New plasticizers for wheat gluten films

Influence of Curcuma Longa extract in citral addition on functional properties of thin films with triple-layer structure based on furcellaran and gelatin

In this study, we obtained triple-layer films based on furcellaran and gelatin, in which the middle layer was enriched with extract of Curcuma longa in citral. This newly developed material underwent a comprehensive characterisation process to identify significant improvements in its functional properties. Both SEM, XRD and FTIR analyzes indicated the formation of interactions not only between the components but also between the film layers. Notably, the incorporation of the natural extract led to a significant reduction in solubility, decreasing it from 74.79 % to 57.25 %, while enhancing thermal stability expressed as a melting point elevating it from 147.10 °C in the control film to 158.80 °C in the film with the highest concentration of the active ingredient. Simultaneously, the addition of this active ingredient resulted in decreased water contact angle (WCA) values, rendering the film more hydrophilic. The produced films exhibit great promise as packaging materials, particularly within the food industry, and the conducted research is marked by its forward-looking and developmental approach.

Selected Biopolymers' Processing and Their Applications: A Review

Petroleum-based polymers are used in a multitude of products in the commercial world, but their high degree of contamination and non-biodegradability make them unattractive. The development and use of polymers derived from nature offer a solution to achieve an environmentally friendly and green alternative and reduce waste derived from plastics. This review focuses on showing an overview of the most widespread production methods for the main biopolymers. The parameters affecting the development of the technique, the most suitable biopolymers, and the main applications are included. The most studied biopolymers are those derived from polysaccharides and proteins. These biopolymers are subjected to production methods that improve their properties and modify their chemical structure. Process factors such as temperature, humidity, solvents used, or processing time must be considered. Among the most studied production techniques are solvent casting, coating, electrospinning, 3D printing, compression molding, and graft copolymerization. After undergoing these production techniques, biopolymers are applied in many fields such as biomedicine, pharmaceuticals, food packaging, scaffold engineering, and others.

From mango by-product to food packaging: Pectin-phenolic antioxidant films from mango peels

The objective of the study was to prepare active films based on pectin and polyphenol-rich extracts from Tommy Atkins mango peels. Aqueous and methanolic extracts showed a variety of phenolic compounds that were identified by UPLC-MS analysis, and a high content of total phenolics that were quantified by the Folin-Ciocalteau method. The methanolic extract showed better results in antioxidant tests and was more effective in inhibiting the growth of Gram-positive and Gram-negative bacteria. The pectin extracted from mango peels showed good thermal stability and a degree of methoxylation of 58.3% by ¹H NMR. The films containing the phenolic extracts showed lower water vapor permeability when compared to the control film (without any phenolic extracts). The incorporation of the extracts led to an increase in elongation (ε) and a decrease in tensile strength (σ) and modulus of elasticity (Y). The films with aqueous or methanolic extracts showed higher antioxidant activity in terms of inhibition of the DPPH radical. Therefore, the films developed in this work are presented as a promising alternative for food packaging and/or coating applications.

Preparation and Characterization of Chinese Leek Extract Incorporated Cellulose Composite Films

This study aimed to prepare microcrystalline cellulose (MCC) films with good mechanical properties via plasticization using a Chinese leek (CL, Allium tuberosum) extract. The microstructure, crystal structure, mechanical properties, barrier ability, and thermal properties of the films were investigated. The chemical structure analysis of CL extract showed the existence of cellulose, lignin, and low-molecular-weight substances, such as polysaccharides, pectins, and waxes, which could act as plasticizers to enhance the properties of MCC:CL biocomposite films. The results of scanning electron microscopy and atomic force microscopy analyses indicated the good compatibility between MCC and CL extract. When the volume ratio of MCC:CL was 7:3, the MCC:CL biocomposite film exhibited the best comprehensive performance in terms of water vapor permeability (2.11 × 10^-10 g/m·s·Pa), elongation at break (13.2 ± 1.8%), and tensile strength (24.7 ± 2.5 MPa). The results of a UV absorption analysis demonstrated that the addition of CL extract improved the UV-shielding performance of the films. Therefore, this work not only proposes a facile method to prepare MCC films with excellent mechanical properties via plasticization using CL extract but also broadens the potential applications of MCC films in the packaging area.

Rice bran-based bioplastics: Effects of the mixing temperature on starch plastification and final properties

The agro-food industry produces huge amounts of wastes and by-products with high levels of carbohydrates and proteins, basic food groups that, properly treated, can be employed for the development of bioplastics. These high added-value products represent an alternative to traditional polymers. In this research work, rice bran was mixed with glycerol and water obtaining homogeneous blends which then are processed into bioplastics via injection moulding. The mixing temperature aids starch plastification and thus, affects the properties of the final specimens. In this way, the mechanical characterization revealed improvements for the highest temperature (110 °C) used which, at the same time, exhibited poor physical integrity during water immersion. Although the mechanical properties of the dried system obtained at 80 °C are slightly inferior to those obtained for the non-dried 110 °C system, these specimens are considered more adequate since they exhibited higher physical integrity and, consequently, better operating conditions.

Films from cashew byproducts: cashew gum and bacterial cellulose from cashew apple juice

ABSTRACT

Cashew is a major crop in several tropical countries. Its cultivation is mostly aimed to the production of cashew nuts, whereas its byproducts (including cashew tree gum and cashew apples) are underutilized. In this study, cashew tree gum (CG) has been combined to nanofibrillated bacterial cellulose (NFBC) produced from cashew apple juice, at different ratios (from CG-only to NFBC-only), to produce edible films. While the CG-only dispersion (at 1 wt%) behaved as a quasi-Newtonian fluid, the addition of NFBC provided a shear-thinning behavior, making the dispersions easier to process, especially to cast. Moreover, the films containing increasing NFBC contents exhibited better physico-mechanical performance. When compared to the CG-only film, the films containing at least 25% NFBC presented remarkably higher strength and modulus (even similar to some conventional petroleum-derived polymers), lower water vapor permeability (WVP), and lower water solubility, although at the expense of lower elongation and higher opacity values. The combined use of both polysaccharides was demonstrated to be useful to overcome the limitations of both CG-only films (very low viscosity, poor tensile properties and very high WVP) and NFBC-only films (very high viscosity, making the dispersions difficult to mix and spread). Moreover, the use of different NFBC/CG ratios allow properties to be tuned to meet specific demands for different food packaging or coating purposes.

GRAPHIC ABSTRACT

Antioxidant films and coatings based on starch and phenolics from Spondias purpurea L

The objective of this study was to prepare, for the first time, active films and coatings from fruit starch (SPFS) and phenolic stem bark extract (SBPE) from Spondias purpurea L. Starch film formulations were prepared with different SBPE contents (5-20 wt% on starch), then cast and dried into films. SBPE showed higher antioxidant activity and antimicrobial activity against both Gram-negative and Gram-positive bacteria. Chemical, morphological, thermal, optical, mechanical, and barrier properties were studied for SPFS-SBPE films. In general, the phenolic extract caused significant changes in starch films (especially when in excess), such as gradual reduction of elastic modulus and tensile strength, increased elongation, opacity, and thermal properties (e.g. glass transition and melting enthalpy). On the other hand, SBPE provided the films with active properties (antioxidant and UV-absorbing). Coatings were applied to minimally processed mangoes (MPM), which were stored for 10 days at 12 °C. SBPE-containing coatings provided better protective action, reducing the total color difference (∆E^⁎) and delaying the browning index (BI) during storage as well as reducing fungus attack. The active SPFS-SBPE films showed great potential as environmentally friendly active films and coatings.

Physicochemical properties of konjac glucomannan/alginate films enriched with sugarcane vinasse intended for mulching applications

Biodegradable films are a promising strategy to reduce the environmental impact caused by conventional plastics commonly used in agriculture. This study focused on the production and characterization of Konjac glucomannan (KGM) and alginate (ALG) based films enriched with sugarcane vinasse (VIN), a nutrient-rich wastewater generated in large volumes by the sugar-ethanol producing industries. ALG, KGM and ALG/KGM blended (50:50) films were produced by casting and treated with calcium ions (Ca²⁺) (ALG films) and a combination of Ca²⁺, alkali, and ethanol (KGM and ALG/KGM films). Vinasse addition tended to reduce transparency and water resistance of the films and had less effect on their mechanical properties. Crosslinking of ALG films resulted in enhanced mechanical properties and reduced moisture content, water solubility, swelling, water vapor permeability, and flexibility. KGM films were less impacted by crosslinking/deacetylation but showed improved water resistance while maintain a high degree of swelling (290% and 185% for KGM and KGM/VIN films respectively). Blended films exhibited characteristic properties of the two biopolymers and adequate compatibility indicated by Fourier transform infrared spectroscopy (FTIR) and morphologies. Vinasse-added ALG/KGM films represent a novel nutrient-enriched, bio-based material for agricultural applications and could help to face the environmental challenges imposed by vinasse disposal.

Evaluation of new environmental friendly particulate soil fertilizers based on agroindustry wastes biopolymers and sugarcane vinasse

This study evaluated the physicochemical and morphological properties of pectin and chitosan particles combined with sugarcane vinasse for soil fertilization applications. Particles were obtained by adding the biopolymeric solutions (pectin or chitosan solution) dropwise into the crosslinking solutions (calcium chloride 1% in ethanolic solution or tripolyphosphate 5% aqueous solution) followed by drying. Vinasse enhanced pectin gel stability improving pectin/vinasse particle properties. Physicochemical characterization indicated that vinasse nutrients were properly incorporated in both pectin and chitosan matrices. Particles showed spherical shape, with an average diameter of 3 and 2 mm for the pectin and chitosan particles with vinasse, respectively. Chitosan particles, compared to pectin, showed lower swelling capacity and solubility and higher mechanical resistance indicating a denser and more compact polymer network. Both particles were able to hinder water evaporation rates from sandy soil under water stress conditions. Biobased particles with vinasse added show potential to be applied as soil fertilizer representing an alternative to use and disposal of this expressive wastewater from sugar and alcohol industries.

Preparation and Characterization of Edible Dialdehyde Carboxymethyl Cellulose Crosslinked Feather Keratin Films for Food Packaging

The development of edible films based on the natural biopolymer feather keratin (FK) from poultry feathers is of great interest to food packaging. Edible dialdehyde carboxymethyl cellulose (DCMC) crosslinked FK films plasticized with glycerol were prepared by a casting method. The effect of DCMC crosslinking on the microstructure, light transmission, aggregate structure, tensile properties, water resistance and water vapor barrier were investigated. The results indicated the formation of both covalent and hydrogen bonding between FK and DCMC to form amorphous FK/DCMC films with good UV-barrier properties and transmittance. However, with increasing DCMC content, a decrease in tensile strength of the FK films indicated that plasticization, induced by hydrophilic properties of the DCMC, partly offset the crosslinking effect. Reduction in the moisture content, solubility and water vapor permeability indicated that DCMC crosslinking slightly reduced the moisture sensitivity of the FK films. Thus, DCMC crosslinking increased the potential viability of the FK films for food packaging applications, offering a value-added product.

Mechanical Reinforcement by Microalgal Biofiller in Novel Thermoplastic Biocompounds from Plasticized Gluten

The aim of this work was to develop new bioplastic compounds from wheat gluten, biobased plasticizers (glycerol, octanoic acid and 1,4-butanediol), and microalgal biomass as a filler. The effects of the composition on tensile properties, thermal stability, and water sensitivity were investigated. Microalgal biomass was added with the selected quantities: 10, 20, and 30 per hundred parts (php). Mechanical mixing of the components, i.e., gluten, plasticizer, and microalgae, was followed by molding in a hot press. Microlgal filler improved mechanical properties of the plasticized gluten material: in samples plasticized with 1,4-butanediol, 30 php of biomass increased the tensile modulus by nearly one order of magnitude, from 36.5 MPa to 273.1 MPa, and it also increased the tensile strength from 3.3 MPa to 4.9 MPa. The introduction of microalgal biomass slightly increased the surface sensitivity against water: 30 php of biomass reduced the water contact angle from 41° to 22° in samples plasticized with glycerol, but the biomass lowered the overall water absorption kinetics for material with each plasticizer. Microalgal biomass proved therefore to be an interesting sustainable resource with which to develop materials based on gluten, in particular to increase the mechanical properties of the compounds without reducing thermal stability or water resistance.

Process optimization of ultrasound-assisted treatment for soya bean protein isolate/polyacrylamide composite film

In this paper, composite films composed of soya bean protein isolate (SPI) and polyacrylamide (PAM) were prepared under variations of ultrasonic power, treatment time and heating temperature. The effects of the major processing parameters related to ultrasonic-assisted treatment were evaluated and optimized through the single-factor analysis and Box-Behnken design (BBD), respectively, when the tensile strength of composite films was considered as the response value. The single-factor analysis was carried out to study the effects of ultrasonic power, treatment time and heating temperature on the viscosity and cohesion of the slurry and the tensile strength of SPI/PAM composite films, which also provided a reasonable data range of each factor for further optimization. Experiment results indicated that these three factors play a significant role in the tensile strength of films. Then BBD was applied to optimize the treatment conditions of these three factors, using the tensile strength of films as the response value. According to the interactive second-order polynomial model of three factors and the three-dimensional response surface, the maximum tensile strength of films was obtained under the optimal condition. To verify the reliability of the model, the experiment with the optimal condition was conducted, and results demonstrated that the observed tensile strength was in agreement with the predicated one. Also, the morphology and water solubility of the films showed that the film can be coated on the yarns evenly and removed clearly.

Tuning the Functional Properties of Bitter Vetch (Vicia ervilia) Protein Films Grafted with Spermidine

Bitter vetch protein films containing positively charged spermidine, alone or with low amounts of glycerol, showed high tensile strength that progressively decreased by increasing the plasticizer concentration. Accordingly, lower film elongation at break and higher Young’s module values were detected in the presence of the polyamine without or with small amounts of glycerol. These data suggest that spermidine not only acts as a plasticizer itself by ionically interacting with proteins, but that it also facilitates glycerol-dependent reduction of the intermolecular forces along the protein chains, consequently improving the film flexibility and extensibility. Thus, spermidine may be considered not only as a primary, but also as a secondary plasticizer because of its ability to enhance glycerol plasticizing performance. Such double behavior of the polyamine was confirmed by the film permeability tests, since spermidine increased the barrier properties to gases and water vapor, while glycerol emphasized this effect at low concentrations but led to its marked reversal at high concentrations. Film microscopic images also substantiated these findings, showing more compact, cohesive, and homogeneous matrices in all spermidine-containing films.

Zein films with unoxidized or oxidized tannic acid

BACKGROUND

Corn zein is a predominatly hydrophobic protein, forming films with relatively good water resistance. Tannic acid, especially in its oxidized form, is supposed to cross-link proteins including zein, which may be explored to further enhance the water resistance of zein films. The effects of different contents (0-8 wt%) of unoxidized and oxidized tannic acid (uTA and oTA, respectively) on the properties of zein films at different pH values (4-9) were studied, according to central composite designs.

RESULTS

Increasing tannic acid contents and pH values resulted in decreased water solubility and increased tensile strength and modulus of films. The presence of tannic acid provided the films with a yellowish color and increased opacity. Paired t-tests indicated that oTA films presented higher tensile strength, lower water vapor permeability and lower water solubility than uTA films.

CONCLUSION

Higher tannic acid contents and pH values resulted in films with better overall physical properties, which might be ascribed to cross-linking, although the films were still not water resistant. The resulting films have potential to be used for food packaging and coating applications. © 2017 Society of Chemical Industry.

Wheat straw hemicelluloses added with cellulose nanocrystals and citric acid. Effect on film physical properties

Wheat straw has been used as a source of hemicelluloses (WSH) and cellulose nanocrystals (CNC) for the elaboration of biodegradable films. Different films have been formed by using WSH as a matrix and different contents of CNC and citric acid. The predominant hemicelluloses were arabinoxylans. CNC reinforced the films, improving tensile strength and modulus, water resistance and water vapor barrier. Citric acid, on the other hand, presented concomitant plasticizing and crosslinking effects (the latter also evidenced by FTIR), probably due to a crosslinking extension by glycerol. The use of 5.9wt% CNC and 30wt% citric acid was defined as optimal conditions, resulting in minimum water sensitivity and permeability, while maintaining a good combination of tensile properties. Under those conditions, the films presented enhanced modulus, elongation, water resistance, and barrier to water vapor when compared to the control WSH film, and might be used for wrapping or coating a variety of foods.

Effect of Plasticizer Type and Concentration on the Properties of Edible Film from Water-Soluble Fish Proteins in Surimi Wash-Water

Edible film made from water-soluble fish proteins present in surimi wash-water were developed based on formulation conditions explored in a previous study. Type and concentration of plasticizer significantly ( p < 0.05) affected the mechanical and barrier properties of the films. Sorbitol (SOR) plasticized films were the most brittle, with the highest tensile strength (TS, 3.14MPa) however its effect on water vapour permeability (WVP) was low (30.41g/mm/m2/d/kPa). In contrast, glycerol (GLY) and polyethylene glycol (PEG) plasticized films exhibited flexible structure despite a low TS (2.13MPa and 1.80MPa, respectively) resulting in higher WVP (125.8g/mm/m2/d/kPa and 89.52g/mm/m2/d/kPa). As plasticizer concentration increased, TS decreased concomitant with an increase in elongation as break (E) and higher WVP. SOR plasticized films, showed higher film solubility (FS) and protein solubility (PS) compared to GLY and PEG plasticized films. Increasing the plasticizer concentration, overall, resulted in both higher FS and PS. The colour of films was more affected by the nature of the plasticizer used than by its concentration.

Tuning the Functional Properties of Polysaccharide-Protein Bio-Based Edible Films by Chemical, Enzymatic, and Physical Cross-Linking

Among natural biopolymers, polysaccharides and proteins are very promising for biodegradable and edible wraps with different characteristics, so that their formulations can be tailor-made to suit the needs of a specific commodity. Films prepared from polysaccharides have good gas barrier properties but exhibit lower resistance to moisture compared to protein films (edible) or polylactide films (biodegradable). Protein-based films show better mechanical and oxygen barrier properties compared to polysaccharide films. For that reason, film performances may be enhanced by producing blend systems, where hydrocolloids (mixtures of proteins and/or polysaccharides) form a continuous and more cohesive network. However, the lower water barrier properties of hydrocolloid films and their lower mechanical strength in comparison with synthetic polymers limit their applications in food packaging. Therefore, the enhancement of biopolymer film properties has been studied to attain appropriate applications. This review provides an extensive synthesis of the improvement of the properties of edible polysaccharide-protein films by way of various chemical, enzymatic, and physical methods. These methods primarily aim at improving the mechanical resistance. They also permit to ameliorate the water and gas barrier properties and related functional properties.

Wheat Gluten Blends with Maleic Anhydride-Functionalized Polyacrylate Cross-Linkers for Improved Properties

A family of polyacrylate-based cross-linkers was synthesized to maximize the toughness of high Tg, high modulus wheat gluten blends in the glassy state. Mechanical testing and damping measurements were conducted to provide an example where the work of fracture and strength of the blend substantially exceeds polystyrene while maintaining flexure stiffness in excess of 3 GPa. The new rubbery cross-linkers, polymethyl acrylate-co-maleic anhydride and polyethyl acrylate-co-maleic anhydride, improve WG mechanical properties and reduce water absorption simultaneously. MDSC, FTIR, HPLC, and NMR data confirmed the cross-linking reaction with wheat gluten. Flexural, DMA, and water absorption testing were carried out to characterize the property improvements. DMA was conducted to investigate the relationship between energy damping and mechanical property improvement. If the cross-linker damping temperature is close to the testing temperature, the entire sample exhibits high damping, toughness, and strength.