UV Barrier Properties Research Articles

Poly (lactic acid)-based pH responsive membrane combined with chitosan and alizarin for food packaging

A poly (lactic acid) (PLA) -based functional partition composite membrane (PLA/CA) containing chitosan (CS) and alizarin (AL) was designed by solution casting method. The PLA/CA membrane contains the antibacterial zone of the edge part (PLA/CS) and the pH response detection zone of the central part (PLA/AL). At the same time, the environmentally friendly plasticizer tributyl citrate (TBC) was added to make the prepared PLA/CA composite membrane have good flexibility and high transparency. The results of FE-SEM and FTIR showed that CS and AL were uniformly dispersed in PLA matrix and had good compatibility with PLA. The antioxidant activities of PLA/CS and PLA/AL composite films were 43.3 % and 72.8 %, respectively. At the same time, the inhibitory rates of PLA/CS membrane against Escherichia coli and Staphylococcus aureus were as high as 87.91 % and 75.17 %, respectively. PLA/AL films exhibit excellent UV barrier properties. When the environmental pH (ammonia and acetic acid vapor) changed repeatedly, the PLA/AL membrane showed reversible color change of yellow under acidic condition and purple under alkaline condition. During the packaging and storage of chicken breast meat, the freshness of chicken breast meat can be detected by the color change of functional PLA/CA composite membrane.

Antimicrobial, antioxidant, and pH-sensitive polyvinyl alcohol/chitosan-based composite films with aronia extract, cellulose nanocrystals, and grapefruit seed extract

Aronia or black chokeberry (Aronia melanocarpa), cellulose nanocrystals (CNCs), and grapefruit seed extract (GSE) were used for the preparation of multifunctional polyvinyl alcohol/chitosan (PVA/CS) composite films with pH-sensitivity, antimicrobial, antioxidant, and UV-barrier properties. Aronia extract showed total phenolic content of 297 ± 0.5 μg GAE/mg aronia extract, potent antioxidant activity, and high color-response efficiency. Isolated CNCs showed a needle-like structure with a length of 470 nm and a width of 35 nm. The tensile strength of the PVA/CS composite film increased by 74% after the incorporation of CNCs, whereas the film flexibility was enhanced by 75% after adding GSE. The PVA/CS-A (aronia extract) composite film showed a significant color change at different pHs and potent antioxidant activity. At the same time, the PVA/CS-G (GSE) showed the highest antimicrobial activity against Escherichia coli (Gram-negative) and Listeria monocytogenes (Gram-positive) bacteria. The PVA/CS-CGA composite film, reinforced with CNCs/GSE/Aronia extract, showed the highest UV-barrier (95.5%), highest antioxidant activity (95%), potent antimicrobial activity, pH-sensitivity, lowest water vapor permeability (WVP), and desirable mechanical properties. The multifunctional properties of the produced composite films encourage their use as active and intelligent food packaging films to extend shelf life and monitor food quality.

Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films.

Poly(lactic acid) (PLA) represents one of the most widely used biodegradable polymers for food packaging applications. While this material provides many advantages, it is characterized by limited antioxidant and UV-barrier properties. Blending PLA with lignin is an attractive strategy to address these limitations. Lignin possesses antioxidant properties and absorbs UV-light and is a widely available low value byproduct of the paper and pulp industry. This study has explored the use of lignin nanoparticles to augment the properties of PLA-based films. A central challenge in the preparation of PLA–lignin nanoparticle blend films is to avoid nanoparticle aggregation, which could compromise optical properties as well as antioxidant activity, among others. To avoid nanoparticle aggregation in the PLA matrix, PLA-grafted lignin nanoparticles were prepared via organocatalyzed lactide ring-opening polymerization. In contrast to lignin and unmodified lignin nanoparticles, these PLA-grafted lignin nanoparticles could be uniformly dispersed in PLA for lignin contents up to 10 wt %. The addition of as little as the equivalent of 1 wt % of lignin of these nanoparticles effectively blocked transmission of 280 nm UV-light. At the same time, these blend films retained reasonable visible light transmittance. The optical properties of the PLA lignin blend films also benefited from the well-dispersed nature of the PLA-grafted nanoparticles, as evidenced by significantly higher visible light transmittance of blends of PLA and PLA-grafted nanoparticles, as compared to blends prepared from PLA with lignin or unmodified lignin nanoparticles. Finally, blending PLA with PLA-grafted lignin nanoparticles greatly augments the antioxidant activity of these films.

Formulation, Characterization and Optimization of β-Glucan and Pomegranate Juice Based Films for Its Potential in Diabetes.

The aim of this study was to develop films based on β–glucans in association with pomegranate juice for its potential in metabolic disorders such as diabetes due to plenty of bioactive compounds from the film composition. Initially, a Box-Behnken design was generated by varying the level of β–glucan content (0.5, 1, 1.5 g), sodium alginate (0.2, 0.4, 0.6 g) and pomegranate juice (10, 20, 30 mL) for development of films. Subsequently, glycerin was added as 25% of the total dry matter. The optimization of the films prepared by the solvent casting method was conducted based on the different responses such as: water vapor transmission rate (WVTR), water vapor permeability (WVP), thickness, density, moisture content, solubility, film opacity and color. The water activity profile and FT–IR analysis were performed in all tests. The model was used to determine the optimal experimental values considering that the optimal film will make a sustained contribution to diabetes. The optimal values of the film sample made of β–glucans, sodium alginate, pomegranate juice and glycerin make it befitting for packaging dry powdered pharmaceuticals. Finally, antimicrobial activity against Gram-negative and Gram-positive bacteria, UV barrier properties and microcrack and pore detections through SEM were also investigated for the optimal film sample.

Development of alginate-based edible coatings of optimized UV-barrier properties by response surface methodology for food packaging applications

Despite the outstanding characteristics of alginate, it suffers from bad UV-barrier, water barrier, and antimicrobial properties limiting its wide usage in food packaging. For this concern, Box-Behnken design (BBD) was applied to prepare an alginate-based edible coating of the best optimized UV-shielding properties upon the incorporation of both Aloe vera (AV) and zinc oxide nanoparticles (ZnO-NPs). The optimized minimum UV-transmittance was 4.96% when the optimized compositions of alginate (1.05 g), AV (2.95 g), and ZnO-NPs (4.93 wt%) were used. FTIR was used to verify the successful edible coating preparation while the wide-angle X-ray diffraction (XRD) was used to identify the interactions between the film's components. The incorporation of both AV and ZnO-NPs significantly improved alginate's thermal, water vapor permeability (WVP), mechanical and antimicrobial properties. In addition, the films incorporated with both AV and ZnO-NPs exhibited excellent UV-barrier properties compared with neat alginate. The optimized alginate film incorporated with both ZnO-NPs and AV significantly extended the shelf-life of tomato fruits up to 16 days without any defects. Due to the outstanding physical, UV-shielding, and antimicrobial properties of the optimized alginate/AV/ZnO-NPs film, it could be used potentially in food packaging industries.

Exploration of multifunctional properties of garlic skin derived cellulose nanocrystals and extracts incorporated chitosan biocomposite films for active packaging application

For many years, garlic has been used as a condiment in food and traditional medicine. However, the garlic skin, which accounts for 25% of the garlic bulk, is considered agricultural waste. In this study, cellulose nanocrystals (CNCs) and garlic extract (GE) from garlic skin were isolated and used as fillers to manufacture biocomposite films. The films were characterized in terms of UV barrier, thermal, mechanical, biodegradability, and antimicrobial activity. The chitosan-containing films and CNCs have significantly improved the films' tensile strength, Young's modulus, and elongation but decreased the film transparency compared to chitosan films. The combination of the CNCs and GE, on the other hand, slightly reduced the mechanical properties. The addition of CNCs slightly decreased the film transparency, while the addition of GE significantly improved the UV barrier properties. Thermal studies revealed that the incorporation of CNC and GE had minimal effect on the thermal stability of the chitosan films. The degradability rate of the chitosan composite films was found to be higher than that of the neat chitosan films. The antimicrobial properties of films were studied against Escherichia coli, Streptomyces griseorubens, Streptomyces alboviridis, and Staphylococcus aureus, observing that their growth was considerably inhibited by the addition of GE in composite films. Films incorporating both CNCs and GE from garlic skin hold more promise for active food packaging applications due to a combination of enhanced physical characteristics and antibacterial activity.

Boosting physical-mechanical properties of adipic acid/chitosan films by DMTMM cross-linking

In this paper we present a novel strategy to easily prepare biodegradable chitosan derived films as new packaging systems. Combination of chitosan, adipic acid and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM) allowed to obtain high-performing cross-linked films. Biobased glycerol was employed as plasticizer. An in-depth study was performed on ten different samples in order to evaluate the role of DMTMM as cross-linking agent. Experimental data showed that 15 wt% of DMTMM enhanced moisture content and moisture uptake (10.42% and 11.11%), water vapor permeability (0.13 10−7 g m−1 h−1 Pa−1) and good UV barrier properties. Additionally, 30 wt% of DMTMM significantly increased the tensile strength of films up to 83 MPa and elongation at break values reached 39.7%. Thermogravimetric, IR, XRD and SEM analysis confirmed that physical-mechanical properties of the obtained films were considerably improved, due to cross-linking by DMTMM, demonstrating promising properties for packaging applications.

Alginate-based multifunctional films incorporated with sulfur quantum dots for active packaging applications

Sulfur quantum dots (SQDs) were fabricated using a facile hydrothermal method and used for the preparation of functional food packaging film and compared the properties with other sulfur-based fillers like elemental sulfur (ES) and sulfur nanoparticles (SNP). The SQDs have an average size of 5.3 nm and were very stable in aqueous suspension. Unlike other sulfur-based fillers, the SQD showed high antioxidant, antibacterial and antifungal activity, but no cytotoxicity was found for L929 mouse fibroblasts even after long-term exposure of 48 h. When sulfur-based fillers were added to the alginate film, SQD was more evenly dispersed in the polymer matrix than SNP and ES. The addition of SQD to the alginate film increased the film's UV barrier property by 82% and tensile strength by 18%. Also, the addition of SQDs to the films did not affect the stiffness (elastic modulus, EM) and water vapor barrier permeability (WVP) of the films. In addition, SQD-added films exhibited excellent antioxidant and strong antibacterial activity against bacterial (E. coli and L. monocytogenes) and fungal (A. niger and P. chrysogenum) food pathogens. When the film was applied as a bread packaging test, the SQD-added film prevented mold growth for 14 days, unlike the ES and SNP-added films.

Fabrication of Antioxidant and Antimicrobial Pullulan/Gelatin Films Integrated with Grape Seed Extract and Sulfur Nanoparticles.

Biopolymer-based functional blend films were prepared using pullulan and gelatin with functional fillers of sulfur nanoparticles (SNPs) and grape seed extract (GSE). A mixture of pullulan/gelatin (1:1) produced a compatible but slightly translucent free-standing film. SNPs capped with enoki mushroom extract and GSE were added as functional fillers to improve the properties (physical and functional) of the pullulan/gelatin-based film. The addition of SNP and GSE significantly (p < 0.05) boosted the UV-light barrier, water vapor barrier, and oxygen barrier properties of the pullulan/gelatin films. The mechanical performance of the pullulan/gelatin-based films was slightly decreased (∼10%), whereas the addition of fillers did not significantly affect the hydrophobicity and thermal stability. The addition of SNP provided the antimicrobial function against foodborne pathogenic bacteria, L. monocytogenes and E. coli, while GSE provided a powerful antioxidant activity to the pullulan/gelatin-based film. Therefore, pullulan/gelatin-based composite films with better UV, water vapor, and oxygen barrier properties and enhanced antioxidant and antibacterial properties are expected to have high utility in active food packaging applications.

Improved Hydrophobic, UV Barrier and Antibacterial Properties of Multifunctional PVA Nanocomposite Films Reinforced with Modified Lignin Contained Cellulose Nanofibers.

In this study, we reported PVA nanocomposite films enhanced by polyethyleneimine (PEI)-lignin contained cellulose nanofibers (LCNFs) via the solvent casting method. An easy and available method was preformed to prepare LCNFs using a supermasscolloider from unbleached bamboo waste after a mild alkaline pretreatment. The results demonstrate that LCNF–PEI can greatly improve mechanical, hydrophobic, anti-UV shielding and antibacterial properties of the composite films. The tensile strength of LPP1 film was improved to 54.56 MPa, which was higher than 39.37 MPa of PVA film. The water contact angle of films increased from 35° to 104° with an increase in LCNF content from 0 to 6 wt%. Meanwhile, the nanocomposite film demonstrated the effect of full shielding against ultraviolet light when the amount of LCNF–PEI reached 6 wt%. The addition of LCNF–PEI endowed excellent antibacterial activity (against S. aureus and E. coli), which indicated potential applications in the packaging field.

In situ one‐step fabrication of layered double hydroxide deposited on cellulose: Effect of modified cellulose on physical properties of polyurethane composites

AbstractThe article reports the fabrication of cellulose‐layered double hydroxide (LDH) obtained by urea hydrolysis method. A wide characterization was carried out to assess the morphological, spectroscopic and barrier properties of LDH modified cellulose. The cellulose‐LDH was then used as hybrid reinforcement in polyurethane (PU) composites. A slight improvement in thermal stability of PU was achieved and a better hydrophilicity was obtained, due to the intrinsic polarity of LDH. Elastic modulus of PU composites increased up to 48 MPa for a filler loading of 10% wt. Finally, UV barrier properties were studied in the range 280–700 nm. The produced composite showed a noticeable decrease in light transmission as the reinforcement content increase, displaying high light‐blocking properties with a quasi‐total resistance to transmission in UV range.

Gelatin-based packaging material incorporated with potato skins carbon dots as functional filler

Carbon dots (CD) were developed via hydrothermal synthesis using potato peel as functional fillers for food packaging films. The CD showed strong antioxidant and antimicrobial activity with low cytotoxicity as more than 80% of mouse fibroblast L929 cells survived even when exposed to 500 μg/mL for 72 h. The CD was used as a functional filler for preparing a gelatin-based functional film, and it was uniformly dispersed in biopolymer, indicating a compatible packaging film. The FTIR result showed no change in the chemical structure, but an H-bond was apparent between the CD and gelatin. The addition of CD produced a highly transparent film with significant improvement in the water vapor permeability (by 28%) and hydrophobicity (by 9% and 13%) properties of the gelatin film without much changing of the mechanical properties. The CD-added gelatin films indicated UV-barrier property and strong antioxidant activity. Moreover, the antibacterial efficacy increased significantly. Therefore, the CD-added gelatin films have great potential as a value-added, low-cost, safe, and functional nanofiller for the preparation of packaging applications.

Alginate Biofunctional Films Modified with Melanin from Watermelon Seeds and Zinc Oxide/Silver Nanoparticles.

Bioactive films find more and more applications in various industries, including packaging and biomedicine. This work describes the preparation, characterization and physicochemical, antioxidant and antimicrobial properties of alginate films modified with melanin from watermelon (Citrullus lanatus) seeds at concentrations of 0.10%, 0.25% and 0.50% w/w and with silver and zinc oxide nanoparticles (10 mM film casting solutions for both metal nanoparticles). Melanin served as the active ingredient of the film and as a nanoparticle stabilizer. The additives affected the color, antioxidant (~90% ABTS and DPPH radicals scavenging for all melanin modified films) and antimicrobial activity (up to 4 mm grow inhibition zones of E. coli and S. aureus for both zinc oxide and silver nanoparticles), mechanical (silver nanoparticles addition effected two-fold higher tensile strength), thermal and barrier properties for water and UV-vis radiation. The addition of ZnONP resulted in improved UV barrier properties while maintaining good visible light transmittance, whereas AgNP resulted in almost complete UV barrier and reduced visible light transmittance of the obtained films. What is more, the obtained films did not have an adverse effect on cell viability in cytotoxicity screening. These films may have potential applications in food packaging or biomedical applications.

Physiochemical, antioxidant, and food simulant release properties of collagen‐carboxymethyl cellulose films enriched with Berberis lyceum root extract for biodegradable active food packaging

The fish processing by-products are generally predicted as low-cost resources and used as feed for aquaculture and fertilizers for agriculture. This study aimed to extract collagen type-I from fish-discarded skin and their application in the fabrication of active food packaging films. Carboxymethyl cellulose (CMC) was used in collagen films as a cross linker and Berberis lyceum root extract (BLRE) as an antioxidant agent. Films prepared with BLRE presented outstanding features, such as high biodegradability, low transparency, and high UV-Vis barrier properties. In addition, BLRE-loaded films showed excellent antioxidant activities. Further, the exposure of the film to different food simulants showed higher antioxidant release in acidic, and alcoholic food simulants as compared to fatty food simulants. Additionally, these films were also used to wrap mushrooms in order to increase their shelf life. Hence, the present study encourages collagen extraction from fish waste and its use as biodegradable food packaging materials. Novelty impact statement Fish skin is an aquaculture waste but still contains a high amount of collagen type-I, which can be used in combination with CMC to fabricate active food packaging films. These films incorporated with BLRE showed excellent antioxidant activities. Moreover, these films offered a high UV barrier and biodegradable properties. The film’s biodegradability in soil within 10 days increases their application as environmentally friendly materials. Further, these films can effectively prolong the shelf life of mushrooms. Therefore, the bioactive collagen-CMC film provides an effective alternative to synthetic film to maintain the quality and prolong the shelf-life of oily and dry food products.

Polyvinyl alcohol/cellulose nanocrystals/alkyl ketene dimer nanocomposite as a novel biodegradable food packing material

Polyvinyl alcohol (PVA) is used in many applications because of its excellent physicochemical properties, non-toxicity, and biodegradability. However, its relatively low water resistance, poor water vapor/ultraviolet (UV) barrier properties, and poor mechanical properties compared with conventional polymers limit its applications in food packaging. In this study, cellulose nanocrystals (CNCs) and alkyl ketene dimer (AKD) were used to overcome these issues. The mechanical properties, water resistance, and barrier properties of the developed PVA/CNC/AKD films were significantly improved relative to those of a neat PVA film. The mechanical strength of a PVA/CNC/AKD 15% film (15 wt% AKD in a PVA/CNC matrix of 5 wt% CNCs) was 64.6% and 37% higher than those of PVA and PVA/CNC films, respectively. The water vapor transmission rate, water absorption, and solubility of PVA/CNC/AKD 15% were 41.2%, 61.1%, and 92.9%, respectively (lower than those of the neat PVA film). In addition, the UV barrier properties and soil degradation of the PVA/CNC/AKD films were significantly improved.

Effect of different cation in situ cross-linking on the properties of pectin-thymol active film

In this work, the effect of in situ cross-linking of different cations on the properties of pectin-thymol active films was investigated. Specifically, pectin-thymol composite films (P-T) were developed by solution casting method, and then P-T/Ca, P-T/Fe, and P-T/Cu films with enhanced properties were developed by in situ cation cross-linking in 50% (v/v) ethanol-water solution containing Ca2+, Fe3+, and Cu2+, respectively. The thickness, color, optical properties, water sensitivity, water vapor permeability, mechanical properties, antimicrobial properties and thymol release properties of films were investigated. The interactions and specific micromorphology of films were also analyzed using FTIR and scanning electron microscope. The results showed that Fe3+ and Cu2+ could be uniformly distributed on the film surface and diffused into the interior by external in situ cross-linking. And the water resistance of the composite pectin films was significantly enhanced by the in situ cross-linking with different cations. The P-T/Fe films exhibited excellent UV-barrier properties. The mechanical properties and water vapor barrier properties of cation cross-linked P-T films were also improved. In addition, this work indicated that “egg-box” model formed between the cation and pectin molecule has a slow release effect on thymol in pectin films, which provides a new idea for the controlled release of active substances in pectin films.

Assessment of physical and thermal behaviour of chitosan-based biocomposites reinforced with leaf and stem extract of Tectona grandis

Chitosan (Ch) has been incorporated with Tectona grandis leaf extract and stem extract at different compositions (5%, 10% and 15% v/v) to study the physicochemical properties of the biocomposites. The thin-film composites were prepared by the solution casting method to investigate the removal of chromium (VI) from water at varied pH conditions. The results showed that incorporation of the plant extracts improved the mechanical and UV barrier properties of the TFCs. Thermo-gravimetric analysis (TGA) showed that the degradation temperature of the films containing the extracts improved only slightly in comparison to the control film. Adsorption studies showed that for maximum Cr (VI) removal, Ch-L5 and Ch-L10 films were efficient. These eco-friendly prepared films are cost-effective and can also be a suitable material for food packaging.

Mass Transfer and Optical Properties of Active PET/PP Food-Grade Films Impregnated with Olive Leaf Extract

A supercritical solvent impregnation (SSI) technique was employed to incorporate, by batch- and semicontinuous-modes, bioactive olive leaf extract (OLE) into a food-grade multilayer polyethylene terephthalate/polypropylene (PET/PP) film for active food packaging applications. The inclusion of OLE in the polymer surfaces significantly modified the colour properties of the film. A correlation of 87.06% between the CIELAB colour parameters and the amount of the OLE impregnated in the film was obtained which suggests that colour determination can be used as a rapid, non-destructive technique to estimate the OLE loading in the impregnated matrices. The UV barrier and water permeability properties of the films were not significantly modified by the incorporation of OLE. The migration of OLE into a 50% (v/v) ethanol food simulant demonstrated faster release of OLE from the PP surface than from the PET surface which may be due to the different interactions between OLE and each polymer.

Sulfur Quantum Dots as Fillers in Gelatin/Agar-Based Functional Food Packaging Films

The present work is the first attempt to study the applicability of sulfur quantum dots (SQDs) as functional fillers for food packaging biopolymer films. SQDs were prepared via hydrothermal synthesis using sublimated sulfur powder. The SQDs were 8.7 nm in size and consisted of an elemental sulfur core stabilized by PEG-400 confirmed by TEM, FTIR, and XPS characterization. The SQDs exhibited a high surface charge of −13.9 mV, indicating good dispersion in aqueous suspensions. In addition, the SQDs showed high antioxidant and antimicrobial activities with almost negligible toxicity toward L929 cells even at prolonged exposure of 72 h. The addition of SQDs to the gelatin/agar blend films increased the UV-barrier property without compromising color and transparency. The composite film showed excellent antioxidant activity, a moderate bactericidal effect on Listeria monocytogenes, and an inhibitory effect on Escherichia coli. The SQDs are likely to be value-added, low-cost, safe, and multifunctional nanofillers for preparing functional films in active packaging applications.

Preparation and physicochemical assessment of bioactive films based on chitosan and starchy powder of white turmeric rhizomes (Curcuma Zedoaria) for green packaging applications

In the current study, the bioactive films of chitosan/white turmeric (CH/WT) were prepared by employing solvent casting technique and analyzed their physicochemical and biological properties for active packaging applications. The successful inclusion of white turmeric into the chitosan matrix is confirmed by Fourier Transform Infrared Spectroscopy. Due to the presence of hydrogen bonding interaction, the active films exhibited good tensile properties, smooth surface morphology, miscibility, water resistance and UV barrier properties. The incorporation of white turmeric reduced the water vapour transmission rate and oxygen permeability (p < 0.05) in contrast with pristine film. The prepared blend films revealed soil degradation rate more than 60% within 15 days. Furthermore, the blend films exhibited lesser water solubility, moisture content and swelling index after addition of white turmeric to chitosan (p < 0.05). The prepared films revealed extensive antimicrobial activity against gram positive and gram negative bacteria. The antioxidant activity and total phenolic content were improved upon the incorporation of white turmeric. Moreover, the oil absorption rate of the blend films was decreased by 46% in comparison with pristine film. Overall, white turmeric incorporated chitosan films were employed as a green packaging material to extend the shelf life of the foodstuff.