Films For Food Packaging Applications Research Articles

Starch/tea polyphenols nanofibrous films for food packaging application: From facile construction to enhance mechanical, antioxidant and hydrophobic properties

Starch based food packaging has been receiving increasing attention. However, the inherent poor properties of starch restrict its practical applications in the versatile material science field. In this study, a fast, simple, and environmentally friendly route to construct polyfunctional starch/tea polyphenols nanofibrous films (STNFs) by one-step temperature-assisted electrospinning was developed. The effects of introduction of tea polyphenols (TP) on the mechanical and antioxidant activity of STNFs were comprehensively investigated. Results of ABTS·+ free radical scavenging assay showed that the antioxidant activity of STNFs was endowed by addition of TP with optimum mechanical properties confirmed by tensile test. More interestingly, the hydrophobicity of STNFs was improved dramatically with increasing cross-linking time as indicated by water contact angle (WCA) measurement showing no effect on the antioxidant activity of the films. The results of this work offer a major step forward to promote functional starch-based materials for sustainable application in food packaging.

Development of quaternary nanocomposites made up of cassava starch, cocoa butter, lemongrass essential oil nanoemulsion, and brewery spent grain fibers.

We report on production of novel quaternary nanocomposite films based on thermoplastic starch (TPS, 8% w/v) derived from cassava, cocoa butter, (CB, 30%wt.%), and lemongrass essential oil (LEO, 1:1) nanoemulsions reinforced with different concentrations of brewery spent grain (BSG, 5 or 10wt.%) fibers, by continuous casting. The chemical composition, the morphological, thermal, mechanical properties, film barrier, biodegradability in the vegetable compound, in addition to the application in chocolates, have been widely studied. The addition of CB, LEO, and BSG caused relevant changes in the starch-based films, such as increased extensibility (from 2.4-BSG5 to 9.4%-BSG10) and improved barrier to moisture (2.9 and 2.4g.mm.kPa-1 .h-1 .m-2 ). Contrastingly, the thermal stability of the starch film was slightly decreased. The biodegradability of the herein developed quaternary nanocomposite films was the same as that of TPS films, eliminating concerns on the supplementation with active ingredients that are expected to have some biocidal effect. Despite checking antimicrobial activity only by contact under the biocomposites, chocolates packed with the films were well accepted by consumers, especially the samples of white chocolate stored in the BSG5 biocomposite. Overall, this new approach towards quaternary active, biodegradable films produced in a pilot-scale lamination unit was successful in either improving or at least maintaining the essential properties of TPS-based films for food packaging applications, while providing them with unique features and functionalities. PRACTICAL APPLICATION: This contribution relates to new approach toward quaternary films produced in a pilot-scale lamination unit. It relates to sustainability as it is both biodegradable and based on plant biomass, as well as produced via a clean, through high-yield process. The four components of the edible films we developed provide it with good in properties performance, as both a passive barrier (i.e. purely physical), and active, related to the sensory attributes of food, essential to be applied in food packaging. The valorization of a BSG also adds to the relevance of our contribution within the circular bioeconomy framework.

Physicochemical and Antibacterial Evaluation of Poly (Vinyl Alcohol)/Guar Gum/Silver Nanocomposite Films for Food Packaging Applications

In this study, we prepared Poly (vinyl alcohol) (PVA)/Guar gum (GG) based nanocomposite films with a different weight ratio of silver nanoparticles (AgNPs) via in situ approach using GG itself as a reducing agent and PVA as a capping as well as stabilizing agent at room temperature. The in situ synthesized AgNPs in the PVA/GG matrix was confirmed by surface plasmon resonance (420–450 nm) and SEM-EDAX analysis. The average size of AgNPs was found to be 10 nm determined by XRD. The light transmittance is greatly influenced by the AgNPs. At an optimal concentration of AgNPs (6.8 mg), PVA/GG/Ag nanocomposite films showed improved tensile properties (Ts—23.93 MPa) and the water vapor transmission rate. The incorporation of AgNPs has significantly enhanced the hydrophobicity (~ 77%) as well as the thermal stability (~ 61.39%) of the PVA/GG film. The overall migration rate of the nanocomposite films with the three food simulants was shown significantly below the permitted limit of 10 mg/dm2. Further PVA/GG/Ag nanocomposite films showed a lower soil burial degradation rate than PVA/GG film and good antibacterial properties against environmental microorganisms such as S. aureus and E. coli bacteria. The results suggest that the prepared films can be used as promising food packaging materials.

Liposomal Encapsulation of Carvacrol to Obtain Active Poly (Vinyl Alcohol) Films.

Lecithins of different origins and compositions were used for the liposomal encapsulation of carvacrol within the framework of the development of active films for food packaging. Liposomes were incorporated into aqueous polymeric solutions from fully (F) and partially (P) hydrolysed Poly (vinyl alcohol) (PVA) to obtain the films by casting. The particle size distribution and ζ-potential of the liposomal suspensions, as well as their stability over time, were evaluated. Liposomal stability during film formation was analysed through the carvacrol retention in the dried film and the film microstructure. Subtle variations in the size distributions of liposomes from different lecithins were observed. However, the absolute values of the ζ-potential were higher (−52, −57 mV) for soy lecithin (SL) liposomes, followed by those of soy lecithin enriched with phosphatidylcholine (SL-PC) (−43, −50 mV) and sunflower lecithin (SFL) (−33, −38 mV). No significant changes in the liposomal properties were observed during the study period. Lyotropic mesomorphism of lipid associations and carvacrol leakage occurred to differing extents during the film drying step, depending on the membrane lipid composition and surface charge. Liposomes obtained with SL-PC were the most effective at maintaining the stability of carvacrol emulsion during film formation, which led to the greatest carvacrol retention in the films, whereas SFL gave rise to the least stable system and the highest carvacrol losses. P-PVA was less sensitive to the emulsion destabilisation due to its greater bonding capacity with carvacrol. Therefore, P-PVA with carvacrol-loaded SL-PC liposomes has great potential to produce active films for food packaging applications.

Cellulose nanofibrils reinforced xylan-alginate composites: Mechanical, thermal and barrier properties

Cellulose nanofibrils (CNFs) can be used as an effective reinforcement material for biopolymer films intended for food packaging applications. The aim of this study was to improve the mechanical and barrier properties of xylan-alginate films by incorporating CNFs into the xylan-alginate matrix. CNFs was produced from maize stalk waste residues through a combination of chemical and mechanical treatment. The CNFs was incorporated into the xylan-alginate matrix between 1 and 10 wt%. The suitability of the CNFs reinforced composite films for food packaging applications was investigated by testing the mechanical, thermal and optical properties as well as the moisture sorption, solubility and water vapour permeability of the films. The CNFs produced had fibre diameters between 10 and 80 nm and transmission electron microscopy images showed that the CNFs were highly entangled hence forming a web like structure. It was found that the incorporation of CNFs into the xylan-alginate matrix increased the tensile strength and Young's modulus of the films. The incorporation of CNFs improved the WVP of the films but did not show any significant effect on the thermal properties of the films.

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

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

Active natural-based films for food packaging applications: The combined effect of chitosan and nanocellulose

This work aimed to evaluate the potential of chitosan/cellulose nanocrystals (CNC) films to be used as active pads for meat packages to prolong its shelf-life and preserve its properties over time. Several CNC concentrations (5, 10, 25, and 50 wt%) were tested and the films were produced by solvent casting. The developed samples were characterized by ATR-FTIR, TGA, FESEM, and XRD. The transparency, antimicrobial, barrier and mechanical properties were also assessed. Finally, the films' ability to prolong food shelf-life was studied in real conditions using chicken meat.CNC incorporation improved the thermal stability and the oxygen barrier while the water vapor permeability was maintained. An enhancement of mechanical properties was also observed by the increase in tensile strength and Young's modulus in chitosan/CNC films. These films demonstrated bactericidal effect against Gram-positive and Gram-negative bacteria and fungicidal activity against Candida albicans. Lastly, chitosan-based films decreased the growth of Pseudomonas and Enterobacteriaceae bacteria in meat during the first days of storage compared to commercial membranes, while chitosan/CNC films reduced the total volatile basic nitrogen (TVB-N), indicating their efficiency in retarding meat's spoilage under refrigeration conditions.This work highlights the great potential of natural-based films to act as green alternatives for food preservation.

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.

Influence of plasticizers on the compostability of polylactic acid

<p>Poly(lactic acid) (PLA) has gained considerable attention as an interesting biobased and biodegradable polymer for film for food packaging applications, due to its many advantages such as biobased nature, high transparency and inherent biodegradable/compostable character. With the dual objective to improve PLA processing performance and to obtain flexible materials, plasticizer are use as strategy for extending PLA applications as compostable film for food packaging applications. Several plasticizers (i.e.: citrate esters, polyethylene glycol (PEG), oligomeric lactic acid (OLA), etc.) as well as essential oils and maleinized and/or epoxidized seed oils are widely used for flexible PLA film production. This article reviews the most relevant compostable PLA-plasticized flexible film formulations with an emphasis on plasticizer effect on the compostability rate of PLA polymeric matrix with the aim to get information of the possibility to use plasticized PLAbased formulatios as compostable films for sustainable industrial packaging production.</p>

Strategies to Improve the Properties of Amaranth Protein Isolate-Based Thin Films for Food Packaging Applications: Nano-Layering through Spin-Coating and Incorporation of Cellulose Nanocrystals.

In this work, two different strategies for the development of amaranth protein isolate (API)-based films were evaluated. In the first strategy, ultrathin films were produced through spin-coating nanolayering, and the effects of protein concentration in the spin coating solution, rotational speed, and number of layers deposited on the properties of the films were evaluated. In the second strategy, cellulose nanocrystals (CNCs) were incorporated through a casting methodology. The morphology, optical properties, and moisture affinity of the films (water contact angle, solubility, water content) were characterized. Both strategies resulted in homogeneous films with good optical properties, decreased hydrophilic character (as deduced from the contact angle measurements and solubility), and improved mechanical properties when compared with the neat API-films. However, both the processing method and film thickness influenced the final properties of the films, being the ones processed through spin coating more transparent, less hydrophilic, and less water-soluble. Incorporation of CNCs above 10% increased hydrophobicity, decreasing the water solubility of the API films and significantly enhancing material toughness.

Thermoplastic starch and poly(vinyl alcohol) blends centered barrier film for food packaging applications

This study explores the potential use of a Thermoplastic Starch (TPS)/Polyvinyl Alcohol (PVOH) blend as an alternative center-layer material to ethylene vinyl alcohol (EVOH) in food packaging films. Multi-layer films consisting of a TPS/PVOH blend center-layer sandwiched between low-density polyethylene (LDPE) outer layers were prepared in a co-extruded blown film line. Middle-layer blend concentration of TPS was varied from 0 to 100 wt% and the barrier and mechanical properties were characterized. Films with center layer blends containing 25 and 75 wt% TPS exhibited similar oxygen barrier properties to neat EVOH. Moreover, multi-layer films containing 25 wt% TPS center-layers showed the highest tensile strength and dart impact value among all blends and this was attributed to an enhanced interaction between blend constituents. The study suggests that the blends containing either 25 or 75 wt% TPS could serve as alternative barrier layers due to their relatively low material cost, good oxygen barrier performance and adequate material properties.

Influence of NiO Supported Silica Nanoparticles on Mechanical, Barrier, Optical and Antibacterial Properties of Polylactic Acid (PLA) Bio Nanocomposite Films for Food Packaging Applications

This study aimed to prepare the nickel oxide supported on silica nanoparticles (NiO NPs) incorporated polylactic acid (PLA) bio nanocomposite films of various concentrations (0.25, 0.5. 0.75, 1 wt%) and study the resultant properties of NiO on the tensile, barrier, surface color, opacity and antibacterial properties for food packaging applications. The maximum tensile strength of 16.4 MPa was obtained at 1 wt% of the prepared biocomposite film. The barrier properties like oxygen transmission rate and water vapor transmission rate were significantly reduced and showed a better value of 841.20 (cc / (m2. day. atm)) and 3.96 (g/ m2 /day) on 1 wt% of NiO. The incorporation of NiO NPs increased the surface color (L*, a*, b*) and the opacity values were bio nanocomposite films. Also, the PLA / NiO bio nanocomposite films showed good antibacterial activity against gram-positive (L.monocytogenes) and gram-negative bacteria (Salmonella). Therefore, the prepared bio nanocomposite films could be used as an excellent packaging material for food packaging applications.

Synthesis and characterisation of starch/agar nanocomposite films for food packaging application.

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8-15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram-negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.

Development of TiO2 catalyzed HTPB based oxygen scavenging films for food packaging applications

The purpose of this study was to investigate the oxygen scavenging properties of TiO2 catalyzed hydroxyl terminated polybutadiene (HTPB) blends with low density polyethylene (LDPE) and polylactic acid (PLA) matrices, prepared by melt extrusion. SEM images performed on prepared cast films demonstrated homogenously dispersed domains of HTPB in both matrices. In LDPE/HTPB blends, a hydrocarbon wax was added to overcome the undesirable phase separation.The oxygen absorption measurements successfully verified the photocatalytic activity of TiO2 to catalyze the oxidation of HTPB which led to a proper oxygen scavenging efficiency in our blends. The oxygen absorption of the blends increased by the addition and increasing the composition of TiO2 catalyzed HTPB. The final absorption reached about 30 and 27 cc/g after 30 days for the films containing 10 and 13 wt% HTPB in LDPE and PLA matrices, respectively.

Rutile TiO2 integrated zwitterion polyurethane composite films as an efficient photostable food packaging material

Zwitterion polyurethanes (ZPU) are used for non-fouling and antimicrobial surfaces but their sensitive nature under ultra-violet (UV) radiations limits the requirements of engineering materials. Herein, ZPU is successfully synthesized and then prepared different TiO2/ZPU composites, aiming to increase the service life of ZPU and to form active film for food packaging applications. The thermo-mechanical results revealed that the 4% TiO2/ZPU sample exhibits better performance, as evidenced through tensile testing and surface morphology analysis. The UV–Vis spectra results indicated that the rutile TiO2 nanoparticles can enhance the UV absorption and visible light reflectance, decreasing photoaging properties of composites thereby prolonging its shelf life. Moreover, scanning electron microscopy (SEM) observation after 5 h irradiation of UV light confirmed the photostability of TiO2/ZPU composite film. Further, the antioxidant ability of ZPU is increased from 51% to 71% with TiO2. The results of antimicrobial activity of TiO2/ZPU demonstrate strong bacterial growth inhibition against E. coli that regards its suitability for food and other packaging applications. Besides, the food preservation ability is monitored by visual changes of tomato fruit. In essence, we anticipate that the TiO2/ZPU composite films possessed all expected features to be considered as photostable material for food packaging.

Reinforcement of Na-Alginate Based Films with Carrot Juice Processing Wastes

In this study, Na-alginate based films were produced with the addition of cellulosic fibres from carrot juice processing wastes for employment of agricultural wastes as reinforcing agent in biobased films for food packaging purposes. These films were characterized by water vapour permeability WVP , colour, XRD, transmittance and the SEM analysis. The WVP of the Na-alginate based films were significantly decreased upon the addition of carrot fibre at each level of incorporation 1% and 5%, w/w on alginate basis . Depending on the colour values, the obtained films were highly transparent, but the yellowness of the 5% carrot fibre film CFF was significantly higher than control 0% CFF and 1% CFF samples p< 0.05 . The transmittance of control film was higher than the carrot fibre added films, since the lower light impermeability of 5% CFF was notable in the visual observations and the SEM images. The results revealed that the obtained carrot fibre cellulosic material may be used as reinforcing agent in biobased films for food packaging applications.

Development of active agents filled polylactic acid films for food packaging application

The growing global awareness for environmental protection has inspired the exploration on producing active packaging films from bio-based materials. In present work, three types of active agents were studied by incorporating thymol(T), kesum(K), and curry(C) (10% wt.) into polylactic acid (PLA) to produce PLA-10T, PLA-10K, and PLA10-C packaging films via solvent casting method. The morphology, functional chemistry, thermal stability, permeability, and antimicrobial properties were evaluated for PLA films. Functional chemical analysis confirmed the presence of interfacial bonding between aromatic groups of active agents and PLA carbonyl group. PLA-10K exhibited the highest thermal resistance comparing to PLA-10T and PLA-10C while water vapor barrier was enhanced after incorporation of active agents. Qualitative observation had indicated that chicken meat could be preserved in the active films until 15 days, while odourless and firm texture properties retained in food sample. For disc diffusion assay (in vitro), it showed positive results against Gram-positive bacteria (Staphylococcus aureus) whereas with negative results against Gram-negative bacteria (Escherichia coli) and Aspergillus Brasiliensis due to embedded active agents within PLA matrix. We concluded that produced active agents filled PLA films potential to use in food packaging application to enhance the shelf life of meats, fruits and vegetables product.

Effect of carvacrol in the properties of films based on poly (vinyl alcohol) with different molecular characteristics

Poly (vinyl alcohol) (PVA) is a hydrophilic linear polymer obtained from the controlled hydrolysis of poly (vinyl acetate) (PVAc). The molecular weight (Mw) and degree of hydrolysis (DH) of PVA are considered relevant in both the functionality of the polymer and its capacity for film formation. This study analysed the influence of the Mw and DH of PVA on both the film's ability to incorporate carvacrol (CA), for the purposes of obtaining active films for food packaging application, as well as on the film microstructure, thermal behaviour and its functional properties as packaging material. CA was incorporated at 5 and 10 g/100 g polymer by emulsification in the polymer-water solutions, while the films were obtained by casting. The higher Mw polymer provided films with a better mechanical performance but less CA retention and a more heterogeneous structure. In contrast, low Mw, partially acetylated PVA gave rise to homogenous films with a higher CA content that increased the mechanical resistance and stretchability of the films. The melting temperature of this polymer with acetyl groups was lower than the degradation temperature, which makes thermoprocessing feasible.

Physico-chemical and functional properties of rutin induced chitosan/poly (vinyl alcohol) bioactive films for food packaging applications

Rutin induced Chitosan/Poly (vinyl alcohol) bioactive films were developed by using solvent casting technique. The effect of various concentrations (0.2, 0.4 and 0.6%) of rutin on physico-chemical and functional properties of bioactive films were studied and analysis results indicated that presence of rutin improved the barrier to UV-light, WVP, OTR, water resistance, water solubility and thermal properties. The results of water contact angle, FTIR and SEM showed that addition of rutin increased the network compactness of the bioactive films which resulted from strong intermolecular interactions through hydrogen bonding. Stress-strain curves demonstrated that the incorporation of 0.6% of rutin gives maximum values of TS, %EB and YM as 54 ± 1 MPa, 51 ± 1.5% and 1423 ± 13.2 MPa, respectively. Bioactive films showed strong antimicrobial activity against E. coli and S. aureus bacteria. The overall migration of components of bioactive films in different food simulants were within the permitted limits of 10 mg/dm2. Hence, rutin induced CS/PVA bioactive films have potential to be used for improving food quality and extending the shelf life of food.

Cucumis metuliferus Fruit Extract Loaded Acetate Cellulose Coatings for Antioxidant Active Packaging.

A new active coating was developed by using Cucumis metuliferus fruit extract as antioxidant additive with the aim of obtaining an easy way to functionalize low-density polyethylene (LDPE) films for food packaging applications. Thus, an extraction protocol was first optimized to determine the total phenolic compounds and the antioxidant activity of CM. The aqueous CM antioxidant extract was then incorporated into cellulose acetate (CA) film-forming solution in different concentrations (1, 3 and 5 wt.%) to be further coated in corona-treated LDPE to obtain LDPE/CA-CM bilayer systems. CA and CA-CM film-forming solutions were successfully coated onto the surface of LDPE, showing good adhesion in the final bilayer structure. The optical, microstructural, thermal, mechanical and oxygen barrier performance, as well as the antioxidant activity, were evaluated. The active coating casted onto the LDPE film did not affect the high transparency of LDPE and improved the oxygen barrier performance. The antioxidant effectiveness of bilayer packaging was confirmed by release studies of Cucumis metuliferus from the cellulose acetate layer to a fatty food simulant. Finally, the LDPE/CA-CM active materials were also tested for their application in minimally processed fruits, and they demonstrated their ability to reduce the oxidation process of fresh cut apples. Thus, the obtained results suggest that CA-CM-based coating can be used to easily introduce active functionality to typically used LDPE at industrial level and enhance its oxygen barrier, without affecting the high transparency, revealing their potential application in the active food packaging sector to extend the shelf-life of packaged food by prevention of lipid oxidation of fatty food or by prevention fruit browning.