Lower Water Vapor Permeability Values Research Articles

Agro-Industrial Protein Waste and Co-Products Valorization for the Development of Bioplastics: Thermoprocessing and Characterization of Feather Keratin/Gliadin Blends.

Biopolymers based on plant and animal proteins are interesting alternatives in the development of films with future prospects as food packaging. Considering that in recent years there has been an increasing interest in the valorization of agro-industrial residues and by-products and that the blending of polymers can lead to materials with improved properties, in this work, keratin-rich feather fibers and gliadins were blended at different ratios in order to develop sustainable and biodegradable films. Control gliadin G100, feather F100 films, and their blends at 3:1 (G75F25), 2:2 (G50F50), and 1:3 (G25F75) ratios were successfully developed through thermoprocessing. The physical properties were differentiated as a function of the concentration of both polymeric matrices. Although gliadins showed higher hydrophilicity as confirmed by their highest swelling degree, films with high gliadin ratios exhibited lower water vapor permeability values at low and medium relative humidities. On the other hand, the feather fiber-based films displayed the highest Young's modulus values and provided an oxygen barrier to the blends, principally at the highest relative humidity. In conclusion, the blend of these protein-based polymers at different ratio resulted in interesting composites whose physical properties could be adjusted.

Development of composite film based on collagen and phenolic acid-grafted chitosan for food packaging

Collagen, a fibrous protein with triple-helical structure, is a good film-forming substrate for food packaging films because collagen films show advantages of biodegradability, high mechanical strength and good water resistance. However, collagen films lack functional activities, which may limit their applications in the field of active packaging. In this work, phenolic acid-grafted-chitosan was blended with collagen to improve the antioxidant and antimicrobial activities of collagen films. Gallic acid (GA), ferulic acid (FA) and caffeic acid (CA) were respectively grafted onto chitosan, and the physical properties and functional activities of the collagen/phenolic acids-g-chitosan (CGC, CFC and CCC) films were compared. The prepared films presented varying degrees of yellow color, and exhibited significantly improved UV light blocking capacity, antioxidant and antimicrobial properties due to the function of phenolic acid. Moreover, compared with collagen/chitosan (CC) film, CGC, CFC and CCC films showed higher mechanical strength (69.08–73.79 MPa), higher thermal denaturation temperature (69.4–71.2 °C), and lower water vapor permeability values (2.64–2.98 × 10−12 g m−1 s−1 Pa−1). The properties of collagen/ phenolic acids-g-chitosan films were greatly affected by the type of phenolic acid grafted. CGC film had the best antioxidant property as well as the best mechanical property, thermostability, UV light and water vapor blocking capacity.

Efekat šelak smole na osobine zeinskog filma

In this paper, zein-based films with the addition of shellac were synthesized by lamination on the existing dry zein film (L samples) and by adding shellac alcohol solution during the synthesis of zein film in a ratio of 50-50 by casting process (M samples). Zein films without the addition of shellac were designated as control samples. Physico-chemical (thickness, moisture content and solubility), mechanical (tensile strength and elongation at break) and barrier characteristics (water vapor permeability) were examined for all samples. The resulting films were transparent, glossy, light yellow (control) to ocher (samples with shellac), flexible, and non-sticky. The results showed significantly higher values of elongation at the break of the samples with shellac (11.49% for M and 18.99% for L) compared to the control (7.14%). Significantly lower water vapor permeability values were found, 10.04 g/(m²ꞏh) for L, and 18.41 g/(m²ꞏ h) for M, compared to the control pure zein film (40.33 g/(m² ꞏh)).

Morphological and Mechanical Characterization of Films Incorporating Porphyran Extracted from Porphyra Dioica

This paper studies the effects of glycerol plasticizers and/or alginate, pectin, and carboxymethylcellulose polysaccharides on the mechanical and physical properties of porphyran-based films to evaluate the films’ ability to be used as food packaging. Films were characterized in terms of their composition, microstructural and morphological features, thermal properties, water interaction, and mechanical performance. All films are homogeneous, transparent, and slightly brownish in color. The structures are amorphous and crosslinked, showing the films’ thermoset nature. Moisture content and water solubility depend on the second polysaccharide added to the porphyran, but they both increase with the addition of glycerol to the formulations; water vapor permeability is strongly affected by the second polysaccharide in the formulation. The films display stiff and brittle mechanical behavior, but ductility increases significantly in formulations containing glycerol plasticizers. The barrier and mechanical performance values of the materials produced were found to be lower than those reported for commercial food packaging. The formulations containing glycerol displayed lower water vapor permeability values, ranging from 2.98 for porphyran/carboxymethylcellulose/glycerol to 6.65 mm·g·d−1·m−2·kPa−1 for porphyran/alginate/glycerol films. All films, except porphyran/glycerol and porphyran/alginate/glycerol, had ultimate tensile strengths above 10 MPa—the threshold value that ensures that a package is ductile enough to withstand handling and forming operations. Furthermore, the porphyran/pectin/glycerol and porphyran/carboxymethylcellulose/glycerol films displayed sufficiently high ductility values of 2.94 and 3.10%, respectively. These results indicate that the studied porphyran/pectin/glycerol and porphyran/carboxymethylcellulose/glycerol formulations have a combination of physical and mechanical properties that ensure adequate film integrity and function through the complete food packaging supply chain. The results here reported represent an opportunity to extend the scope of porphyran films to applications in the dry food packaging industry.

Properties of chitosan–papain biopolymers reinforced with cellulose nanofibers

There is currently a strong tendency toward the use of biodegradable packaging produced from biopolymers containing active substances. Papain can be used in active packaging. The aim of this paper was to study the effect of cellulose nanofibers (CNF) and papain on the structural, mechanical, and thermal properties of films of chitosan. The experiment was performed with CNF and papain concentrations ranging from 0%–8% and 0%–10%, respectively. The CNF increased the water solubility of films. Lower water vapor permeability values were observed for the films with 4% CNF and papain concentrations up to 6%. Films reinforced with CNF and without papain were rigid and more resistant. Films incorporated with papain and with or without CNF reduced the tensile strength, the percentage of elongation, and the resistance to perforation. The addition of papain improved thermal stability. The films with 2% papain and 4% CNF presented the best results for the parameters studied. Practical applications There is a tendency toward the use of biodegradable packaging produced from biopolymers containing active substances. Papain can be used in active packaging. The aim of this studied was to analyze the properties of chitosan films with cellulose nanofibers (CNF) and papain. The incorporation of papain reduced the mechanical properties of the films with and without CNF and improved thermal stability. The addition of papain allowed to obtain films with good properties that allow them to be applied as active films.

Chitosan Films Obtained from Brachystola magna (Girard) and Its Evaluation on Quality Attributes in Sausages during Storage.

High molecular weight chitosan (≈322 kDa) was obtained from chitin isolated from Brachystola magna (Girard) to produced biodegradable films. Their physicochemical, mechanical and water vapor permeability (WVP) properties were compared against commercial chitosan films with different molecular weights. Brachystola magna chitosan films (CFBM) exhibited similar physicochemical and mechanical characteristics to those of commercial chitosans. The CFBM films presented lower WVP values (10.01 × 10−11 g/m s Pa) than commercial chitosans films (from 16.06 × 10−11 to 64.30 × 10−11 g/m s Pa). Frankfurt-type sausages were covered with chitosan films and stored in refrigerated conditions (4 °C). Their quality attributes (color, weight loss, pH, moisture, texture and lipid oxidation) were evaluated at 0, 5, 10, 15 and 20 days. Sausages covered with CFMB films presented the lowest weight loss (from 1.24% to 2.38%). A higher increase in hardness (from 22.32 N to 30.63 N) was observed in sausages covered with CFMB films. Compared with other films and the control (uncovered sausages), CFMB films delay pH reduction. Moreover, this film presents the lower lipid oxidation level (0.10 malonaldehyde mg/sample kg). Thus, chitosan of B. magna could be a good alternative as packaging material for meat products with high-fat content.

Development of Chitosan and Polycaprolactone Based Trilayer Biocomposite Films for Food Packaging Applications

Chitosan (CH) films were obtained by casting method and sandwiched between 2 layers of polycaprolactone (PCL), which were formed by compression molding, to form trilayers. CH films were also incorporated with grape seed extract (G) (15%, w/w) and/or nanocellulose (N) (1-5%, w/w). The tensile properties, transmittance, opacity, water vapor permeability (WVP), antimicrobial activity, and release behavior of trilayers were determined. The elastic modulus (EM) of trilayer films were not significantly affected by the N content, while higher N concentrations resulted in higher tensile strength (TS) values. The incorporation of G led to higher elongation values and resulted in lower EM and TS values. Film samples, including N, presented lower WVP values, whereas higher WVP and water solubility values were obtained with G inclusion (p<0.05). L* and transmittance values increased with the increasing N content while the opacity values decreased (p<0.05). Furthermore, films added G showed significantly higher a* and b* values. The addition of N caused slower release of G from CH films through the selected food simulants. The obtained trilayer films also inhibited selected main pathogenic bacteria. The fabrication of PCL and CH films in the trilayer form enhanced the properties of CH and made these films more appropriate for food packaging.

On the Use of Persian Gum for the Development of Antiviral Edible Coatings against Murine Norovirus of Interest in Blueberries

In the last decades, berries have been identified as important vehicles for the transmission of foodborne viruses and different strategies are being explored to eliminate or reduce viral contamination in these fruits. The aim of this work was to develop novel edible coatings with antiviral properties for inactivating and reducing murine norovirus (MNV). Firstly, the effect of gelatin (G) addition on Persian gum (PG) films was studied in terms of microstructural, mechanical, optical, and water barrier properties. The following PG:G ratios were considered: 100:0, 75:25, 50:50, 25:75, and 0:100. Microstructure analysis revealed the compatibility of both hydrocolloids since no phase separation was observed. The addition of G to PG films provided stiffer and more deformable films than pure PG, with lower water vapor permeability values. Specifically, films prepared with 50:50 PG:G ratio presented better mechanical and barrier performance. Interestingly, pure PG showed antiviral activity on murine norovirus, probably due to the presence of some impurities (mainly tannins). Adding allyl isothiocyanate (AITC) enhanced the PG antiviral activity at refrigerated temperatures in blueberries, not being affected by the AITC concentration. This effect was not observed at ambient temperature, probably due to the volatilization of AITC.

Influence of Different Commercial Modified Cassava Starches on the Physicochemical Properties of Thermoplastic Edible Films Obtained by Flat‐Die Extrusion

AbstractStarch constitutes a promising resource for biodegradable packaging, but it presents several processing drawbacks when using conventional industrial equipment, such as flat‐die extrusion. This work demonstrates that the replacement of native cassava starch (NS) with commercial hydrolyzed (HS) or carboxymethyl (CMS) starches diminishes the amount of energy required to process starch granules into thermoplastic films by extrusion. Homogeneous films with starch‐glycerol interaction improvements are obtained when using HS or CMS instead of NS. HS films exhibit the lowest crystallinity and the highest susceptibility to water among the studied systems. Likewise, CMS films maximize Vh crystalline structure fraction and present higher Young's modulus and stress at break, and lower water vapor permeability values. In order to combine the positive properties and to overcome the limitations of each modified starch, blend films from HS:CMS (50:50 wt%) are also developed and investigated. Phase separation is observed in this system, and there are no improvements in the overall properties. The results of this investigation show that employing commercial CMS, even in very low carboxymethylation degree represents a successful strategy to improve mechanical and barrier properties of flat‐die extruded films, while HS can be used to obtain water‐soluble films for specific applications.

Innovative Antimicrobial Chitosan/ZnO/Ag NPs/Citronella Essential Oil Nanocomposite-Potential Coating for Grapes.

New packaging materials based on biopolymers are gaining increasing attention due to many advantages like biodegradability or existence of renewable sources. Grouping more antimicrobials agents in the same packaging can create a synergic effect, resulting in either a better antimicrobial activity against a wider spectrum of spoilage agents or a lower required quantity of antimicrobials. In the present work, we obtained a biodegradable antimicrobial film that can be used as packaging material for food. Films based on chitosan as biodegradable polymer, with ZnO and Ag nanoparticles as filler/antimicrobial agents were fabricated by a casting method. The nanoparticles were loaded with citronella essential oil (CEO) in order to enhance the antimicrobial activity of the nanocomposite films. The tests made on Gram-positive, Gram-negative, and fungal strains indicated a broad-spectrum antimicrobial activity, with inhibition diameters of over 30 mm for bacterial strains and over 20 mm for fungal strains. The synergic effect was evidenced by comparing the antimicrobial results with chitosan/ZnO/CEO or chitosan/Ag/CEO simple films. According to the literature and our preliminary studies, these formulations are suitable as coating for fruits. The obtained nanocomposite films presented lower water vapor permeability values when compared with the chitosan control film. The samples were characterized by SEM, fluorescence and UV-Vis spectroscopy, FTIR spectroscopy and microscopy, and thermal analysis.

Properties of triticale protein films and their relation to plasticizing–antiplasticizing effects of glycerol and sorbitol

Triticale protein films were prepared and the influence of glycerol and sorbitol on their functional properties was investigated. At equal plasticizer concentration glycerol-plasticized triticale films had higher moisture content at a given relative humidity than did sorbitol films. Films plasticized with sorbitol exhibited higher solubility than glycerol-plasticized films. Mechanical properties of films are strongly affected by relative humidity and considerably varied with the type and concentration of plasticizer used. Glycerol exhibited better plasticizing effect for triticale films. Tensile strength, Young's modulus and puncture force of the films decreased as the glycerol content increased. The increase in the tensile strength and Young's modulus of the films containing low levels of sorbitol was ascribed to the antiplasticization of the films. Films prepared with sorbitol had lower water vapor permeability values but tended to be stiff and in some cases too brittle for tensile measurements. Sorbitol plasticization of the triticale protein films approached saturation at the plasticizer level of 50%. This work contributes to the understanding of the plasticizing–antiplasticizing effects of glycerol and sorbitol on properties of protein films and may be useful in the handling of these films as new food packaging systems, in accordance with the specific requirements of potential users.

Comparative study of processing methods for starch/gelatin films

In this work, the influence of processing methods on the properties of starch/gelatin films plasticized with glycerol and sorbitol is reported. Four different processing techniques: casting; pressing; pressing followed by blowing and extrusion followed by blowing were evaluated. Bioplastics prepared by casting were homogeneous and transparent with lower opacity and water vapor permeability (WVP) values when compared to films prepared by other techniques. Among the cast films studied, those with 3% lipophilic starch, in 1:1 proportions and plasticized with sorbitol, showed lower WVP values and higher tensile strength (TS). Films obtained by pressing and blowing showed little expansion during blow, had cracks in the surface, low TS and higher WVP. These films were the only samples to show crystallinity as determined by thermal analysis and X-ray diffraction. In conclusion, different processing techniques have significantly affected the properties of these films.

Effect of glycerol and coating weight on functional properties of biopolymer-coated paper

The effects of glycerol concentration and coating weight on biopolymer-coated paper properties were investigated using response surface methodology. Tests were run on the coated papers to determine water vapor barrier and mechanical properties. Coating weight was the most important parameter affecting water vapor permeability (WVP). Conversely, increasing coating weight led to a decrease in WVP and to an increase in tensile strength (TS) of the resulting coated papers. The papers coated with sodium caseinate (NaCAS) exhibited lower WVP values than those coated with other biopolymers. The TS of the papers coated with hydroxypropylmethylcellulose (HPMC) and chitosan was not affected by the glycerol concentration. HPMC-coated papers were higher in TS and %E than the other coated papers. For all types of coated paper, a maximum level of coating weight and level of glycerol concentration within range of 18.72–26.11% were found to be optimum for minimum WVP and maximum TS and %E.

Sodium dodecyl sulfate treatment improves properties of cast films from soy protein isolate

The manufacture of edible/biodegradable films or coatings can potentially add value to soy protein. This study was conducted to determine the effect of sodium dodecyl sulfate (SDS) on selected physical properties of glycerin-plasticized soy protein isolate (SPI) films. Films were cast from heated (70 °C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 ml water), glycerin (50% w/w of SPI), and SDS (0, 5, 10, 20, 30, or 40% w/w of SPI). Tensile strength (TS), elongation at break (E), moisture content (MC), total soluble matter (TSM), water vapor permeability (WVP), and color values ( L, a, and b) were determined after conditioning film specimens at 25 °C and 50% relative humidity (RH) for 2 days. SDS reduced ( P<0.05) film TS by as much as 43% for films with 40% SDS (6.2 vs. 10.9 MPa for control SPI films). In contrast, film E increased ( P<0.05) notably with addition of SDS even at 5%. Films with SDS had smaller ( P<0.05) MC and larger ( P<0.05) TSM values than control SPI films. Films containing 10% or more SDS had lower WVP values than control SPI films by as much as 50%. Increased yellowness, evidenced by greater ( P<0.05) + b color values, was noted for films with high amounts (20, 30, or 40%) of SDS. Changes in tensile, solubility, and water vapor barrier properties of SPI films due to the addition of SDS were largely attributed to disruption of hydrophobic associations among neighboring protein molecules as the non-polar portions of the SDS molecules attached onto hydrophobic amino acid residues within the film structure. It was demonstrated that adding anionic surfactant SDS to film-forming solutions prior to casting could greatly modify the properties of SPI films. In particular, SDS improved the water vapor barrier ability and the extendibility of SPI films, both desirable attributes when assessing the potential of such films for packaging applications.