Active chitosan–polyvinyl alcohol films with natural extracts

Fungistatic Films Containing Cinnamon Essential Oil: New Coatings to Preserve the Nutraceutical Content of Avocado Fruit against Fusariosis

Avocadoes are a rich source of nutrients and nutraceuticals that preserve human health. Nevertheless, this fruit is susceptible to phytopathogen infection during the postharvest period causing severe economic losses. Herein, we report on the in situ antifungal assessment of biodegradable films impregnated with the essential oil of Cinnamomum verum (CvEO) as natural fungistatic coatings to extend postharvest quality of Hass avocadoes ( Persea americana cv. Hass). These coatings were evaluated on fruits previously infected with a native strain of Fusarium verticillioides . The cytotoxic assessment of CvEO on F. verticillioides revealed a minimum inhibitory concentration of 0.3 ± 0.0 g L -1 whereas its chemical profiling showed ( E )-cinnamaldehyde (45.9 %) 1,3,8- p -menthatriene (7.9 %) and linalool (6.8 %) as the major bioactive compounds. Four coatings (FC1-FC4) were made using chitosan (1 %) and a diverse quantity of CvEO (0.4-1.3 % w/v). The physicochemical properties demonstrated that the films FC3 and FC4 have the optimal characteristics of a food coating. Avocadoes preserved with the films FC3 and FC4 substantially kept (p < 0.01) fruit firmness and the nutraceutical content of infected avocados at least for 21 d. The results of the present investigation suggest that our hybrid materials are able to conserve basic nutritional parameters such as fiber, protein, reducing sugars, as well as the content of unsaturated fatty acids which are the main nutraceuticals of this fruit.

Ginger Essential Oil as an Active Addition to Composite Chitosan Films: Development and Characterization

The recent interest in food biopackaging is showing an increasing trend, especially in the development of antimicrobial coatings and films. The focus of this study is to assess the potential application of ginger (Zingiber officinale) essential oil (GEO) to polysaccharide films based on chitosan (CHf) and their utilization as an active edible packaging. The films were characterized by different instrumental techniques, and data indicated significant differences (p < 0.05) in the chemical composition of the samples. Forty-seven active compounds from ginger rhizomes were identified in the examined essential oil by gas chromatography mass spectrometer (GC-MS). Fourier transforms infrared spectra (FT-IR) confirmed an interaction between the hydroxyl groups of the phenolic compounds of the essential oil and the amine groups of the bioactive matrix, as shown by the peaks at wavenumbers 1639 cm−1 and 1558 cm−1. X-ray diffraction data suggested a lower crystallinity in the CHf due to the addition of GEO. Differential scanning calorimetric (DSC) analysis revealed that the CHf possessed high thermal stability, especially when different concentrations of GEO were added. The bioactive CHf showed distinct activity against both Gram-positive and Gram-negative bacteria, such as Staphylococcus aureus, Bacillus subtilis, Streptococcus sp., Escherichia coli, Salmonella sp., and Pseudomonas aeruginosa, thus improving the antimicrobial activity to these films. The results provide a comprehensive insight into the importance of films with incorporated EOs as novel types of active food packaging. Antimicrobial food packaging is one of the most promising kinds of active packaging, and acts to reduce, inhibit, or retard any microorganism growth that could contaminate packaged food items.

Improving the Shelf Life of Avocado Fruit against Clonostachys rosea with Chitosan Hybrid Films Containing Thyme Essential Oil

Hass avocadoes are one of the most popular fruits consumed worldwide because of their nutritional and nutraceutical content. Nevertheless, these fruits are susceptible to phytopathogen attacks that decrease fruit quality during the postharvest period. Herein we present the results of the in situ fungistatic activity of four hybrid films (FT1−FT4) manufactured with chitosan and different concentrations of the essential oil of thyme (TvEO). The films were evaluated as biodegradable materials to prevent fruit decay triggered by Clonostachys rosea which is considered an emergent phytopathogen of this crop. The in situ fungistatic strength, spectroscopic properties (FT-IR), optical features (transmittance/opacity), and consistency obtained by microscopic analysis (SEM), indicated that the films FT3 and FT4 possessed the best physicochemical properties to protect Hass avocadoes against the soft rot produced by C. rosea. Avocadoes treated with the films FT3 and FT4 significantly (p < 0.01) conserved fruit firmness and nutritional composition (protein, fat, fiber, and reducing sugars) as well as the nutraceutical content (oleic, palmitoleic, linoleic, and palmitic acids) of infected avocados for 21 days. Our results validate the potential use of the films FT3 and FT4 to prevent the soft rot caused by C. rosea and to improve the shelf life of Hass avocadoes.

Preparation of flexible and UV-blocking films from lignin-containing cellulose incorporated with tea polyphenol/citric acid

Lignin-containing bamboo cellulose, fractionated from a pilot-scale microwave liquefaction of bamboo was dissolved in tetrabutylammonium acetate/dimethyl sulfoxide (TBAA/DMSO) for the fabrication of highly flexible, transparent and UV-blocking films. Tea polyphenol (TP) or citric acid (CA) was added during the dissolving process in order to modify the film's properties. The results showed that the addition of TP obviously improved the elongation at break (triple that of the control) and UV-blocking ability of the films. Both the addition of TP and CA could increase the water contact angle of the films. The films incorporated with TP and CA were much more thermal stable than previously reported similar films. The proposed film fabrication mechanism revealed that stable hydrogen bonds formed between the lignin-cellulose matrix and TP/CA, resulting in the enhancement on the properties of the films. This present study showed that lignin-containing cellulose with the incorporation of TP/CA had great potential in the preparation of films in place of plastic.

Antibacterial Gelidium amansii polysaccharide-based edible films containing cyclic adenosine monophosphate for bioactive packaging

A homogeneous polysaccharide (GAP), with a molecular weight of 51.8 kDa, was isolated from edible red seaweed Gelidium amansii. Composition analysis suggested GAP contained 5.31% sulfate and 17.33% 3,6-anhydro-galactose and was mainly composed of galactose. Furthermore, GAP, as a biopolymer matrix, was used to form the composite films with the small biological molecules cytidine-5'-monophosphate (CMP), adenosine-5'-monophosphate (AMP), and cyclic adenosine monophosphate (cAMP). Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectrum, and X-ray diffraction (XRD) results showed that CMP, AMP, and cAMP interacted with the film substrates and might made films more complex. Notably, the addition of CMP, AMP, and cAMP promoted the light, water vapor, and oxygen barrier ability, surface wettability, mechanical strength, and antimicrobial activity against Gram-negative and -positive bacteria. Finally, GAP-based films composited with cAMP (cAMPF) exhibited the best characteristics were applied to fish packaging and preservation at 4 °C and extended the fish shelf life. All these data suggested the potential value of cAMPF as a functional edible polysaccharide film applied in food industries.

Development and evaluation of Moringa extract incorporated Chitosan/Guar gum/Poly (vinyl alcohol) active films for food packaging applications

The present study contributes the synthesis of active films with the incorporation of moringa extract (ME) into chitosan (CS)/guar gum (GG)/poly(vinyl alcohol) (PVA) matrix (CGPM) by simple solvent casting technique. The effect of ME on the mechanical, thermal, structural and morphological properties of CGPM active films were investigated. ME has shown a marked influence on the optical, thermal properties and swelling behaviour of CGPM active films. The improvement in the tensile strength of CGPM-1 active film (53.7 MPa) was observed compared to control CS/GG/PVA (CGP) film. DSC study revealed that glass transition temperature (Tg) and melting temperature (Tm) decreased with the addition of ME in the CGP matrix, which confirmed the miscibility among the components of active films. There was an improvement in the thermal stability of the CGPM active films. The FTIR study confirmed the molecular interaction between ME and CS/GG/PVA matrix. The XRD analysis showed a decrease in crystallinity with an increase in the ratio of CS for CGPM active films. The CGPM active films were an excellent barrier to UV- light and have exhibited a decrease in moisture adsorption and water solubility compared to CGP control film. The inclusion of ME in the CGP matrix leads to the formation of a dense compact surface, which in turn enhanced hydrophobicity of active films. The CGPM active films showed minimum WVP, OP values and overall migration values were within the limits of 10 mg/dm2. It was also observed that CGPM active films effectively inhibited the growth of E. coli and S. aureus bacteria. These findings suggest CGPM active films are biodegradable, biocompatible, non-toxic and hence can find application as food packaging materials.

Preparation and Evaluation of Chitosan/PVA Based Hydrogel Films Loaded with Honey for Wound Healing Application

In the present study, chitosan/polyvinyl alcohol (PVA)-based honey hydrogel films were developed for potential wound healing application. The hydrogel films were developed by a solvent-casting method and were evaluated in terms of thickness, weight variation, folding endurance, moisture content and moisture uptake. The water vapor transmission rate was found to range between 1650.50 ± 35.86 and 2698.65 ± 76.29 g/m²/day. The tensile strength and elongation at break were found to range between 4.74 ± 0.83 and 38.36 ± 5.39 N, and 30.58 ± 3.64 and 33.51 ± 2.47 mm, respectively, indicating significant mechanical properties of the films. SEM images indicated smooth surface morphology of the films. FTIR, DSC and in silico analysis were performed, which highlighted the docking energies of the protein–ligand complex and binding interactions such as hydrogen bonding, Pi–Pi bonding, and Pi–H bonding between the selected compounds and target proteins; hence, we concluded, with the three best molecules (lumichrome, galagin and chitosan), that there was wound healing potential. In vitro studies pointed toward a sustained release of honey from the films. The antimicrobial performance of the films was investigated against Staphylococcus aureus. Overall, the results signaled the potential application of chitosan/PVA based hydrogel films as wound dressings. Furthermore, in vivo experiments may be required to evaluate the clinical efficacy of honey-loaded chitosan/PVA hydrogel films in wound healing.

Development of multifunctional food packaging films based on waste Garlic peel extract and Chitosan

A sustainable multifunctional food packaging composite film containing waste garlic peel extract (GPE) and Chitosan (CH) was prepared. This film exhibited antimicrobial potential towards Staphylococcus aureus and Klebsiella pneumoniae. GPE/CH films' morphological, physical, and functional properties were compared to those of CH film. Fourier transform infrared showed the interactions through hydrogen bonding between CH and GPE in the blends that improved the polymers' compatibility. Furthermore, X-ray diffraction analysis validated the compatibility between GPE and CH. GPE/CH films exhibited higher thickness and moisture content than the CH film. Remarkably, GPE/CH films showed lower water vapor barrier properties and higher ultra-violet protection and mechanical strength than CH film. Compact surfaces of the GPE infused CH films were unveiled through Scanning electron microscopy. GPE/CH film showed improved thermal stability after the addition of GPE. MTT method's cytotoxicity study manifested that the GPE/CH films are antioxidant and non-cytotoxic, implicating their biocompatibility and non-toxicity. The results suggest that GPE/CH films can find widespread commercial applications like food packaging materials, replacing the commonly used petrochemical plastics.

Incorporation of Natural Blueberry, Red Grapes and Parsley Extract By-Products into the Production of Chitosan Edible Films

The aim of the research was to produce edible packaging based on chitosan with the addition of various concentrations of extracts of blueberry, red grape and parsley marcs. Packaging was made from extrudate extracts, which were subsequently analyzed by physicochemical methods: zeta-potential, gas barrier properties, thickness, water content, solubility, swelling degree, textural properties, total polyphenol content (TPC), polyphenols by high pressure liquid chromatography (HPLC), antioxidant activity, attenuated total reflectance Fourier-Transform spectroscopy (FTIR), antimicrobial activity and determination of migration of bioactive substances. The results indicate that a higher content of plant extracts have a statistically significant (p < 0.05) influence on properties of experimentally produced edible films. Edible films produced with the highest concentrations of red grapes marc extracts showed the most advantageous properties since antimicrobial activity against E. coli were the highest in this kind of produced film. The physical properties of edible films were also improved by the addition of extracts; gas permeability toward oxygen can be defined as advantageous, as can swelling degree, which decreased with higher concentrations of extracts. The research emphasized the possibility to use plant foodstuffs by-products in the production of edible/biodegradable films, helping in the overall sustainability and eco-friendliness of food/package production.

Effects of Peppermint Extract and Chitosan-Based Edible Coating on Storage Quality of Common Carp (Cyprinus carpio) Fillets

Edible coatings have recently been developed and applied to different food matrices, due to their numerous benefits, such as increasing the shelf life of foods, improving their appearance, being vehicles of different compounds, such as extracts or oils of various spices that have antioxidant and antimicrobial activity, as well as being friendly to the environment. The objective of this research was to develop a new edible coating based on chitosan enriched with peppermint extract and to evaluate its effectiveness to inhibit microbial development in vitro and improve both the quality and shelf life of common carp (Cyprinus carpio) during refrigerated storage (4 ± 1 °C). Three treatments were used: edible coating (C + EC), edible coating +, 5% chitosan (C + ECCh) and edible coating + 1.5% chitosan + 10% peppermint (C + ECChP). Prior the coating carp fillets; the antibacterial activity and antioxidant capacity were evaluated in the peppermint extract and coating solutions. After coating and during storage, the following were determined on the fillet samples: microbiological properties, observed for ECP, an inhibition halo of 14.3 mm for Staphylococcus aureus, not being the case for Gram-negative species, for ECCh, inhibition halos of 17.6 mm, 17.1 mm and 16.5 mm for S. aureus, Salmonella typhimurium and Escherichia coli, respectively; for the ECChP, inhibition halos for S. aureus, S. typhimurium and E. coli of 20 mm, 17 mm and 16.8 mm, respectively. For the physicochemical characteristics: an increase in solubility was observed for all treatments during storage, reaching 46.7 mg SN protein/mg total protein for the control, and values below 29.1 mg SN protein/mg total protein (p < 0.05), for fillets with EC (C + EC > C + ECCh > C + ECChP, respectively at the end of storage. For the pH, maximum values were obtained for the control of 6.4, while for the fillets with EC a maximum of 5.8. For TVB-N, the fillets with different CE treatments obtained values (p < 0.05) of 33.3; 27.2; 25.3 and 23.3 mg N/100 g (control > C + E C > C + ECCh > C + ECChP respectively). Total phenolic compounds in the aqueous peppermint extract were 505.55 mg GAE/100 g dried leaves, with 98.78% antioxidant capacity in the aqueous extract and 81.88% in the EC. Biomolecule oxidation (hydroperoxide content) had a significant increase (p < 0.05) in all treatments during storage, 1.7 mM CHP/mg protein in the control, to 1.4 in C + EC, 1.27 in C + ECCh and 1.16 in C + ECChP; TBARS assay values increased in the different treatments during refrigerated storage, with final values of 33.44, 31.88, 29.40 and 29.21 mM MDA/mg protein in the control; C + EC; C + ECCh and C + ECChP respectively. In SDS -PAGE a protective effect was observed in the myofibrillar proteins of fillets with ECChP). The results indicate that the C + ECCh and C + ECChP treatments extend the shelf life of 3–5 days with respect to microbiological properties and 4–5 days with respect to physicochemical characteristics. A reduction in lipid and protein oxidation products was also observed during refrigerated storage. With these findings, this is considered a promising method to increase the shelf life of fish fillets combined with refrigeration and we are able to recommend this technology for the fish processing industry.

Smart biodegradable films based on chitosan/methylcellulose containing Phyllanthus reticulatus anthocyanin for monitoring the freshness of fish fillet

The current work aims to prepare biologically active and pH responsive smart films based on Chitosan (CS)/Methylcellulose (MC) matrix integrated with Phyllanthus reticulatus (PR) ripen fruit anthocyanin. The prepared smart films (CMPR) were fabricated through a cost-effective solvent casting technique. The existences of secondary interactions were confirmed by the FT-IR analysis. The smooth SEM images revealed the miscibility and compatibility of the CS/MC matrix with PR anthocyanin. The incorporation of PR anthocyanin significantly blocked the UV light transmission of the CS/MC films while slight decrease in the transparency was observed. The water solubility, moisture retention capacity, and water vapor transmission rate were significantly enhanced with an increase in the PR anthocyanin content. Additionally, the prepared CMPR smart films showed pink color in acidic pH while yellowish in basic pH solution and further exhibited strong antioxidant activity as well as antibacterial activity against the common foodborne pathogens such as S. aureus, P. aeruginosa, and E. coli. The CMPR smart film also displayed potential result for monitoring the fish fillet freshness at room temperature. The results proclaim that the prepared CMPR smart films could be utilized for quality assurance as well as shelf life extension of the marine food products.

Pineapple peel extract incorporated poly(vinyl alcohol)-corn starch film for active food packaging: Preparation, characterization and antioxidant activity

This research study explores the fabrication of polyvinyl alcohol (PVOH) and corn starch (ST) with pineapple peel extract (PPE) as a natural antioxidant agent, which is an abundant by-product from the food processing industry via casting method. The effects of PPEs concentration (5%, 10%, 15%, and 20%) on the antioxidant capacity, optical, thermal, mechanical, barrier properties, and changes in PVOH-starch molecular structure of PVOH/ST films were investigated. The results revealed that with the increasing concertation of PPEs, prepared films' thickness and water vapor permeability slightly increased. Elongation at break of PVOH/ST films was also enhanced with PPEs concentration. All PPEs incorporated films exhibited enhanced thermal stability as the degradation occurred above 300 °C. The addition of PPE to PVOH/ST films remarkably increased the antioxidant properties. Finally, prepared PVOH/ST/PPE films demonstrated to be a capable material for developing active biodegradable packaging material due to its proven antioxidant activity and mechanical property, which can be helpful in the packaging of food products that gets spoiled due to oxidation reactions.

Development and Characterization of Electrospun Biopapers of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Derived from Cheese Whey with Varying 3-Hydroxyvalerate Contents

In the present study, three different newly developed copolymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 20, 40, and 60 mol % contents in 3-hydroxyvalerate (3HV) were produced by the biotechnological process of mixed microbial cultures (MMCs) using cheese whey (CW), a by-product from the dairy industry, as feedstock. The CW-derived PHBV copolyesters were first purified and then processed by solution electrospinning, yielding fibers of approximately 2 μm in cross-section in all cases. The resultant electrospun PHBV mats were, thereafter, post-processed by annealing at different temperatures, below their maximum of melting, selected according to their 3HV content in order to obtain continuous films based on coalesced fibers, so-called biopapers. The resultant PHBV films were characterized in terms of their morphology, crystallinity, and mechanical and barrier properties to assess their potential application in food packaging. The CW-derived PHBV biopapers showed high contact transparency but a slightly yellow color. The fibers of the 20 mol % 3HV copolymer were seen to contain mostly poly(3-hydroxybutyrate) (PHB) crystals, the fibers of the 40 mol % 3HV copolymer a mixture of PHB and poly(3-hydroxyvalerate) (PHV) crystals and lowest crystallinity, and the fibers of the 60 mol % 3HV sample were mostly made of PHV crystals. To understand the interfiber coalesce process undergone by the materials during annealing, the crystalline morphology was also assessed by variable-temperature both combined small-angle and wide-angle X-ray scattering synchrotron and Fourier transform infrared experiments. From these experiments and, different from previously reported biopapers with lower 3HV contents, all samples were inferred to have a surface energy reduction mechanism for interfiber coalescence during annealing, which is thought to be activated by a temperature-induced decrease in molecular order. Due to their reduced crystallinity and molecular order, the CW-derived PHBV biopapers, especially the 40 mol % 3HV sample, were found to be more ductile and tougher. In terms of barrier properties, the three copolymers performed similarly to water and limonene, but to oxygen, the 40 mol % sample showed the highest relative permeability. Overall, the materials developed, which are compatible with the Circular Bioeconomy organic recycling strategy, can have an excellent potential as barrier interlayers or coatings of application interest in food packaging.

Evaluation of easy-removing antioxidant films of chitosan with Melaleuca alternifolia essential oil

Chitosan - tea tree essential oil (TTEO) films were obtained as a new biodegradable material. Malic acid or lactic acid solvents were evaluated to obtain easy-removing films. The microstructure by SEM and FT-IR, the thermal properties by TGA/DSC, the mechanical properties, the water vapor permeability, the antioxidant (DPPH^• and ABTS^•+) activity and the optical properties of the formulated films were evaluated. A complete dissolution of the film in water was obtained. The elongation to break was higher in the films with malic acid (145.88-317.33%), comparing with those with lactic acid (25.54-44.08%). Chitosan film obtained in malic acid with TTEO showed the highest antioxidant activity. The colour and transparency of the samples did not suffer significant variations by TTEO addition. Films showed good UV-barrier properties, with a slightly improvement by TTEO addition. The films obtained showed a great potential for food packaging applications.

Development and Characterization of Electrospun Fiber-Based Poly(ethylene-co-vinyl Alcohol) Films of Application Interest as High-Gas-Barrier Interlayers in Food Packaging

In the present study, poly(ethylene-co-vinyl alcohol) with 44 mol % ethylene content (EVOH44) was managed to be processed, for the first time, by electrospinning assisted by the coaxial technology of solvent jacket. In addition to this, different suspensions of cellulose nanocrystals (CNCs), with contents ranging from 0.1 to 1.0 wt %, were also electrospun to obtain hybrid bio-/non-bio nanocomposites. The resultant fiber mats were thereafter optimally annealed to promote interfiber coalescence at 145 °C, below the EVOH44 melting point, leading to continuous transparent fiber-based films. The morphological analysis revealed the successful distribution of CNCs into EVOH44 up to contents of 0.5 wt %. The incorporation of CNCs into the ethylene-vinyl alcohol copolymer caused a decrease in the crystallization and melting temperatures (TC and Tm) of about 12 and 7 °C, respectively, and also crystallinity. However, the incorporation of CNCs led to enhanced thermal stability of the copolymer matrix for a nanofiller content of 1.0 wt %. Furthermore, the incorporation of 0.1 and 0.5 wt % CNCs produced increases in the tensile modulus (E) of ca. 38% and 28%, respectively, but also yielded a reduction in the elongation at break and toughness. The oxygen barrier of the hybrid nanocomposite fiber-based films decreased with increasing the CNCs content, but they were seen to remain high barrier, especially in the low relative humidity (RH) regime, i.e., at 20% RH, showing permeability values lower than 0.6 × 10-20 m3·m·m-2·Pa-1·s-1. In general terms, an optimal balance in physical properties was found for the hybrid copolymer composite with a CNC loading of 0.1 wt %. On the overall, the present study demonstrates the potential of annealed electrospun fiber-based high-barrier polymers, with or without CNCs, to develop novel barrier interlayers to be used as food packaging constituents.

Chitosan Edible Films Enhanced with Pomegranate Peel Extract: Study on Physical, Biological, Thermal, and Barrier Properties

In the present study, pomegranate peel extract was used as a reinforcing agent in developing chitosan-based edible film. Different concentrations (0.2 g/mL, 0.4 g/mL, 0.6 g/mL, 0.8 g/mL, and 1.0 g/mL) of pomegranate peel extract were incorporated in chitosan-based edible film. A neat chitosan film was used as a control. This work covers the effect of pomegranate peel extract on the physical, biological, mechanical, thermal, and barrier properties of enriched chitosan-based edible film. The results showed that the thickness (0.142-0.159 mm), tensile strength (32.45-35.23 MPa), moisture (11.23-15.28%), opacity (0.039-0.061%), water (1.32-1.60 g·mm/m2), gas barrier properties (93.81-103.45 meq/kg), phenolic content (5.75-32.41 mg/g), and antioxidant activity (23.13-76.54%) of the films increased with increasing volume fraction of pomegranate peel extract. A higher concentration of incorporated pomegranate peel extracts significantly (p < 0.05) reduced the thermal stability of the film, along with its transparency, solubility, swelling, and color. This work revealed that the incorporation of a higher portion of pomegranate peel extract in chitosan film holds significant (p < 0.05) potential for the increase in biological activities of such films in terms of antioxidant and antimicrobial behavior. The properties of pomegranate peel extract-enriched chitosan films could be an excellent cure for free radicals, whereas they could also inhibit the growth of the foodborne pathogens during the processing and preservation of the food. Further studies are needed for the application of pomegranate peel extract-enriched edible films on food products such as fruits and vegetables in order to extend their storage life and improve the quality and safety of preserved food products.

Novel 2,3-Dialdehyde Cellulose-Based Films with Photodynamic Inactivation Potency by Incorporating the β-Cyclodextrin/Curcumin Inclusion Complex

Antibacterial packaging film mediated by photodynamic inactivation (PDI) is a new concept in food industry. The objective of this study was to fabricate a green 2,3-dialdehyde cellulose (DAC)-based antimicrobial film with PDI potency by incorporating the β-cyclodextrin/curcumin (β-CD/Cur) complex as a photosensitizer. The PDI-mediated films were characterized by evaluating the surface morphology, chemical structure, light transmittance, mechanical properties, photochemical and thermal stability, and water solubility. The results showed that the DAC-CD/Cur films were soluble in water and mechanically strong with a tensile strength of 63.87 MPa and an elongation break of 1.32%, which was attributed to the formation of hydrogen bonds between DAC and β-CD/Cur molecules. Meanwhile, the composite films possessed a good light transmittance but impeded the penetration of ultraviolet light and efficiently delayed the degradation of curcumin. More importantly, the PDI-mediated films exhibited a broad-spectrum ability to kill Listeria monocytogenes, Vibrio parahaemolyticus, and Shewanella putrefaciens in pure culture. Notably, they also potently inactivated these harmful bacteria on ready-to-eat salmon with a maximum of ∼4 Log CFU/g (99.99%) reduction after 60 min irradiation (13.68 J/cm²). Therefore, the PDI-mediated DAC-CD/Cur films are novel and promising antimicrobial food packaging films in food industry.

Characterization of a flavonol-rich antioxidant fraction from Spondias purpurea L. pulp and the effect of its incorporation on cellulose acetate-based film

BACKGROUND

Active packaging containing natural flavonoid has recently emerged as a result of its potential to inhibit the oxidation of foods by interacting with it and/or its surrounding environment, with the aim of counteracting oxidation reactions and extending the shelf-life of foods. The plant Spondias purpurea L. is widely found in northeastern Brazil and is known to contain bioactive flavonoids. The present study aimed to obtain a flavonoid-rich fraction from the pulp of S. purpurea L. and incorporate it into the cellulose acetate film to obtain biodegradable films with antioxidant properties.

RESULTS

The fractionation in SiO₂ open-column chromatography of the S. purpurea pulp crude extract furnished an antioxidant active fraction containing the flavonols quercetin 3-O-rutinoside and kaempferol 3-O-rutinoside as the major compounds. This active fraction was incorporated (10, 20 and 30 g kg^-1 ) into the substance produced with the casting method for cellulose acetate films. The films produced were characterized concerning mechanical properties, water vapor permeability (WVP) and antioxidant activity.

CONCLUSION

The incorporation of the active flavonoid fraction from S. purpurea in the cellulose acetate films decreases WVP and elongation at break, at the same time as increasing antioxidant activity, tensile strength and elastic modulus. Thus, the S. purpurea pulps may be an alternative as a source of antioxidants for use in cellulose acetate films. © 2020 Society of Chemical Industry.

High-Oxygen-Barrier Multilayer Films Based on Polyhydroxyalkanoates and Cellulose Nanocrystals

This study reports on the development and characterization of organic recyclable high-oxygen-barrier multilayer films based on different commercial polyhydroxyalkanoate (PHA) materials, including a blend with commercial poly(butylene adipate-co-terephthalate) (PBAT), which contained an inner layer of cellulose nanocrystals (CNCs) and an electrospun hot-tack adhesive layer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from cheese whey (CW). As a result, the full multilayer structures were made from bio-based and/or compostable materials. A characterization of the produced films was carried out in terms of morphological, optical, mechanical, and barrier properties with respect to water vapor, limonene, and oxygen. Results indicate that the multilayer films exhibited a good interlayer adhesion and contact transparency. The stiffness of the multilayers was generally improved upon incorporation of the CNC interlayer, whereas the enhanced elasticity of the blend was reduced to some extent in the multilayer with CNCs, but this was still much higher than for the neat PHAs. In terms of barrier properties, it was found that 1 µm of the CNC interlayer was able to reduce the oxygen permeance between 71% and 86%, while retaining the moisture and aroma barrier of the control materials.

Biodegradable Chitosan Films with ZnO Nanoparticles Synthesized Using Food Industry By-Products—Production and Characterization

This work aimed to produce bionanocomposites of chitosan incorporated with zinc oxide nanoparticles (ZnO NPs) synthesized using food industry by-products and to characterize them. Such nanoparticles are highlighted due to their low cost, antimicrobial activity, accessibility, and sustainability synthesis. Four different levels of ZnO NPs (0, 0.5, 1.0, and 2.0% w/w of chitosan) were tested, and the bionanocomposites were characterized in terms of their hydrophobicity, mechanical, optical, and barrier properties. Overall, the incorporation of ZnO NPs changed the composites from brittle to ductile, with enhanced elongation at break and reduced Young Modulus and tensile strength. Thus, ZnO NPs acted as plasticizer, turning the films more flexible, due to the presence of organic compounds on the NPs. This also favored permeability of oxygen and of water vapor, but the good barrier properties were maintained. Optical properties did not change statistically with the ZnO NPs incorporation. Thus, the characterization presented in this paper may contribute to support a decision on the choice of the material’s final application.

Development of an eco-friendly biodegradable plastic from jack fruit peel cellulose with different plasticizers and Boswellia serrata as filler

Pure nanocellulose was extracted from agricultural waste material namely jackfruit (Artocarpus heterophyllus) peel through acid hydrolysis. The extraction method utilizes soapnut solution as an eco-friendly bleaching agent in order to avoid environment polluting chlorinated chemicals. Various thin films were prepared by solvent casting nanocellulose and different plasticizers namely glycerol, polyethylene glycol, polyvinyl alcohol, triethyl citrate along with novel filler, Boswellia serrata commonly known as frankincense. Thin films were characterized by FT-IR, XRD and the surface modifications were investigated using FESEM. The physical, mechanical, thermal properties and biodegradability of the film were also reported. The surface morphology was improved by different plasticizers and a self-assembly was obtained due to more stable hydrogen bonding between the nanocellulose, plasticizers and filler during the film formation. Thermal investigations of plasticizers/Boswellia serrata incorporated thin films revealed an increase in glass transition temperature of nanocellulose. Results indicate that these films are biodegradable and compostable in nature and could be used as substitute for petroleum derived plastics.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Blends of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) with Fruit Pulp Biowaste Derived Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate-co-3-Hydroxyhexanoate) for Organic Recycling Food Packaging

In the present study, a new poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) [P(3HB-co-3HV-co-3HHx)] terpolyester with approximately 68 mol% of 3-hydroxybutyrate (3HB), 17 mol% of 3-hydroxyvalerate (3HV), and 15 mol% of 3-hydroxyhexanoate (3HHx) was obtained via the mixed microbial culture (MMC) technology using fruit pulps as feedstock, a processing by-product of the juice industry. After extraction and purification performed in a single step, the P(3HB-co-3HV-co-3HHx) powder was melt-mixed, for the first time, in contents of 10, 25, and 50 wt% with commercial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Thereafter, the resultant doughs were thermo-compressed to obtain highly miscible films with good optical properties, which can be of interest in rigid and semirigid organic recyclable food packaging applications. The results showed that the developed blends exhibited a progressively lower melting enthalpy with increasing the incorporation of P(3HB-co-3HV-co-3HHx), but retained the PHB crystalline morphology, albeit with an inferred lower crystalline density. Moreover, all the melt-mixed blends were thermally stable up to nearly 240 °C. As the content of terpolymer increased in the blends, the mechanical response of their films showed a brittle-to-ductile transition. On the other hand, the permeabilities to water vapor, oxygen, and, more notably, limonene were seen to increase. On the overall, this study demonstrates the value of using industrial biowaste derived P(3HB-co-3HV-co-3HHx) terpolyesters as potentially cost-effective and sustainable plasticizing additives to balance the physical properties of organic recyclable polyhydroxyalkanoate (PHA)-based food packaging materials.

Eco-friendly natural extract loaded antioxidative chitosan/polyvinyl alcohol based active films for food packaging

Nowadays, biodegradable antimicrobial packaging materials draw substantial attention and are considered one of the preferred emerging technologies to be used in the food industry. In this study, we have reported developing a two-component, chitosan (CS) and polyvinyl alcohol (PVA) based films loaded with natural extract of Ocimum tenuiflorum via solvent casting technique. Experimental results showed that all the components were well dispersed, resulting in complete homogenous films. FTIR-ATR spectral analysis indicated strong interaction between the film matrix components, which also gets reflected by the films' physical properties. Transparent biodegradable films have resulted from the mixture and incorporation of the natural agent/extracts influenced light barrier, water resistance, moisture content (9.89-9.01%), and DPPH radical scavenging properties (antioxidant value ~41.1%) of the CS/PVA films. Therefore, this natural extract containing transparent CS/PVA-based films promises to be used in the food industry as packaging material to enhance food safety.

Trends in Chitosan as a Primary Biopolymer for Functional Films and Coatings Manufacture for Food and Natural Products

Some of the current challenges faced by the food industry deal with the natural ripening process and the short shelf-life of fresh and minimally processed products. The loss of vitamins and minerals, lipid oxidation, enzymatic browning, and growth of microorganisms have been the main issues for many years within the innovation and improvement of food packaging, which seeks to preserve and protect the product until its consumption. Most of the conventional packaging are petroleum-derived plastics, which after product consumption becomes a major concern due to environmental damage provoked by their difficult degradation. In this sense, many researchers have shown interest in edible films and coatings, which represent an environmentally friendly alternative for food packaging. To date, chitosan (CS) is among the most common materials in the formulation of these biodegradable packaging together with polysaccharides, proteins, and lipids. The good film-forming and biological properties (i.e., antimicrobial, antifungal, and antiviral) of CS have fostered its usage in food packaging. Therefore, the goal of this paper is to collect and discuss the latest development works (over the last five years) aimed at using CS in the manufacture of edible films and coatings for food preservation. Particular attention has been devoted to relevant findings in the field, together with the novel preparation protocols of such biodegradable packaging. Finally, recent trends in new concepts of composite films and coatings are also addressed.

Aging Studies on Food Packaging Films Containing β-Cyclodextrin-Grafted TiO2 Nanoparticles

Polymeric materials, such as polyvinyl alcohol (PVA) and ethylene–PVA copolymers (EVOH) are widely used in the food sector as packaging materials because of their excellent properties. TiO₂ nanoparticles (NPs) show photocatalytic activity; when added to the aforementioned polymers, on the one hand, they are expected to provide bactericidal capacity, whereas on the other hand, they could favor nanocomposite degradation. These types of nanoparticles can be derivatized with cyclodextrin macromolecules (CDs), which can act as food preservative carriers, increasing the packaging food protective properties. In this work, films containing β-Cyclodextrin (βCD)-grafted TiO₂ nanoparticles and PVA or EVOH were prepared. Regarding the photocatalytic activity of the nanoparticles and the possible environmental protection, accelerated aging tests for PVA, EVOH, and their composites with cyclodextrin-grafted TiO₂ nanoparticle (NP) films were performed by two methods, namely, stability chamber experiments at different conditions of temperature and relative humidity and UV light irradiation at different intensities. After analyzing the systems color changes (CIELAB) and Fourier transform infrared spectroscopy (FTIR) spectra, it was observed that the film degradation became more evident when increasing the temperature (25–80 °C) and relative humidity percentage (28–80%). There was no significant influence of the presence of CDs during the degradation process. When irradiating the films with UV light, the largest color variation was observed in the nanocomposite films, as expected. Moreover, the color change was more relevant with increasing NP percentages (1–5%) due to the high photocatalytic activity of TiO₂. In addition, films were characterized by FTIR spectroscopy and variation in the signal intensities was observed, suggesting the increase of the material degradation in the presence of TiO₂ NPs.

Hydroxy citric acid cross-linked chitosan/guar gum/poly(vinyl alcohol) active films for food packaging applications

The present work aims to prepare Chitosan (CS)/Guar gum (GG)/Poly(vinyl alcohol) (PVA) cross-linked with Hydroxy citric acid (HCA) (CGPH active film) by solvent casting technique. The influence of HCA on different CS/PVA ratio (1:3, 1:1, 3:1) in presence of the fixed amount of GG (0.2%) was investigated. The analysis of the results showed that the addition of HCA to the different ratio of CS/PVA increased the degradation temperature and improved the mechanical properties of CGPH active films. FTIR spectra and XRD analysis revealed strong interactions among the components of CGPH active films. The analysis of SEM images and water contact angle suggested a compact, dense film surface with hydrophobic nature. Further, all the active films have shown a decrease in water vapour permeability (WVP) and acted as a barrier to UV-light. CGPH active films effectively inhibited the growth of S. aureus and E. coli bacteria. With all these features the CGPH active films can find application in food packaging.

Ultraviolet blocking and antioxidant polyvinyl alcohol films incorporated with baicalin extraction from Scutellaria baicalensis Georgi

Baicalin, an active flavonoid ingredient of Scutellaria baicalensis Georgi, was extracted by heat reflux extraction and showed the same significance UV absorption property with standard baicalin. Active films were prepared from polyvinyl alcohol (PVA) containing baicalin extract by casting method. The effect of baicalin extracts on the UV-blocking, optical, antioxidant property, water vapor permeability, swelling and mechanical properties of the films were studied. UV–vis transmittance spectra showed that PVA films incorporated with baicalin extract blocked ultraviolet light range from 280–400 nm even with low concentration of baicalin (0.5 wt%) and maintain the high transparency in visible spectrum. The outstanding UV-blocking properties of PVA films incorporated with baicalin extract were also confirmed by Rhodamine B degradation. Baicalin conferred antioxidant properties to PVA films as determined by DPPH radical scavenging activity. Due to the interaction between hydroxy groups of baicalin and PVA molecule, water vapor permeability, swelling and elongation at break of the films were decreased accompanied with the increasing in tensile strength and Young’s modulus. FTIR reveal that the interaction between PVA molecules was significant changed by the introduction of baicalin. These results suggest that PVA film incorporated with baicalin extract can be used for the development of functional protective film.

Emergency Food Product Packaging by Pectin-Based Antimicrobial Coatings Functionalized by Pomegranate Peel Extracts

Emergency food products (EFPs) or energy bars are used in critical situations, such as natural disasters, to promote crisis management. EFPs require sophisticated packaging strategies. Edible coatings incorporated with natural antimicrobial agents could be considered as active packaging materials for increasing EFP safety. In this study, pectin-based coatings incorporated with pomegranate peel extracts were used to protect energy bars. Initially, total phenolic contents and antimicrobial and antioxidant properties of aqueous and ethanolic pomegranate peel extracts (PPEs) were determined. Also, PPEs were analyzed by HPLC. In the next step, the extracts were incorporated into the matrix of edible coatings as active substances. The sensory properties and microbial contamination of coated energy bars were investigated during 30 days of storage. Sixteen phenolic substances were detected in the extracts with gallic acid, ellagic acid, caffeic acid, coumaric acid, and quercetin as major ingredients. The ethanolic extract exhibited higher concentrations for all phenolic compounds. The results indicated that the ethanolic extract showed inhibitory effects on S. aureus and E. coli at concentrations of 30 and 50 mg/ml, and the aqueous extract's inhibitory effects were observed at concentrations of 50 and 80 mg/ml, respectively. The antioxidant and antibacterial effects could be attributed to high phenolic content and a combination of different substances. Microbial and sensory tests performed on coated energy bars showed that the active coatings were able to control and reduce the population of microorganisms during storage without adversely affecting sensory properties.

Preparation and characterization of gelatin/chitosan/3-phenylacetic acid food-packaging nanofiber antibacterial films by electrospinning

In this study, antibacterial nanofiber films were prepared by electrospinning gelatin, chitosan, and 3-phenyllactic acid (PLA). The addition of PLA improved the microstructures of the nanofibers, and the nanofiber films (GCP-1 and GCP-2) had uniform and continuous structures with a diameter range of 40--70 nm when the PLA concentrations in the polymers were 1% and 2%. Under acidic conditions, chitosan and PLA interacted and formed hydrogen bonds, which decreased the crystallinity of the nanofiber films. The GCP-2 nanofiber film had the best thermal stability, water stability, and water vapor permeability. Compared with the control GCP-0 film, the four nanofiber films with PLA (GCP-1, GCP-2, GCP-3, and GCP-4) had more effective antibacterial effects, and GCP-2 film reduced approximately 4 log CFU/mL of Salmonella enterica Enteritidis and Staphylococcus aureus in 30 min. Results suggested that the GCP-2 nanofiber film mat can be used as an active food packaging.

Innovations in Smart Packaging Concepts for Food: An Extensive Review

Innovation in food packaging is mainly represented by the development of active and intelligent packing technologies, which offer to deliver safer and high-quality food products. Active packaging refers to the incorporation of active component into the package with the aim of maintaining or extending the product quality and shelf-life. The intelligent systems are able to monitor the condition of packaged food in order to provide information about the quality of the product during transportation and storage. These packaging technologies can also work synergistically to yield a multipurpose food packaging system. This review is a critical and up-dated analysis of the results reported in the literature about this fascinating and growing field of research. Several aspects are considered and organized going from the definitions and the regulations, to the specific functions and the technological aspects regarding the manufacturing technologies, in order to have a complete overlook on the overall topic.