Edible carboxymethyl cellulose films containing natural antioxidant and surfactants: α-tocopherol stability, in vitro release and film properties

Development and characterization of cranberry pomace extract incorporated and vitamin E fortified edible films as an edible separation sheet for fruit leather

The separation sheets for fruit leather are traditionally made of plastic film or wax paper, which not only leads to environmental issues but also is inconvenience to consumers. This study evaluated edible fruit leather separation sheets using food polymers, including hydroxypropyl methyl cellulose (HPMC) and incorporation of cranberry pomace water extract (CPE) for providing natural fruit pigment, flavor, and phenolics. HPMCCPE film was then further improved by incorporating hydrophobic compound (oleic acid, OA) and vitamin E (VE) via cellulose nanocrystal (CNC) Pickering emulsion (CNCP) for enhancing film hydrophobicity and nutritional benefit, respectively. The CNCP-HPMCCPE film exhibited reduced water vapor permeability (∼0.033 g mm/m2 d Pa) compared to HPMCCPE film (∼0.59 g mm/m2 d Pa) and had the least change in mass and moisture content when wrapping fruit leather for up to 2 weeks of ambient storage. The fruit leather wrapped by CNCP-HPMCCPE film showed lower weight change than those by films without CNCP due to low mass transfer between film and fruit leather. CNCP resulted in controlled release of VE into a food simulating solvent (ethanol). The developed colorful and edible fruit leather separation sheet satisfied the increased market demands on sustainable food packaging. PRACTICAL APPLICATION: Colorful and flavorful edible films made of edible polymers, fruit pomace water extract, and emulsified hydrophobic compounds with vitamin E were created. The films have the satisfactory performance to replace the conventional fruit leather separation sheet made of plastic or wax paper. The edible films can be eaten with packaged fruit leather for not only reducing packaging waste but also providing convenience and nutritional benefit to consumers. These functional edible films may also be utilized to package other food products for promoting packaging sustainability and nutritional benefit.

Polysaccharides and proteins based bionanocomposites as smart packaging materials: From fabrication to food packaging applications a review

Food industry is the biggest and rapidly growing industries all over the world. This sector consumes around 40 % of the total plastic produced worldwide as packaging material. The conventional packaging material is mainly petrochemical based. However, these petrochemical based materials impose serious concerns towards environment after its disposal as they are nondegradable. Thus, in search of an appropriate replacement for conventional plastics, biopolymers such as polysaccharides (starch, cellulose, chitosan, natural gums, etc.), proteins (gelatin, collagen, soy protein, etc.), and fatty acids find as an option but again limited by its inherent properties. Attention on the initiatives towards the development of more sustainable, useful, and biodegradable packaging materials, leading the way towards a new and revolutionary green era in the food sector. Eco-friendly packaging materials are now growing dramatically, at a pace of about 10-20 % annually. The recombination of biopolymers and nanomaterials through intercalation composite technology at the nanoscale demonstrated some mesmerizing characteristics pertaining to both biopolymer and nanomaterials such as rigidity, thermal stability, sensing and bioactive property inherent to nanomaterials as well as biopolymers properties such as flexibility, processability and biodegradability. The dramatic increase of scientific research in the last one decade in the area of bionanocomposites in food packaging had reflected its potential as a much-required and important alternative to conventional petroleum-based material. This review presents a comprehensive overview on the importance and recent advances in the field of bionanocomposite and its application in food packaging. Different methods for the fabrication of bionanocomposite are also discussed briefly. Finally, a clear perspective and future prospects of bionanocomposites in food packaging were presented.

Incorporation of α-Tocopherol into Pea Protein Edible Film Using pH-Shifting and Nanoemulsion Treatments: Enhancing Its Antioxidant Activity without Negative Impacts on Mechanical Properties

The aim of this study is to develop an antioxidant film based on pea protein isolate (PPI) without sacrificing the packaging properties. To achieve this, α-tocopherol was incorporated to impart antioxidant activity to the film. We investigated the effects on film properties resulting from the addition of α-tocopherol in a nanoemulsion form and pH-shifting treatment of PPI. The results revealed that direct addition of α-tocopherol into un-treated PPI film disrupted film structure and formed a discontinuous film with rough surface, and thereby significantly decreasing the tensile strength and elongation at break. However, pH-shifting treatment in combination with the α-tocopherol nanoemulsion, formed a smooth and compact film, which greatly improved the mechanical properties. It also significantly changed the color and opacity of PPI film, but had little effects on film solubility, moisture content, and water vapor permeability. After the addition of α-tocopherol, the DPPH scavenging ability of PPI film was greatly improved and the release of α-tocopherol was mainly within the first 6 h. Additionally, pH-shifting and nanoemulsion did not affect the film's antioxidant activity nor the release rate. In conclusion, pH-shifting combined with nanoemulsion is an effective method to incorporate hydrophobic compounds such as α-tocopherol into protein-based edible films without negative impacts on film mechanical properties.

Novel Features of Cellulose-Based Films as Sustainable Alternatives for Food Packaging

Packaging plays an important role in food quality and safety, especially regarding waste and spoilage reduction. The main drawback is that the packaging industry is among the ones that is highly dependent on plastic usage. New alternatives to conventional plastic packaging such as biopolymers-based type are mandatory. Examples are cellulose films and its derivatives. These are among the most used options in the food packaging due to their unique characteristics, such as biocompatibility, environmental sustainability, low price, mechanical properties, and biodegradability. Emerging concepts such as active and intelligent packaging provides new solutions for an extending shelf-life, and it fights some limitations of cellulose films and improves the properties of the packaging. This article reviews the available cellulose polymers and derivatives that are used as sustainable alternatives for food packaging regarding their properties, characteristics, and functionalization towards active properties enhancement. In this way, several types of films that are prepared with cellulose and their derivatives, incorporating antimicrobial and antioxidant compounds, are herein described, and discussed.

Preparation and characterization of edible carboxymethyl cellulose films containing natural antibacterial agents: Lysozyme

Carboxymethyl cellulose (CMC) films containing lysozyme (Lys) were prepared in this study and changes in properties of the films were investigated. Enhancement in mechanical properties was observed with increased Lys, maximum (0.05 g/100 mL) reached to 39.07 MPa (TS) and 25.04 % (EAB). Meanwhile, water resistance ability improved, the minimum (0.05 g/100 mL) reached to 0.42 g·mm·(m²·h·KPa)^-1, 84.62 % of pure CMC film. Thermogravimetric test showed better thermal stability of films. Scanning electron microscope illustrated that few cracks on surface of films. Fourier Transform infrared spectroscopy supported that more intermolecular hydrogen between Lys and CMC was formed with increased Lys, yet keeping increasing formed less intermolecular hydrogen. X-ray Diffraction observed the aggregated Lys by crystal structure. Antibacterial test showed an inhibitory effect on two common food-borne pathogens. Weight loss experiment indicated that films reduced the dry consumption of meat. Overall, the modification of CMC film by adding Lys was effective.

Drying Regimes on Regenerated Cellulose Films Characteristics and Properties

Abundant water content and its interaction with cellulose macromolecules through hydrogen bonding engenders a complex drying process, the circumstances of which have not yet been unveiled. For instance, excessive drying on regenerated cellulose membranes (RCM) causes cracking and severe shrinking, affecting the produced regenerated cellulose film (RCF). Thus, mathematical models in estimating the drying kinetics and required energy to dry RCM are necessary. This study evaluated two drying techniques of oven drying and infrared (IR) drying on RCM at different temperatures of 50–80 °C. Five mathematical models were used, namely Newton, Page, Handreson–Pabis, logarithmic, and Wang–Singh, to adjust the obtained experimental data and were statistically validated using ANOVA to review their effect on the quality of the produced RCF. A logarithmic model and a Wang–Singh model were the best models for oven drying and IR drying of RCM, respectively. It was found that the physical property of the RCF was similar to all drying types. Meanwhile, for mechanical properties, the high temperature of oven drying affected the tensile properties of RCF compared with IR drying. This study is beneficial by approximating the drying kinetics of RCM and defining appropriate drying conditions, which controls the quality of its predictive physical and mechanical properties.

Edible coatings and lipid oxidation data in walnuts

The information presented is part of an investigation that seeks a better understanding of lipid oxidation in walnuts. The data shown regarding edible coating, are one of the strategies used to investigate the effect over oxidation stability. For the present experiments, unshelled walnuts were coated with different formulations, and then stored at 37 °C, 20% RH for 6 weeks. After that time, coated nuts were taken out, cold pressed to extract the oil and analysed. The main data obtained from the oil analysis of walnuts were acid value, peroxide value, and thiobarbituric acid reactive substances (TBARS). Data show the variation of the parameters during the storage time at 37 °C, considering the different formulations of edible coatings and the control. These data are relevant to walnuts exporters to have a comparison point.

Comprehensive Review of Polysaccharide-Based Materials in Edible Packaging: A Sustainable Approach

Edible packaging is a sustainable product and technology that uses one kind of "food" (an edible material) to package another kind of food (a packaged product), and organically integrates food with packaging through ingenious material design. Polysaccharides are a reliable source of edible packaging materials with excellent renewable, biodegradable, and biocompatible properties, as well as antioxidant and antimicrobial activities. Using polysaccharide-based materials effectively reduces the dependence on petroleum resources, decreases the carbon footprint of the "product-packaging" system, and provides a "zero-emission" scheme. To date, they have been commercialized and developed rapidly in the food (e.g., fruits and vegetables, meat, nuts, confectioneries, and delicatessens, etc.) packaging industry. However, compared with petroleum-based polymers and plastics, polysaccharides still have limitations in film-forming, mechanical, barrier, and protective properties. Therefore, they need to be improved by reasonable material modifications (chemical or physical modification). This article comprehensively reviews recent research advances, hot issues, and trends of polysaccharide-based materials in edible packaging. Emphasis is given to fundamental compositions and properties, functional modifications, food-packaging applications, and safety risk assessment of polysaccharides (including cellulose, hemicellulose, starch, chitosan, and polysaccharide gums). Therefore, to provide a reference for the development of modern edible packaging.

Advantages and challenges of Pickering emulsions applied to bio-based films: a mini-review

The strategy of adding hydrophobic compounds to bio-based films (usually based on hydrophilic matrices), forming films containing emulsions, is a technique that has been used to improve some physical properties (such as reducing water solubility and water vapor permeability) and / or to impart properties, such as antioxidant and antimicrobial effects by carrying hydrophobic active components that would otherwise be insoluble in hydrophilic matrices. Although Pickering emulsions have been reported as presenting greater stability when compared with surfactant-stabilized emulsions, little is known about the drying stability of Pickering emulsions (which is important for film applications). Anyway, several studies have indicated that Pickering emulsions are interesting systems to improve the water vapor barrier properties of bio-based films and coatings, and to act as carriers of active hydrophobic components. On the other hand, the tensile properties of those films are usually impaired by the presence of Pickering emulsions. The objective of this review is to present recent developments and future perspectives in bio-based films loaded with Pickering emulsions. © 2020 Society of Chemical Industry.

Recent Developments of Carboxymethyl Cellulose

Carboxymethyl cellulose (CMC) is one of the most promising cellulose derivatives. Due to its characteristic surface properties, mechanical strength, tunable hydrophilicity, viscous properties, availability and abundance of raw materials, low-cost synthesis process, and likewise many contrasting aspects, it is now widely used in various advanced application fields, for example, food, paper, textile, and pharmaceutical industries, biomedical engineering, wastewater treatment, energy production, and storage energy production, and storage and so on. Many research articles have been reported on CMC, depending on their sources and application fields. Thus, a comprehensive and well-organized review is in great demand that can provide an up-to-date and in-depth review on CMC. Herein, this review aims to provide compact information of the synthesis to the advanced applications of this material in various fields. Finally, this article covers the insights of future CMC research that could guide researchers working in this prominent field.

Active coatings of thermoplastic starch and chitosan with alpha-tocopherol/bentonite for special green coffee beans

The quality of green coffee beans (GCBs) is possibly affected by storage conditions. Edible polymer coatings for GCBs can help preserve flavors and improve shelf life of GCBs. This study aimed to incorporate α-tocopherol, a powerful antioxidant, in thermoplastic starch [TPS] and chitosan [TPC] and determined the best cavitation energy (960-3840 J·mL-1) using an ultrasonic probe. Then, we evaluated the incorporation of bentonite (0% and 2% m/m) and α-tocopherol (0% and 10% m/m) in the best energy cavitation/biopolymer combination. The TPS and TPC coatings demonstrated good adherence to the GCBs, measured by surface energy. The dispersion of α-tocopherol in TPC, with cavitation energy 960 J·mL-1, promoted greater stability (greater zeta potential), thereby increasing antioxidant activity by 28% compared to TPS, therefore, was selected for a second stage. Incorporation of 2% bentonite into the TPC, with 10% α-tocopherol, resulted in a 3.7 × 10-10 g·m-1·s-1·Pa-1 water vapor permeability, which is satisfactory for prevented of moisture gain during storage. The compressive load showed values of 375 N to the non-coated GCB and around 475 N with the insertion of coatings to the GCB. Thus, a TPC/α-tocopherol/bentonite combination, dispersed with 960 J·mL-1 energy, was highly effective in the development of biopolymeric coatings for the GCBs.

Real-Time Visualization of Cellulase Activity by Microorganisms on Surface

A variety of methods to detect cellulase secretion by microorganisms has been developed over the years, none of which enables the real-time visualization of cellulase activity on a surface. This visualization is critical to study the interaction between soil-borne cellulase-secreting microorganisms and the surface of plant roots and specifically, the effect of surface features on this interaction. Here, we modified the known carboxymethyl cellulase (CMC) hydrolysis visualization method to enable the real-time tracking of cellulase activity of microorganisms on a surface. A surface was formed using pure CMC with acridine orange dye incorporated in it. The dye disassociated from the film when hydrolysis occurred, forming a halo surrounding the point of hydrolysis. This enabled real-time visualization, since the common need for post hydrolysis dyeing was negated. Using root-knot nematode (RKN) as a model organism that penetrates plant roots, we showed that it was possible to follow microorganism cellulase secretion on the surface. Furthermore, the addition of natural additives was also shown to be an option and resulted in an increased RKN response. This method will be implemented in the future, investigating different microorganisms on a root surface microstructure replica, which can open a new avenue of research in the field of plant root-microorganism interactions.

Functional Properties of Biopolymer-Based Films Modified with Surfactants: A Brief Review

An increase of environmental awareness recently has increased the interest of researchers in using of biopolymer-based films. The films have been prepared extensively by utilizing starch, carboxymethyl cellulose, chitosan, protein, gelatin, carrageenan, alginate, pectin, guar gum and pullulan. They are typically modified with surface-active agents (surfactants) such as glycerol monostearate, sucrose ester, sodium stearoyl lactate, sodium dodecyl sulfate, ethyl lauroyl arginate HCl, Span 20 to 80, Tween-20 to 80 and soy lecithin for improving the functional properties of the films. In this brief review, two types of biopolymer-based films that prepared through casting method were categorized, specifically solution- and emulsion-based films. The four types of surfactants, namely non-ionic, anionic, cationic and amphoteric surfactants that are regularly used to modify biopolymer-based films are also described. The functional properties of the films modified with different types of surfactants are briefly reviewed. This study enhances the attraction of researchers in biopolymer-based films and the improvement of new concepts in this niche area.

Introducing nano/microencapsulated bioactive ingredients for extending the shelf-life of food products

The shelf-life of foods is affected by several aspects, mainly chemical and microbial events, resulting in a considerable decline in consumer's acceptance. There is an increasing interest to substitute synthetic preservatives with the plant-based bioactive ingredients which are safe and natural. However, full implementation of this replacement is postponed by some challenges associated with bioactive ingredients, including their low chemical stability, off-flavor, low solubility, and short-term effectiveness. Encapsulation could overcome these limitations. The present review explains current trends in applying natural encapsulated ingredients for food preservation based on a classified description including essential oils, plant extracts, phenolics, carotenoids, etc. and their application for extending food shelf-life mostly dealing with antimicrobial, ant-browning and antioxidant properties. Encapsulation techniques, especially nanoencapsulation, is a promising strategy to overcome their limitations. Moreover, better results are obtained using a combination of proteins and polysaccharides as wall materials than single polymers. The encapsulation method and type of encapsulants highly influences the releasing mechanism and physicochemical properties of bioactive ingredients. These factors together with optimizing the conditions of encapsulation process leads to a cost-effective and well encapsulated ingredient which is more efficient than its free form in shelf-life improvement. It has been shown that the well-designed encapsulation systems, finally, boost the shelf-life-promoting functions of the bioactive ingredients, mostly due to enhancing their solubility, homogeneity in food matrices and contact surface with deteriorative agents, and providing their prolonged presence over food storage and processing via increasing the thermal and processing stability of bioactive compounds, as well as controlling their release on food surfaces, or/and within food packages. To this end and given the numerous wall and bioactive core substances available, further studies are needed to evaluate the efficiency of many encapsulated forms of both conventional and novel bioactive ingredients in food shelf-life extending since the interactions and anti-spoiling behaviors of the ingredients in various encapsulation systems and foodstuffs are highly variable that should be optimized and characterized before any industrial application.

Characterization of whey protein-based films incorporated with natamycin and nanoemulsion of α-tocopherol

Food packaging materials are commonly derived from petroleum that increases global contamination; this raises the interest to evaluate raw material from renewable sources such as whey protein for the development of packaging materials, especially to produce active films. This research aimed to evaluate whey protein-based film properties when natamycin, nanoemulsioned α-tocopherol, or both were added. An oil-in-water (O/W) nanoemulsion of antioxidant (α-tocopherol) was prepared by microfluidization technique. Four films were prepared with different levels of natamycin and nanoemulsified α-tocopherol and were characterized in terms of physicochemical, mechanical, optical-properties, water vapor barrier, FTIR, microstructure, antioxidant and antimicrobial activity. The natamycin, nanoemulsified α-tocopherol, or both did not modify the moisture content of the films. Moreover lead to a significant reduction of tensile strength and elastic modulus, while presenting growth in the elongation at break. Film opacity, the total color difference, the UV-Vis light barrier, and the water vapor permeability values increased when compounds were incorporated into the film. The microstructure studies showed uniformly distributed porosity throughout the films. The addition of nanoemulsioned α-tocopherol into whey protein-based films provoked antioxidant activity and the addition of natamycin produced films with effectivity against C. albicans, P. chrysogenum, and S. cerevisiae, allowing develop a material appropriate for use as active food packaging.

Properties of novel chitosan incorporated with hexahydro-β-acids edible films and its effect on shelf life of pork

Edible packaging films have been widely studied because of its safety, green, and effective characteristics. In this paper, chitosan (CH) edible films containing hexahydro-β-acids (HBA) were prepared, and its physical and mechanical properties, bioactivity, and their impact on the shelf life of pork were investigated. The infrared spectra indicated that the molecular interaction between CH and HBA was observed. Scanning electron microscopy was used to analyze the surface morphology of the film, and light transmittance analysis displayed that the addition of HBA enhanced the film's UV blocking performance. Compared to the CH film, the tensile strength of CH-HBA film increased to 29.19 ± 0.45 MPa, and the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) reached 1.40 ± 0.01 mg rutin/cm² of the film. The antibacterial activity of the CH-HBA film on Escherichia coli (44825) and Staphylococcus aureus (26001) showed that the CH-HBA film is a feasible antibacterial package. Furthermore, compared to pork packaged in CH and polyethylene films, fresh pork packaged with CH-HBA films displayed prolongation of shelf life due to reduction in microbial proliferation, thiobarbituric values, pH, and total volatile base nitrogen contents during storage at 4 °C for 16 days. The freshness of pork was prolonged by 7-8 days when the dosage of HBA was increased to 0.3% from 0.1% (w/v). These results revealed that the CH-HBA film can effectively extend the shelf life of pork. PRACTICAL APPLICATION: This study effectively prolonged the shelf life of pork. A chitosan-edible film combined with hexahydro-β-acids has a potential application value in replacing traditional packaged fresh meat.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.

Preparation of multifunctional carboxymethyl cellulose-based films incorporated with chitin nanocrystal and grapefruit seed extract

Chitin nanocrystals (ChNC) were isolated from shrimp shells powder using acid hydrolysis and ammonium persulfate methods. Multifunctional carboxymethyl cellulose (CMC) composite films were prepared by adding ChNC and grapefruit seed extract (GSE), and their effects on the optical, mechanical, water vapor barrier, and antibacterial properties of CMC film were investigated. The isolated ChNC had a needle-like structure with a length of 340-370 nm and a diameter of 18-20 nm depending on the isolation method. The CMC films prepared with ChNC and GSE were transparent with high UV barrier properties. The addition of GSE reduced the strength (TS) and stiffness (EM) of CMC films by 10.4% and 30.3%, respectively, while the flexibility (EB) increased by 17.7%. However, when the ChNC was added, the TS and EM of CMC film increased by 19.7% and 58.7%, respectively, and the EB remained the same. The addition of ChNC reduced the water vapor permeability (WVP) of the CMC film by 27%. CMC films containing GSE also showed strong antibacterial activity against foodborne pathogenic bacteria, E. coli and L. monocytogenes.

Poly (α-Dodecyl γ-Glutamate) (PAAG-12) and Polylactic Acid Films Charged with α-Tocopherol and Their Antioxidant Capacity in Food Models

Poly (α-dodecyl γ-glutamate) (PAAG-12) was successfully synthesized from poly(γ-glutamic acid) (PGGA) according to Nuclear Magnetic Resonance (NMR) analyses. PAAG-12 films were prepared and enriched with 5% α-tocopherol, with the aim of using them as novel antioxidant active packaging for food applications. Thermogravimetric Analysis (TGA) characterization determined that α-tocopherol improved thermal stability of films, which is beneficial for industrial processing. Polylactic Acid (PLA) films prepared with the same amount of α-tocopherol were used to set a comparative frame and both types of films were applied to two different food models to assess their protective action against oxidation. Water, 50% ethanol (EtOH) and 95% EtOH were used as food simulants and HPLC analyses were performed to determine diffusion and partition coefficients in PLA and the novel polymer, the latter exhibiting slower release rates. Primary oxidation was measured with peroxide value, which revealed that PAAG-12 films with α-tocopherol protected oil-in-water (O/W) emulsions up to 29 days, complying with the Codex Alimentarius.

A Natural Peanut Edible Coating Enhances the Chemical and Sensory Stability of Roasted Peanuts

This study aims to assess the enhancement of the chemical and sensory properties of roasted peanuts during storage, through the application of high-protein defatted peanut flour (DPF) coatings incorporated with and without antioxidants. The control sample without coating, packed in normal atmosphere (control), showed the highest conjugated dienes (CD) increment (from 1.17 on day 0 to 3.60 on day 180). Roasted peanuts without coating, packed in high barrier bags under vacuum, reached the lowest CD at day 180 (1.92). Conjugated trienes and peroxide values were analogous to CD. The control exhibited the greatest decrease in α-tocopherol (from 27.65 mg/100 g on day 0 to 21.32 mg/100 g on day 180) and γ-tocopherol (from 21.91 mg/100 g on day 0 to 14.99 mg/100 g on day 180). 3-Methylpyridine and 2,5-dimethylpyrazine decreased with storage time only for the control, which had the highest increase in oxidized flavor (from 0 on day 0 to 13.30 on day 180), cardboard (from 7.67 on day 0 to 15.23 on day 180), and astringency. The lowest decreases in roasted peanutty scores were seen in coated samples. DPF coatings delayed roasted peanuts oxidation, enhancing their sensory properties and shelf life compared with the control sample. PRACTICAL APPLICATION: Defatted peanut flour (DPF) is a byproduct obtained during peanut oil extraction and is a possible material for edible film preparation. This strategy adds value to the peanut industry by transforming a by-product into a material with the potential to develop biodegradable and economical films. The application of this DPF-based edible coating on the surface of roasted peanuts may have contributed to extent product's shelf life, allowing for coated products to be packaged in lower barrier and less expensive materials. Use of peanut material to coat peanuts avoids the risk of allergen protein cross contamination, which would be highly valuable for the food industry.

Influence of Nontoxic Magnetic Cellulose Nanofibers on Chitosan Based Edible Nanocoating: A Candidate for Improved Mechanical, Thermal, Optical, and Texture Properties

The present work demonstrates the formulation of cellulose nanofiber (CNF) or magnetic cellulose nanofiber (mgCNF) dispersed chitosan-based edible nanocoating with superior mechanical, thermal, optical, and texture properties. The fabrication of mgCNF is successfully achieved through a single-step coprecipitation route, where iron particles get adsorbed onto CNF. The thermal stability of mgCNF is improved considerably, where ∼17% reduction in weight is observed, whereas CNF degrades completely under identical conditions. TGA analysis shows that there is an improvement in thermal stability for both CNF- and mgCNF-reinforced CS nanocoatings, where mgCNF provides more heat dimensional stability than CNF-dispersed CS nanocoatings. Further, the edible nanocoatings are stable even at the temperature of heat treatment such as food sterilization. The mechanical property of the mgCNF-dispersed chitosan (CS) shows a remarkable improvement in tensile strength (57.86 ± 14 MPa) and Young's modulus (2348.52 ± 276 MPa) in comparison to neat CS (6.27 ± 0.7 and 462.36 ± 64 MPa, respectively). To determine the developed materials to be safe for food, the quantification of iron is made by using ICP-MS technique. It is worth mentioning that mgCNF-coated CS helps in improving the texture of cut pineapples in comparison with uncoated pineapple slices under ambient conditions.

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.

Edible Gum-Phenolic-Lipid Incorporated Gluten Films for Food Packaging

The aim of this investigation was to improve the barrier and mechanical properties of gluten films and further explore their application in the packaging of seasonings. The effects of flaxseed gum (FG), oligomeric procyanidins (OPCs), and lauric acid (LA) on the water vapor permeability (WVP), mechanical properties, and peroxide value (POV) were determined. FG and OPCs improved the WVP properties of the gluten films, whereas LA significantly improved the oxygen-barrier properties. The FG/OPCs/LA/GP composite film was then optimized, and the morphological, microstructural, and thermal properties of the composite gluten film were investigated by scanning electron microscopy, atomic force microscopy, surface hydrophobicity analysis; Fourier transform infrared spectroscopy; thermal gravimetric analysis, respectively. The results confirmed that gluten is compatible with FG, OPCs, and LA, thereby leading to the formation of a more uniform, dense, and hydrophobic film. The changes in the preservation properties (appearance, POV, and acid value) of the composite gluten film for oil, salt, and vegetable packaging were also examined. The composite gluten film maintained some degree of seasoning packaging capacity over a 75-day storage period, indicating its potential for uses as a packaging material for seasonings in food production.

PRACTICAL APPLICATION

The edible composite film will be produced in industry according to the data provided in our paper; the film can be used as packaging material for seasonings in food production.

Development of chitosan based extended-release antioxidant films by control of fabrication variables

In this study, mechanical, optical and permeability to water vapor of chitosan containing α-tocopherol film as the function of preparation conditions including concentration of emulsifier and speed of homogenization have investigated. In addition, the effect of above mentioned variables and presence of ethanol as co-surfactant on the release rate of α-tocopherol from chitosan film to fatty food simulant (ethanol 95%) were investigated. Fourier transform infrared spectroscopy and differential scanning calorimetry were employed to analyze the structural and thermal properties of the films. Results showed that the incorporation of α-tocopherol and preparation conditions affected the physical and mechanical properties of the chitosan films. Obtained results indicated that increasing the concentration of Tween 80 increased the release rate of α-tocopherol in the most studied films. Increasing the stirring speed of homogenization and the presence of ethanol considerably decreased the release rate of α-tocopherol at the most film samples. The lowest amount of released antioxidant was 8.6-10% of total incorporated α-tocopherol at the first stages and is obtained when ethanol used during preparation of film forming solution. Our results indicated that the release rate of α-tocopherol could be controlled by changing the stirring speed of homogenization and especially ethanol presence, considerably.