Effect of Adding Red Propolis to Edible Biodegradable Protein Films for Coating Grapes: Shelf Life and Sensory Analysis.

Red propolis is an active ingredient of great nutritional interest which offers numerous benefits as an antioxidant and antimicrobial agent. Thus, the objective of this research was to evaluate the application of an edible and antimicrobial gelatine coating containing red propolis to increase the shelf life of grapes. Gelatine films with an addition of 5, 10, 15, 20 and 25% of red propolis extract were produced to evaluate their antimicrobial activity using the disk diffusion test in solid media. The films with 25% red propolis extract showed antimicrobial activity against the bacteria Staphylococcus aureus and Pseudomonas aeruginosa. The grapes were coated with pure gelatine, without a plasticizer and with gelatine with 25% red propolis and then stored for 1, 4, 10, 19 and 25 days at temperatures of 25 °C and 5 °C. The results showed that the gelatine coating with propolis reduced the mass loss of grapes stored at 25 °C for 19 days by 7.82% and by 21.20% for those kept at 5 °C for 25 days. The pH, total titratable acidity, soluble solids and color of the grapes increased due to the ripening process. Furthermore, the sensory acceptability indexes of the refrigerated grapes with coatings were superior (>78%) to those of the control samples (38%), proving the effectiveness of the coatings in maintaining the quality of grapes during storage.

Development and properties of biodegradable film from peach palm (Bactris gasipaes).

Formulations of biodegradable films using macrocarpa peach palm flour (low amylose starch), chitosan and glycerol, were developed and the effects of the drying temperature on films by assessing their physicochemical, mechanical, barrier, optical, structural, antioxidant properties, and the biodegradability in soil were evaluated. Chitosan enhanced the mechanical properties of the films, but they showed no antimicrobial activity against the tested food-borne pathogens, except for Listeria monocytogenes, for which the inhibition zone was from 0.1 to 0.6 cm. Films with higher concentrations of peach palm flour are opaquer, with better antioxidant characteristics and content of phenolic compounds compared to films made with lower concentrations of flour. The films presented a yellowish color because of the carotenoids found in peach palm flour, 29.63 µg 100 g-1, and exhibited a C-type X-ray pattern, characteristic peak of materials where amylose and amylopectin are present. After 15 days in soil, the films lost 30% of their initial weight. Therefore, these results suggest that the development of films as food preservative is a promising field and that the material used in the study are suitable for their formulation.

Improvements of thermal and mechanical properties of achira starch/chitosan/clay nanocomposite films.

Thermoplastic biofilms were developed from achira starch, chitosan and nanoclays using the solvent-casting method. To obtain the filmogenic solutions, different sonication times (0, 10, 20 and 30 min) were considered in order to evaluate the incidence of this parameter on the chemical and physico-mechanical properties of the bionanocomposite films. The chemical analysis using FTIR spectroscopy showed strong intermolecular interactions between the components with increasing sonication times. The results for tensile strength and elongation were satisfactory for films with 20 min of sonication with increases of 154% and 161%, respectively. Morphological analysis showed greater homogeneity, while thermal analysis showed that sonication favoured the plasticization process and thus, the production of homogeneous materials. The water absorption and wettability tests showed less hydrophilic materials allowing these new materials to be considered for use as coatings or packaging for the food sector.

Design of Biodegradable Films Using Pecan Nut Cake Extracts for Food Packing.

The excessive consumption of plastic packaging and its consequent disposal and accumulation in the environment have aroused the interest of researchers in developing packaging that can cause less harm to nature. In this sense, this article presents research on the addition of antioxidant extracts from pecan nut cake in biodegradable packaging made with a polymeric mixture of gelatin and corn starch. The films produced were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thickness, mechanical properties, water vapor permeability (WVP), solubility, water contact angle, optical properties, in vitro bioactive activity, and biodegradability. A higher concentration of total phenolic compounds (101.61 mg GAE/g) was found for the condition where alcohol content and extraction time were 65% and 20 min, respectively. Pecan nut cake (PNC( extracts did not influence the film's tensile strength, and elongation at break was tightly increased by adding 10-20% extracts. The film's characterization pointed to more than 67% solubility, and adding PNC extract implied more hydrophilic surfaces (contact angles lower than 65°). Furthermore, the film opacity showed a linear relation with PNC extract concentration, and a higher luminosity (L*) was observed for the film without extract. Furthermore, the antioxidant activity of the films was enhanced with the addition of PNC extracts, and complete biodegradation was observed until the ninth day. Therefore, biodegradable films prepared from a mixture of gelatin starch and enriched with PNC extracts showed excellent mechanical properties and potential as carriers of antioxidant compounds, allowing us to propose their use as active packing.

Biopolymers as green-based food packaging materials: A focus on modified and unmodified starch-based films.

The ideal food packaging materials are recyclable, biodegradable, and compostable. Starch from plant sources, such as tubers, legumes, cereals, and agro-industrial plant residues, is considered one of the most suitable biopolymers for producing biodegradable films due to its natural abundance and low cost. The chemical modification of starch makes it possible to produce films with better technological properties by changing the functional groups into starch. Using biopolymers extracted from agro-industrial waste can add value to a raw material that would otherwise be discarded. The recent COVID-19 pandemic has driven a rise in demand for single-use plastics, intensifying pressure on this already out-of-control issue. This review provides an overview of biopolymers, with a particular focus on starch, to develop sustainable materials for food packaging. This study summarizes the methods and provides a potential approach to starch modification for improving the mechanical and barrier properties of starch-based films. This review also updates some trends pointed out by the food packaging sector in the last years, considering the impacts of the COVID-19 pandemic. Perspectives to achieve more sustainable food packaging toward a more circular economy are drawn.

Characterization of Films Produced with Cross-Linked Cassava Starch and Emulsions of Watermelon Seed Oils.

Starches are promising molecules in the production of edible films. However, the hydrophilic nature of these materials is among the main limitations of packaging based on natural polymers. An underexplored alternative is the incorporation of emulsions. This work aimed to produce films based on crosslinked cassava starch with emulsions based on watermelon seed oil (WSO) extracted with pressurized ethanol. The effect of incorporating watermelon seed oil emulsion (WSOE) on the microscopic, structural, mechanical, hydrophilic, and thermal properties of films was analyzed. The internal structure and roughness of the films were significantly affected by increasing WSOE concentration. The WSOE incorporation increased the elongation capacity of the films and reduced the strain at break. WSOE concentrations did not significantly affect the water solubility, permeability, and X-ray diffraction but decreased the wettability of the films. The analysis of the thermal properties showed that the films did not present phase separation in the studied temperature range. Overall, WSOE improved the properties of the films based on cross-linked cassava starch, but it is necessary to optimize the production conditions of the films. These materials may potentially be used as biodegradable food packaging, controlled-release films, and edible coatings in food protection.

Preparation, Characterization and Evaluation of Antibacterial Properties of Polylactide-Polyethylene Glycol-Chitosan Active Composite Films.

Chitin is a natural biopolymer obtained from the exoskeleton of crustaceans. Chitosan is a derivative of chitin, which has antimicrobial properties and potential applications in several industries. Moreover, the composites of chitosan with other biodegradable polymers, such as polylactide (PLA) as packaging film, have shown promising results. In this study, chitosan was obtained and characterized from shrimp shells. Then, polylactide-chitosan composite films were prepared by a solvent casting technique using various amounts of chitosan (0.5-2% w/w) and polyethylene glycol as plasticizer (10% w/w). Thermal, mechanical properties, Fourier-transform infrared, scanning electron microscopy, as well as antibacterial properties of composite films were determined. It was found that adding chitosan (CH) into PLA films has a significant effect on tensile strength and no effect on thermal properties. The results showed a reduction on average of 1 log of colony-forming units against Staphylococcus aureus, while there is no antibacterial effect against Salmonella typhimurium. The study proved the antibacterial effect of CH in films of PLA against Gram-positive bacteria and appropriate mechanical properties. These films could be used for the development of biodegradable/eco-friendly food packaging prototypes, as a potential solution to replace conventional non-degradable packaging materials.

Effect of Chitosan Nanoparticles Incorporating Antioxidants from Salvia hispanica L. on the Amaranth Flour Films.

Research background: Amaranth (Amaranthus hypochondriacus) flour produces films with excellent barrier properties against water vapor, allowing food preservation, but the mechanical properties are poor compared to synthetic films. One strategy to improve these properties is the incorporation of nanoparticles. The particles can also serve as a vehicle for the addition of antioxidant agents into the films. The objective of this work is to optimize the formulation for the preparation of amaranth flour films treated with antioxidant chia (Salvia hispanica L.) extract-loaded chitosan particles using response surface methodology (RSM). Experimental approach: Chitosan nanoparticles with the extract were synthesized by ionic gelation, and the films were made by the casting method. Three independent variables were assigned: amaranth flour (4-6%), glycerol (25-35%) and chitosan nanoparticles loaded with the chia extract (0-0.75%). We then evaluated the physical (thickness), mechanical (tensile strength, Young´s modulus and elongation), barrier (water vapor permeability, moisture and water solubility) and antioxidant properties of the films. The experimental results of the properties were analyzed using a Box-Behnken experimental design generating 15 runs with three replicates at the central point. Results and conclusions: Second and third order polynomial models were obtained from the ANOVA analysis of the evaluated responses, and high coefficients of determination were found (0.91-1.0). The water vapor permeability of the films was 0.82-2.39·10-7 (g·mm)/(Pa·s·m2), tensile strength was 0.33-1.63 MPa and antioxidant activity 2.24-5.65%. The variables had different effects on the films: glycerol negatively affected their properties, and the permeability values increased with increased amaranth flour content. The nanoparticles improved the mechanical, barrier and antioxidant properties of the films compared to the films without nanosystems. The optimal formulation was 4% amaranth flour, 25% glycerol and 0.36% chitosan nanoparticles. The optimized films had better mechanical (1.62 MPa) properties, a low water vapor permeability value (0.91·10-7 (g·mm)/(Pa·s·m2)) and moderate antioxidant activity (6.43%). Novelty and scientific contribution: The results show the effect of chitosan nanoparticles on the properties of amaranth flour films for the first time. The resulting equations are useful in the design of food packaging.

Epoxidised sesame oil as a biobased coupling agent and plasticiser in polylactic acid/thermoplastic yam starch blends.

This work aims to improve the physicochemical properties of polylactic acid (PLA) and thermoplastic yam starch (TPS) blends using epoxidised sesame oil (ESO). We used epoxidised sesame oil from two Colombian Caribbean crops: Dioscorea rotundata and Sesamum indicum, with an oil substitution of 58.4 %. Films were obtained through extrusion and compression moulding processes. Moisture content, solubility, contact angle, and mechanical, barrier, and structural properties were determined using optical and scanning electron microscopy, infrared Fourier transform spectroscopy. Thermal analyses were also performed using thermogravimetry and differential scanning calorimetry techniques. The results suggest that the PLA and TPS interactions can be improved with the addition of ESO as coupling agent, enhancing the interfacial adhesion between the polymers, and favouring the smoothness of the film surface. Furthermore, the ESO addition led to increased thermal stability while restricting molecular mobility, indicating a coupling agent effect. In conclusion, the use of epoxidised oil for preparing films based on high PLA content and TPS allows obtaining enhanced interfacial adhesion. Considering the above, the developed materials have potential application in semi-rigid food packaging.

Microbial Colorants Production in Stirred-Tank Bioreactor and Their Incorporation in an Alternative Food Packaging Biomaterial.

Natural colorants from microbial fermentation have gained significant attention in the market to replace the synthetic ones. Talaromyces spp. produce yellow-orange-red colorants, appearing as a potential microorganism to be used for this purpose. In this work, the production of natural colorants by T. amestolkiae in a stirred-tank bioreactor is studied, followed by its application as additives in bio-based films. The effect of the pH-shift control strategy from 4.5 to 8.0 after 96 h of cultivation is evaluated at 500 rpm, resulting in an improvement of natural colorant production, with this increase being more significant for the orange and red ones, both close to 4-fold. Next, the fermented broth containing the colorants is applied to the preparation of cassava starch-based films in order to incorporate functional activity in biodegradable films for food packaging. The presence of fermented broth did not affect the water activity and total solids of biodegradable films as compared with the standard one. In the end, the films are used to pack butter samples (for 45 days) showing excellent results regarding antioxidant activity. It is demonstrated that the presence of natural colorants is obtained by a biotechnology process, which can provide protection against oxidative action, as well as be a functional food additive in food packing biomaterials.

Development and evaluation of edible films based on cassava starch, whey protein, and bees wax.

Films and edible coatings based on biopolymers have been developed as a packaging, which can be obtained from biodegradable materials and have properties similar to common plastics. These edible materials have many applications in the food industry, preventing mass transfer between the product and the surrounding environment. The objective of this study was to develop and evaluate the physicochemical and mechanical properties of edible films based on cassava starch (CS), whey protein (WP), and beeswax (BW). Response surface methodology has been used and the experiments were carried out based on face-centred composite design. On the other hand, three CS-based controls were formulated to evaluate the effect of the inclusion of WP and BW. The optimization of multiple responses established the optimal formulation: CS (3.17 %), WP (1.30 %), BW (0.50 %), presenting the following response variables: tensile stress (1.92 MPa), elongation (40.4 %), Young's modulus (42.1 MPa), water vapor permeability 1.79 × 10-11 (g mm/s cm2 Pa), swelling capacity (300.3 %), thickness (0.128 mm), moisture content (6.74 %), and colour: lightness (89.9), chromaticity a∗ (-1.8), chromaticity b∗ (7.7), saturation (9.9), tone (101.1°), and yellowness index (17.7). The selection and evaluation of this optimal formulation are essential because it is the material that shows the best possible mechanical and physicochemical properties using the studied components. The results, especially its good mechanical properties and low permeability to water vapour, would allow its application as a coating for fruits, vegetables, among others, effectively delaying its weight loss due to dehydration.

Characterization of insect chitosan films from Tenebrio molitor and Brachystola magna and its comparison with commercial chitosan of different molecular weights.

Insects are considered as alternative sources of chitosan; however, studies about the functional film-forming properties of insect chitosan are scarce. Insect chitosan films were made from Tenebrio molitor and Brachystola magna and were compared with commercial chitosan of different molecular weights (Mw). Mechanical properties (tensile strength, TS; elastic modulus, EM; elongation at break, %E), water vapor permeability (WVP) and physicochemical properties were characterized. The film properties of both commercial and insect chitosan were affected by Mw. Commercial chitosan films showed that at lower Mw, the TS (from 59 to 48 MPa) and EM (from 1471 to 1286 MPa) decreased; whereas WVP (from 2.9 × 10-11 to 3.4 × 10-11 g m-1s-1Pa-1), % E (from 38 to 41%) and solubility (from 30 to 33%) increased. Chitosan insect films showed lower TS and EM, and higher WPV, %E and solubility than commercial films. SEM revealed that chitosan insect films had lower porosity than commercial films. FTIR and X-ray diffraction showed not difference between insect and commercial chitosan films. These results showed that T. molitor and B. magna chitosan films could be used as a packaging material in several food products.

Nanocomposite Films of Chitosan-Grafted Carbon Nano-Onions for Biomedical Applications.

The design of scaffolding from biocompatible and resistant materials such as carbon nanomaterials and biopolymers has become very important, given the high rate of injured patients. Graphene and carbon nanotubes, for example, have been used to improve the physical, mechanical, and biological properties of different materials and devices. In this work, we report the grafting of carbon nano-onions with chitosan (CS-g-CNO) through an amide-type bond. These compounds were blended with chitosan and polyvinyl alcohol composites to produce films for subdermal implantation in Wistar rats. Films with physical mixture between chitosan, polyvinyl alcohol, and carbon nano-onions were also prepared for comparison purposes. Film characterization was performed with Fourier Transformation Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Tensile strength, X-ray Diffraction Spectroscopy (XRD), and Scanning Electron Microscopy (SEM). The degradation of films into simulated body fluid (SBF) showed losses between 14% and 16% of the initial weight after 25 days of treatment. Still, a faster degradation (weight loss and pH changes) was obtained with composites of CS-g-CNO due to a higher SBF interaction by hydrogen bonding. On the other hand, in vivo evaluation of nanocomposites during 30 days in Wistar rats, subdermal tissue demonstrated normal resorption of the materials with lower inflammation processes as compared with the physical blends of ox-CNO formulations. SBF hydrolytic results agreed with the in vivo degradation for all samples, demonstrating that with a higher ox-CNO content increased the stability of the material and decreased its degradation capacity; however, we observed greater reabsorption with the formulations including CS-g-CNO. With this research, we demonstrated the future impact of CS/PVA/CS-g-CNO nanocomposite films for biomedical applications.

Production of bioactive films of carboxymethyl cellulose enriched with green coffee oil and its residues.

Carboxymethyl cellulose (CMC)-based films were developed by incorporating green coffee oil (GCO) obtained by cold pressing and hydroalcoholic extracts of its residues. The effect of cake (CE) and sediment extracts (SE) in different proportions (20-40%) and GCO on chemical, morphological, physical, mechanical, optical, and antioxidant properties of the films was investigated. Eight fatty acids and four major phenolic compounds were identified by High-Resolution Direct-Infusion Mass Spectrometry in GCO and residue extracts. FTIR indicated interactions among CMC, phenolic compounds, and fatty acids. Films enriched with residue extracts presented heterogeneous microstructure. The tensile strength of the films decreased from 58 to 3 MPa with the extracts concentration, while elongation increased from 28 to 156% (p < 0.05). The water vapor permeability (averaging 3.94 × 10-8 g mm/cm2 h Pa) was not significantly affected by the extracts and GCO. The surface color was influenced by the type and concentration of extracts (p < 0.05), the film with SE40% had remarkable UV-vis barrier properties. The incorporation of GCO residue extracts imparted high antioxidant capacity to the CMC-based films, especially with CE40% (643.8 µmol Trolox eq./g dried film; 51.3 mg GAE/g dried film). General observations indicated the potential of these films, mainly the ones containing CE, like active packaging material for food applications.

Effect of Chitosan Addition in Whey-based Biodegradable Films

Abstract Whey, a by-product of dairy industry, is a feedstock widely employed in the production of biodegradable films. However, these films present some limitations when considering the performance of synthetic polymers, especially biological transformation by decomposition. This work aimed to evaluate the effects of chitosan addition to whey-based films to improve films physical-chemical properties and resistance to microbial degradation. The results showed that there was an interaction effect between the chitosan concentration and the storage time for the physical-chemical properties of elongation at break and opacity. There was statistical difference among the formulations; however, for the moisture content and film thickness, there was no interaction effect between the formulation and the storage time. The films with 1.5 and 3.0 wt.% chitosan presented a yellowish hue, characteristic of the polysaccharide; this could also be detected by SEM analysis. The films presented an excellent biodegradability, being decomposed in about 8 days. Considering all chitosan contents tested had similar performances, the chitosan content of 0.15 wt.% was the one with the better cost-benefit relation.

Preparation of Chitosan/Poly(Vinyl Alcohol) Nanocomposite Films Incorporated with Oxidized Carbon Nano-Onions (Multi-Layer Fullerenes) for Tissue-Engineering Applications.

Recently, tissue engineering became a very important medical alternative in patients who need to regenerate damaged or lost tissues through the use of scaffolds that support cell adhesion and proliferation. Carbon nanomaterials (carbon nanotubes, fullerenes, multi-wall fullerenes, and graphene) became a very important alternative to reinforce the mechanical, thermal, and antimicrobial properties of several biopolymers. In this work, five different formulations of chitosan/poly(vinyl alcohol)/oxidized carbon nano-onions (CS/PVA/ox-CNO) were used to prepare biodegradable scaffolds with potential biomedical applications. Film characterization consisted of Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tension strength, Young's modulus, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The degradation in a simulated body fluid (FBS) demonstrated that all the formulations lost between 75% and 80% of their weight after 15 days of treatment, but the degradation decreased with the ox-CNO content. In vivo tests after 90 days of subdermal implantation of the nanocomposite films in Wistar rats' tissue demonstrated good biocompatibility without allergenic reactions or pus formation. There was a good correlation between FBS hydrolytic degradation and degradation in vivo for all the samples, since the ox-CNO content increased the stability of the material. All these results indicate the potential of the CS/PVA/ox-CNO nanocomposite films in tissue engineering, especially for long-term applications.

Antimicrobial Films Based on Nanocomposites of Chitosan/Poly(vinyl alcohol)/Graphene Oxide for Biomedical Applications.

Today, tissue regeneration is one of the greatest challenges in the field of medicine, since it represents hope after accidents or illnesses. Tissue engineering is the science based on improving or restoring tissues and organs. In this work, five formulations of chitosan/poly(vinyl alcohol)/graphene oxide (CS/PVA/GO) nanocomposites were studied for the development of biodegradable films with potential biomedical applications. The characterization of the films consisted of Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The antibacterial activity was evaluated in vitro against Gram-positive bacteria Bacillus cereus and Staphylococcus aureus and Gram-negative Salmonella spp. and Escherichia coli, by contact of the film above inoculum bacterial in Müeller⁻Hinton agar. On the other hand, in vivo tests in which the material implanted in the subcutaneous tissue of Wistar rats demonstrated that the formulation CS/PVA/GO (14.25:85:0.75) was the best antibacterial film with adequate degradation in vivo. All together, these results indicate the potential of the films using nanocomposites of CS/PVA/GO in tissue engineering and cell regeneration.

Physical properties of films based on pectin and babassu coconut mesocarp.

The objective of this research was to study the physical properties, water sorption, thermal and structure of films made from citrus pectin (CP), babassu coconut mesocarp (BCM) and glycerol (G). Seventeen formulations were prepared according to a central compound rotational design combining different proportions of the materials and evaluating the films produced according to their moisture contents, solubility, thicknesses and water vapor permeability. The results showed a direct relationship between the composition of the film and each physical property, providing films with unique mechanical characteristics and barrier properties. In the second phase, the films were reformulated, maintaining the proportions of CP and BCM constant and altering the G content. The results showed films with permeable structures, thus favoring the use of high drying temperatures (up to 70 °C) for the confection of films, without altering their physical and structural properties.

Characteristics of starch from different bean genotypes and its effect on biodegradable films.

BACKGROUND: Starches from four common bean genotypes were characterized and used in the production of biodegradable films. Starches were characterized by their swelling power, solubility, amylose content, granule morphology, relative crystallinity, thermal and pasting properties, and susceptibility to α-amylase hydrolysis. Films were characterized according to their morphology, mechanical and water vapor barrier properties, whiteness and opacity. RESULT: Depending on the common bean genotype, a great variation on starch properties was found, which, in turn, clearly impacted on the characteristics of the starch-based films. Starches from BRS Pitanga and BRS Pérola genotypes exhibited the highest amylose content and the lowest swelling capabilities. Bean starch from the IPR Uirapuru genotype presented granules with an irregular surface and shape. Starches from IPR Uirapuru and BRS Estilo genotypes provided well-structured biodegradable films, without the occurrence of fissures or cracks. Moreover, starch films containing starch from BRS Estilo genotype exhibited the highest flexibility, permeability and solubility. CONCLUSION: The morphological, mechanical and water vapor barrier properties of films elaborated with common bean starch vary greatly as a function of the bean genotype used for starch production. © 2018 Society of Chemical Industry.

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.