly, especially because its price in the world market is low when compared to starches from other sources. A semi-empirical approach was proposed to describe the diffusion of water molecules into the polymeric film, the counter diffusion of the antimicrobial compound and the polymeric matrix swelling kinetic. Despite the simplicity of the proposed model, it successfully fitted the experimental data. From the obtained results it was observed that casting technique, producing films with high amorphous degree, determined a greater contribution of matrix relaxation to sorbate release. The pH of the receiving media contributed slightly to antimicrobial release and its effects seem to be related to the influence of this variable on antimicrobial solubility.