Plasticizer concentration effect on films and coatings based on poly(vinyl alcohol) and cationic starch blends

Films based on poly(vinyl alcohol) (PVA) and cationic starch (CS) were combined with different percentages of sorbitol (S; 15.0, 22.5, and 30.0% w v-1) to assess the effect of plasticizer on the films. Spectroscopic analyses confirmed the interaction between them. However, micrographs indicated the formation of sorbitol crystals on the surface of the films, especially at higher sorbitol concentrations. The blends presented low water vapor transmission rate values, reaching (7.703 ± 0.000) g h-1 m-2 (PVA75CS25S15), and low solubility values for the films containing higher CS amounts. The lack of statistical differences in most parameters suggests that no significant gain comes from increasing the amount of sorbitol at percentages higher than 15%. As a coating, the blend PVA75CS25S15 successfully decreased the loss of moisture content in acerolas by 1.15 times (compared to the control), confirming the suitability of this matrix as a fruit coating.

Optimization and characterization of biodegradable films from chicken gelatin crosslinked with oxidized phenolic compounds

Chicken gelatin derived from poultry by-product was combined with caffeic acid (CA), rutin (RUT) and glycerol (GLY) to obtain biodegradable films. Optimum cross-linking conditions were investigated using Response Surface Methodology (RSM). The results showed that cross-linking led to lower L* value and higher b*, and the higher opacity values in the films. Water solubility (WS) decreased up to 50% after the incorporation of 1.25% CA compared to the commercial gelatin (cattle and pig based) films. Crosslinking improved the thermal stability and the tensile strength (TS) of films. Optimized cross-linking combination was determined as 0.96-1.56% CA, 0-1.25% RUT, and 29.5-30.5% GLY. Overall, this study demonstrated that crosslinking by CA and RUT can be used to improve the physical and barrier properties of gelatin films having excellent potential for the development of biodegradable films for packaging uses. These films may also result in an improvement and added value in poultry by-products.

Sustainable food packaging: Harnessing biowaste of Terminalia catappa L. for chitosan-based biodegradable active films for shrimp storage

Shrimp, a globally consumed perishable food, faces rapid deterioration during storage and marketing, causing nutritional and economic losses. With a rising environmental consciousness regarding conventional plastic packaging, consumers seek sustainable options. Utilizing natural waste resources for packaging films strengthens the food industry. In this context, we aim to create chitosan-based active films by incorporating Terminalia catappa L. leaves extract (TCE) to enhance barrier properties and extend shrimp shelf life under refrigeration. Incorporation of TCE improves mechanical, microstructural, UV, and moisture barrier properties of the chitosan film due to cross-linking interactions, resulting in robust, foldable packaging film. Active TCE film exhibits high antioxidant property due to polyphenols. These films also exhibited low wettability and showed hydrophobicity than neat CH films which is essential for meat packaging. These biodegradable films offer an eco-friendly end-of-life option when buried in soil. TCE-loaded films effectively control spoilage organisms, prevent biochemical spoilage, and maintain shrimp freshness compared to neat CH films during refrigerated condition. The active TCE film retains sensory attributes better than neat chitosan, aligning with consumer preference. The developed edible and active film from waste sources might offer sustainable, alternative packaging material with a lower carbon footprint than petroleum-based sources.

Polymeric films of corn starch enhance the lethal effects of thymol and carvacrol terpenes upon Rhipicephalus microplus ticks

The tick Rhipicephalus microplus is a parasite of great importance in cattle breeding. It is responsible for huge economic losses. The application of synthetic acaricides is used as a form of control. However, resistant strains have been selected over the years, making it necessary to search for new alternative formulations. The present study aimed to formulate biodegradable films impregnated with the terpenes carvacrol and thymol and evaluate their efficacy on larvae and adults of R. microplus through in vitro tests. The following formulations were prepared: Film 1 (starch based); Film 2 (based on starch and glycerol); Film 1 + Carvarcol or Thymol; Film 2 + Carvarcol or Thymol. Terpenes had a final concentration of 5.0 mg/mL. To evaluate the formulations on larvae, the immersion test was performed by dividing into six groups according to the concentration of terpenes: 5.0, 2.5, 1.25, 0.625, 0.313, 0.156 mg/mL and the control groups: 1% ethanol solution; 10% ethanol solution; Film 1; and Film 2. For the evaluations on adult ticks, ten experimental groups (n = 10) were used: 1) Carvacrol; 2) Film 1 + Carvacrol; 3) Film 2 + Carvacrol; 4) Thymol; 5) Film 1 + Thymol; 6) Film 2 + Thymol; 7) Distilled water; 8) 10% ethanol solution; 9) Film 1; and 10) Film 2. In experimental groups 1-6, carvacrol and thymol (free or incorporated in two different biodegradable film formulations) were evaluated at the same concentration (5.0 mg/mL). Each group of ticks was immersed in their respective solutions for five minutes. The results of the tests on larvae showed that the Film 1 + thymol and Film 2 + carvacrol formulations had the lowest lethal concentrations (0.076 and 0.255 mg/mL, respectively), values up to 9.0-fold lower than the monoterpenes tested outside the formulation. Carvacrol and thymol at the concentrations tested were effective in controlling engorged females with a percentage of 32.2% and 63.8%, respectively. When incorporated into biodegradable film formulations, these monoterpenes showed much greater efficacy. Film 1 + carvacrol and Film 2 + carvacrol with control percentages of 71.6% and 97.2%, respectively, while the formulations Film 1 + thymol and Film 2 + thymol showed values of 96.9% and 100.0%. The tick control activity of the biopolymer formulations with thymol and carvacrol was demonstrated through the high mortality rates of larvae and engorged females of the tick R. microplus. Therefore, the results obtained indicate that these formulations have great potential for tick control mainly because of the percentage of control up to 100% in engorged females in in vitro tests.

Sodium alginate films incorporated with Lepidium sativum (Garden cress) extract as a novel method to enhancement the oxidative stability of edible oil

This study addresses the growing interest in bio-based active food packaging by infusing Lepidium sativum (Garden cress) seeds extract (GRCE) into sodium alginate (SALG) films at varying concentrations (1, 3, and 5 %). The GRCE extract revealed six phenolic compounds, with gallic and chlorogenic acids being prominent, showcasing substantial total phenolic content (TPC) of 139.36 μg GAE/mg and total flavonoid content (TFC) of 26.46 μg RE/mg. The integration into SALG films significantly increased TPC, reaching 30.73 mg GAE/g in the film with 5 % GRCE. This enhancement extended to DPPH and ABTS activities, with notable rises to 66.47 and 70.12 %, respectively. Physical properties, including tensile strength, thickness, solubility, and moisture content, were positively affected. A reduction in water vapor permeability (WVP) was reported in the film enriched with 5 % GRCE (1.389 × 10-10 g H2O/m s p.a.). FT-IR analysis revealed bands indicating GRCE's physical interaction with the SALG matrix, with thermal stability of the films decreasing upon GRCE integration. SALG/GRCE5 effectively lowered the peroxide value (PV) of sunflower oil after four weeks at 50 °C compared to the control, with direct film-oil contact enhancing this reduction. Similar trends were observed in the K232 and K270 values.

Fabrication of flexible chitosan film reinforced with pulping by-product lignosulfonates for cherry-tomato preservation

The massive production of food waste and plastic pollution necessitates innovative solutions. This study reports the first fabrication of a flexible chitosan (CH) film reinforced with lignosulfonate (LS) derived from pulping byproduct as a sustainable alternative to synthetic food packaging. The CH/LS composite film was prepared by a simple casting method with varying LS contents of 1 % and 2 %. Compared to CH film, the addition of 2 % LS increased the tensile strength by over 4 times and decreased water vapor permeability by 11 %. Moreover, the CH/LS film exhibited excellent UV-shielding properties. This novel use of LS to reinforce CH film presents an eco-friendly active packaging material. When used to package cherry tomatoes for 2 weeks, the CH/LS film effectively maintained fruit freshness and hardness while minimizing weight loss. This work provides new scientific evidence on the optimized preparation and application of CH/LS composite films from renewable resources for food preservation.

Starch/poly (butylene adipate-co-terephthalate) blown films contained the quaternary ammonium salts with different N-alkyl chain lengths as antimicrobials

Antimicrobial biodegradable packaging is in high demand as a one-two punch against microbiological and plastic hazards. Two quaternary ammonium salts (QAS) with different N-alkyl chain lengths were used for starch/poly (butylene adipate-co-terephthalate) (PBAT) blown antimicrobial films. Dioctadecyl dimethyl ammonium chloride (D1821) contributed to a homogeneous film morphology at 5% w/w level, while micro-pores occurred with didodecyl dimethyl ammonium chloride (D1221). Increasing QAS content weakened hydrogen bonding interactions. D1821 promoted the formation of intercalated structure of nano-clays, and improved the strength, thermal stability, barrier, and surface hydrophobicity of the films. Conversely, adding D1221 decreased the mechanical properties, and significantly enhanced the surface hydrophilicity. The films with 3% and 5% w/w D1221 obviously inhibited the growth of both Staphylococcus aureus and Escherichia coli, while those with D1821 cannot show clear zone against the Gram-negative. 5% w/w D1221-loaded film delayed the growth of microorganisms in beef, of which the total viable count was 5.75 lg CFU/g after 21-day chilling storage. Findings supported that QAS had the potential for manufacturing starch/PBAT antimicrobial packaging, but the release kinetics and cytotoxicity still need to be systematically explored before application.

Berry wax improves the physico-mechanical, thermal, water barrier properties and biodegradable potential of chitosan food packaging film

Chitosan (CT) is extensively applied in developing food packaging films due to its non-toxic, biodegradable, and good film-forming properties. But CT-based single polymer film has issues with poor physico-mechanical, thermal, and light barrier properties. Therefore, this study aimed to incorporate natural berry wax (BYW) at various concentrations (5 %, 10 %, 15 %, 20 %, and 25 %, wt%) into CT to improve the quality characteristics of CT film. The microstructure of the film matrix was effectively proven to be compatible with BYW through the utilization of SEM, XRD, and FTIR spectroscopy. The results demonstrated that the quality parameters of CT/BYW composite film were significantly affected by the increasing concentration of BYW. The integration of BYW with a concentration of 5 % to 20 % to CT substantially improved the film characteristics by reducing moisture content, swelling power, solubility, and water vapor permeability, increasing the film's opacity, thermal stability, and tensile strength as well as enhancing the biodegradable potential. Furthermore, CT/BYW films showed higher thermal stability and UV and visible light resistance compared to pure CT film. Taken together, the CT film with 20 % berry wax showed the best film characteristics and biodegradable potential, which could be promising for enhancing the shelf-life of various food products.

A biodegradable oxidized starch/carboxymethyl chitosan film coated with pesticide-loaded ZIF-8 for tomato fusarium wilt control

Film mulching is one of the most important methods to control soil-borne diseases. However, the traditional mulch may cause microplastic pollution and soil ecological damage. Herein, a biodegradable film was developed using oxidized starch and carboxymethyl chitosan and incorporated ZIF-8 carrying fludioxonil to sustainably control soil-borne disease. The microstructure, mechanical properties, optical properties, and water barrier properties of the composite films (Flu@ZIF-8-OS/CMCS) were investigated. The results show that Flu@ZIF-8-OS/CMCS had a smooth and uniform surface and excellent light transmittance. The excellent mechanical properties of the films were verified by tensile strength, elongation at break and Young's modulus. Higher contact angle and lower water vapor permeability indicate water retention capacity of the soil was improved through using Flu@ZIF-8-OS/CMCS. Furthermore, the release properties, biological activity, degradability and safety to soil organisms of Flu@ZIF-8-OS/CMCS was determined. The addition of ZIF-8 significantly improved the film's ability to retard the release of Flu, while the Flu@ZIF-8-OS/CMCS has good soil degradability. In vitro antifungal assays and pot experiments demonstrated excellent inhibitory activity against Fusarium oxysporum f. sp. Lycopersici. Flu@ZIF-8-OS/CMCS caused only 13.33 % mortality of earthworms within 7 d. This research provides a new approach to reducing microplastic pollution and effectively managing soil-borne diseases.

Enhanced mechanical strength of vortex fluidic mediated biomass-based biodegradable films composed from agar, alginate and kombucha cellulose hydrolysates

Biodegradable, biomass derived kombucha cellulose films with increased mechanical strength from 9.98 MPa to 18.18 MPa were prepared by vortex fluidic device (VFD) processing. VFD processing not only reduced the particle size of kombucha cellulose from approximate 2 μm to 1 μm, but also reshaped its structure from irregular to round. The increased mechanical strength of these polysaccharide-derived films is the result of intensive micromixing and high shear stress of a liquid thin film in a VFD. This arises from the incorporation at the micro-structural level of uniform, unidirectional strings of kombucha cellulose hydrolysates, which resulted from the topological fluid flow in the VFD. The biodegradability of the VFD generated polymer films was not compromised relative to traditionally generated films. Both films were biodegraded within 5 days.

Study of alkali-soluble curdlan/bacterial cellulose/cinnamon essential oil blend films with enhanced mechanical properties

In response to the growing demand for biodegraded film with high mechanical properties for complex preservation application scenarios, we developed a curdlan (CD) blended films with exceptional mechanical strength through an alkali dissolution method. Notably, the alkali-soluble CD film exhibited five-fold increase in tensile strength (TS) when compared to its water-soluble counterpart. Furthermore, the inclusion of 2 % bacterial cellulose (BC) resulted in a significant 41.1 % augmentation of the film's TS. Thermal stability improvements were observed through differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) results provided insights into alterations in film crystallinity and intermolecular interactions. Specifically, the incorporation of 10 % CEO led to an additional improvement in TS. Our experimental investigations involving the packaging of chilled fresh meat with these blended films unveiled their capacity to effectively inhibit microorganism growth, maintain meat color stability, delay protein decomposition and fat oxidation, and extend the storage time up to 9 days. Our study offers a promising solution for food packaging, emphasizing the development of a high-strength degradable CD/BC/CEO blended film, which holds potential for extending the shelf life of food products.

Novel edible films fabricated with HG-type pectin extracted from different types of hybrid citrus peels: Effects of pectin composition on film properties

This study investigated the valorization of novel HG-type hybrid citrus pectins derived from three cultivars: Setoka (ST), Kanpei (KP), and Shiranui (SH), and their application as packaging materials. The physicochemical properties of these pectins and their corresponding films were evaluated and compared to commercial citrus pectin. Significant variations were observed in pectin yield (18.15-24.12 %) and other physicochemical characteristics, such as degree of esterification (DE), degree of methoxylation (DM), and monosaccharide composition, among the different cultivars. All hybrid citrus pectins were classified as high-methoxy pectin types (66.67-72.89 %) with typical structural configurations like commercial citrus pectin. However, hybrid citrus pectin films exhibited superior physical properties, including higher mechanical strength, flexibility, and lower water solubility than commercial citrus pectin film, while maintaining similar transparency and moisture content. Additionally, the films displayed smooth and uniform surface morphology, confirming their excellent film-forming properties. Correlation analysis revealed that DE positively influenced mechanical properties (r = 1.0). Furthermore, the monosaccharide composition of pectins showed strong relationships (r = 0.8-1.0) with the film's mechanical and barrier properties. These findings highlight the potential of hybrid citrus pectin as potential packaging material, and the knowledge of the structure-function relationship obtained in this study could be useful for the tailored modification of citrus pectin-based packages.

Development of sodium alginate-pectin biodegradable active food packaging film containing cinnamic acid

Plastics are still the most popular food packaging material, and many of them end up in the environment for a long period. Besides, due to packaging material's inability to inhibit microbial growth, beef often contains microorganisms that affect its aroma, colour, and texture. Cinnamic acid is categorized as generally recognised as safe and is permitted for use in food, however, the development of biodegradable food packaging film with cinnamic acid has never been conducted before. Thus, this present study was aimed to develop a biodegradable active packaging material for fresh beef using sodium alginate and pectin. The film was successfully developed with solution casting method. The films' thickness, colour, moisture level, dissolution, water vapour permeability, bending strength, and elongation at break were comparable to those of polyethylene plastic film in terms of these attributes. The developed film also showed the degradability in soil of 43.26% in a duration of 15 days. Fourier Transform Infrared (FTIR) spectra showed that cinnamic acid was successfully incorporated with the film. The developed film showed significant inhibitory activity on all test foodborne bacteria. On Hohenstein Challenge Test, a 51.28-70.45% reduction on bacterial growth was also observed. The antibacterial efficacy of the established film by using fresh beef as food model. The meats wrapped with the film showed significant reduction in bacterial load throughout the experimental period by 84.09%. The colour of the beef also showed significant different between control film and edible film during 5 days test. Beef with control film turned into dark brownish and beef with cinnamic acid turn into light brownish. In conclusion, sodium alginate and pectin film with cinnamic acid showed good biodegradability and antibacterial activity. Further studies can be conducted to investigate the scalability and commercial viability of this environmental-friendly food packaging materials.

Development and characterization of a novel sodium alginate based active film supplemented with Lactiplantibacillus plantarum postbiotic

In this study, sodium alginate based biodegradable films were prepared by the supplementation with postbiotics of Lactiplantibacillus plantarum subsp. plantarum (L. plantarum) W2 strain and the effect of probiotics (probiotic-SA film) and postbiotics (postbiotic-SA film) incorporation on physical, mechanical (tensile strength and elongation at break), barrier (oxygen and water vapor permeability), thermal and antimicrobial properties of the films were investigated. The pH, titratable acidity and brix of the postbiotic was 4.02, 1.24 % and 8.37, respectively while gallic acid, protocatechuic acid, myricetin and catechin were the major phenolic compounds. Mechanical and barrier properties of the alginate-based films were improved by probiotic or postbiotic supplementation while postbiotic showed a more pronounced (P < 0.05) effect. Thermal analysis showed that postbiotics supplementation increased thermal stability of the films. In FTIR spectra, the absorption peaks at 2341 and 2317 cm^-1 for probiotic-SA and postbiotic-SA edible films confirmed the incorporation of probiotics/postbiotics of L. plantarum W2 strain. Postbiotic supplemented films showed strong antibacterial activity against gram-positive (L. monocytogenes, S. aureus and B. cereus) and one gram-negative bacterial strain (E. coli O157:H7) while probiotic incorporation did not add an antibacterial effect to the films. SEM images revealed that the supplementation of postbiotics provided a rougher and rigid film surface. Overall, this paper brought a new perspective for development of novel active biodegradable films by incorporation of postbiotics with improved performance.

Biodegradable antifungal films from nanocellulose-gellan gum incorporated with Anethum graveolens essential oil for bread packaging

Biodegradable material incorporated with antifungal essential oil has become an alternative food preservation approach to reduce plastic waste. Essential oils of Amomum testaceum, Anethum graveolens, Piper longum, Kaempferia galanga, and Zanthoxylum limonella were tested for their antifungal activity against Aspergillus niger. A. graveolens essential oil demonstrated the highest inhibition zone diameter of 43.51 mm against A. niger after seven days comparing to those obtained from other essential oils ranging from 10.02 mm to 26.13 mm. The volatile compounds of A. graveolens essential oil were identified with major compounds such as carvone, trans-dihydrocarvone, limonene, and α-acorenol. The pineapple nanocellulose-gellan gum (PNC-GG) films incorporated with A. graveolens oil were formulated and tested for its physical and chemical properties. Addition of A. graveolens essential oil in PNC-GG films improved mechanical strength and decreased flexibility while solubility, water vapour permeability, and thermal stability slightly changed. PNC-GG films incorporated with A. graveolens essential oil were also tested as bread packaging inhibiting A. niger. The results indicated that no visible mycelial growth of A. niger was detected during 3-week storage. Therefore, the PNC-GG films incorporated with A. graveolens essential oil were recommended as biodegradable packaging material against A. niger in bread also extending its shelf life.

Property improvement of a thermoplastic starch/poly(butylene adipate-co-terephthalate) blown film by the addition of sodium nitrite

Recently, global awareness of the adverse environmental impacts of single-use plastics has risen due to their nonbiodegradability and likelihood of ending up in the ocean. Thermoplastic starch (TPS) is an alternative material employed for manufacturing single-use products because of its high biodegradability, nontoxicity, and low cost. However, TPS is moisture sensitive and has poor mechanical properties and processability. Blending TPS with biodegradable polyesters, including poly(butylene adipate-co-terephthalate) (PBAT), can expand its practical applications. This research aims to improve the performance of TPS/PBAT blends by adding sodium nitrite, a food additive, and considering its effect on the morphological characteristics and properties of TPS/PBAT blends. TPS/PBAT/sodium nitrite (TPS/PBAT/N) blends with a TPS:PBAT weight ratio of 40:60 and sodium nitrite concentrations of 0.5, 1, 1.5, and 2 wt% were prepared by extrusion and then blown into films. The acids generated from the sodium nitrite during extrusion led to the molecular weight reduction of starch and PBAT polymers, causing the increased melt flow ability of the TPS/PBAT/N blends. The incorporation of sodium nitrite improved the blends' homogeneity and the compatibility between the TPS and PBAT phases, resulting in the increased tensile strength, extensibility, impact strength, and oxygen barrier properties of the TPS/PBAT blend film.

Organic gelatin-coated ZnNPs for the production of biodegradable biopolymer films

Petroleum-based polymers have raised significant environmental concerns. It is critical to create compostable, good biocompatibility, and nontoxic polymers to replace petroleum-based polymers. Thus, this research was performed to extract the gelatin from fish waste cartilage and coated it over the surface of spherical shaped pre-synthesized ZnNPs along with a suitable plasticizer to produce the biodegradable film. The presence of gelatin on the surface of ZnNPs was first confirmed using UV-visible spectrophotometers, as well as the characteristic functional groups involved in the coating were investigated using Fourier-Transform Infrared Spectroscopy (FTIR). The morphological appearance of gelatin coated ZnNPs was ranged from 41.43 to 52.31 nm, the shape was found as platonic to pentagonal shape, and the fabricated film was observed through Scanning Electron Microscope (SEM). The thickness, density, and tensile strength of fabricated film were found to be 0.04-0.10 mm, 0.10-0.27 g/cm³, and 31.7 kPa. These results imply that the fish waste cartilage gelatin coated ZnNPs-based nanocomposite can be used for film preparation as well as a wrapper for food and pharmaceutical packaging.

PBAT/PLA humic acid biodegradable film applied on solar greenhouse tomato plants increased lycopene and decreased total acid contents

This work aims to resolve residual film pollution in farmlands and improve tomato quality. The mechanical properties and degradation of PBAT/PLA lignin (MZS) and PBAT/PLA humic acid (FZS) composite biodegradable film were analyzed, and its effect on soil temperature and humidity, soil microorganisms, soil physical and chemical properties, tomato yield, and quality was studied. Polyethylene film (PE) was used as a control. The results demonstrate a higher degradation degree of FZS film than of MZS film. The degradation degree of FZS and MZS films reached level 2 and level 1, respectively, after 131 days of film covering. The weight loss rate of FZS and MZS films reached 52.74 % and 57.82 %, respectively, when buried for 160 days. Compared to the coverings of PE and MZS films, FZS film could significantly increase the soil's electric conductivity and organic matter content (p < 0.05). The relative abundance of soil fungi Chaetomium also increased. The yield, soluble solids, vitamin C (Vc), soluble sugar, and lycopene of tomato plants covered with FZS film significantly increased by 6.74 %, 8.75 %, 15.41 %, 8.30 %, and 27.27 % compared to plants covered with PE film, and the total acid and hardness significantly decreased by 24.95 % and 8.46 %, respectively (p < 0.05). Using 10 μm PBAT/PLA humic acid biodegradable film for tomato cultivation in autumn and winter increased the lycopene and decreased the total acid content by changing the soil's physical and chemical characteristics and increasing the content of Chaetomium soil.

Physico-chemical and antimicrobial characteristics of novel biodegradable films based on gellan and carboxymethyl cellulose containing rosemary essential oil

The purpose of the current investigation was to produce a novel functional composite biodegradable film by Gellan (Gla) and Carboxymethyl cellulose (CMC) biopolymers containing rosemary essential oils (REO) and evaluate their physicochemical and antimicrobial features. The film containing 5 % REO, due to its better mechanical properties (UTS = 13.44 ± 0.30 Mpa and SB = 21.14 ± 1.15 %) compared to other emulsified samples containing REO, was selected as the optimal film. Furthermore, it had less water vapor permeability (WVP = 6.60 ± 0.31 (g/mhPa) × 10^-8) in comparison to control sample (8.21 ± 0.10 (g/mhPa) × 10^-8) and the best color properties among the samples. The Scanning Electron Microscopy (SEM) images didn't show the phenomenon of agglomeration and point accumulation of REO. Also, 5 % of REO contributed to the increased compactness of the film in comparison to the film without the REO. Based on the results of Fourier-transform infrared spectroscopy (FTIR) spectra, no new chemical bonds were created by adding REO to the biopolymer substrate, and the REO was well dispersed and distributed among the Gla-CMC chains throughout the film substrate. Adding 5 % REO showed antioxidant effects. Considering the antimicrobial tests, all films containing REO had antimicrobial effects against the Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas fluorescens bacterial strains.

Investigation of the mixing ratio of quince seed gum, potato starch and gellan gum on the properties of the resulting film by Mixture Design

In this study, the impact of three different biopolymers, namely, quince seed gum, potato starch and gellan gum, at levels of zero to three, on optimizing the biodegradable film was investigated. In order to prepare the mixed edible film, the textural properties of the films, water vapor permeability, water-solubility, transparency, thickness, color parameters, acid solubility and microstructure of the made films were investigated. Numerical optimization of method variables was performed based on the maximum Young's modulus and minimum solubility in water, minimum solubility in acid and minimum water vapor permeability by mixed design, using the Design-Expert software. The results showed that the increase of the quince seed gum directly affected the Young's modulus, tensile strength, elongation to break, solubility in acid, and a* and b* values. However, the rise of the potato starch and gellan gum levels increased the thickness, solubility in water, water vapor permeability, transparency, L* value and Young's modulus, tensile strength, elongation to break, solubility in acid and a* and b* values. The optimal conditions for the production of the biodegradable edible film were selected at the levels of 1.623 %, 1.637 % and 0 % for quince seed gum, potato starch and gellan gum, respectively. The results of scanning electron microscopy showed that the film had more uniformity, coherence and smoothness, as compared to other films studied. The results of this study, thus, showed that there was no statistically significant difference between the predicted and laboratory results (p < 0.05), indicating the good fit of the model designed for producing a quince seed gum/potato starch/gellan gum composite film.

Enhanced antimicrobial and antioxidant properties of Nano chitosan and pectin based biodegradable active packaging films incorporated with fennel (Foeniculum vulgare) essential oil and potato (Solanum tuberosum) peel extracts

Active packaging materials are generally prepared by incorporating antimicrobial agents. The main objective of the present research is the development and characterization of active packaging with Nano chitosan and pectin. Active packaging film was prepared by incorporating essential oil of Fennel (EOF) along with potato peel extract (PPE) to improve the antioxidant and antimicrobial property of the film. Incorporation of EOF into Nano chitosan and pectin-based films increased antimicrobial activity, whereas; PPE increased the antioxidant property of the films. In the present study, thickness, optical property, mechanical property, antioxidant and antimicrobial property, total soluble matter, morphological study, FTIR analysis, and microbial degradation study of the prepared active packaging material was done. The addition of the PPE and EOF together improved the surface, optical, mechanical, antimicrobial and antioxidant properties of the packaging film. Enhanced antimicrobial and antioxidant property of the Nano chitosan-PPE-PVA-EOF and pectin-PPE-PVA-EOF-based packaging films can extend the shelf life of the packed food; hence it is suggested for the active packaging for perishable food commodity. In short, the prepared active packaging film with biodegradable property is suggested as an effective packaging material to replace synthetic plastic packages for food and hence reduce plastic pollution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05333-9.

Production and characterization of biodegradable bi-layer films from poly(lactic) acid and zein

Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.

Cassava starch films for food packaging: Trends over the last decade and future research

Cassava starch is one of the most available and cost-effective biopolymers. This work aimed to apply a bibliometric methodology to identify the most impactful scientific data on cassava starch and its residues for food packaging in the last ten years. As a result, an increasing interest in this subject has been observed, mainly in the past five years. Among the 85 selected scientific publications, Brazil and China have been leading the research on starch-based films, accounting for 39 % of the total. The International Journal of Biological Macromolecules was the main scientific source of information. Besides cassava starch, 41.18 % of these studies added other biopolymers, 5.88 % added synthetic polymers, and 4.71 % added a combination of both. Studies analyzed suggested that different modifications in starch can improve films' mechanical and barrier properties. In addition, 52.94 % of articles evaluated the film's bioactivity. Still, only 37.65 % assessed the performance of those films as food packaging, suggesting that more studies should be conducted on assessing the potential of these alternative packages. Future research should consider scale-up methods for film production, including cost analysis, assessment life cycle, and the impact on the safety and quality of a broader range of foods.

Preparation of green film with improved physicochemical properties and enhanced antimicrobial activity using ingredients from cassava peel, bamboo leaf and rosemary leaf

Persistent petroleum based plastic polymers are posing a threat to the environment and human health. Hence, preparation of eco-friendly packaging materials from natural sources is innovative idea to replace persistent plastic films. However, biodegradable films from biomass absorb water that can promote bacterial growth and affect lifetime of film as well as the packed products. In this work, new biodegradable film with improved antimicrobial activity, physicochemical property and less water absorbing and holding property is prepared from modified blend of cassava peel starch (CPS), silica nanoparticle (SNP), glycerol plus rosemary essential oil (REO). The mixture (blend) of CPS, SNPs and glycerol in measured amount of distilled water was treated with acetic anhydride to reduce hydrophilic nature of the blend before adding REO. The content of SNPs in the biofilm was optimized by varying the concentration of SNPs (0.2–0.8%; w/w) keeping other factors constant. Based on the characterization results, the physicochemical property of the biofilms was dependent on the content of SNPs and the best result (film) has been found with 0.6% SNPs which was considered as optimum amount for further experiments. The film prepared from modified blend with 0.6% SNP had shown low water absorption, low water vapor transition rate, improved thermal stability, and less biodegradability. Based on the image from profilometer, the modified blend had shown better homogeneity with REO than unmodified blend and the film with REO had shown better antimicrobial activity as compared to the film without REO (control). The antimicrobial activity of the film with REO was also compared with reference (gentamicin) and its activity was comparable and promising. In general, the prepared film had shown improved physicochemical properties and enhanced antimicrobial activity.

Characterizations and antibacterial activities of passion fruit peel pectin/chitosan composite films incorporated Piper betle L. leaf extract for preservation of purple eggplants

The present study aimed to synthesize biodegradable films based on crosslinked passion fruit peel pectin/chitosan (P/CH) films incorporated with a bioactive extract from Piper betle L. leaf, and investigate their morphological, mechanical, water vapor permeability, optical, and antibacterial properties. The thickness and water vapor permeability of P/CH blend films were proportional to the increasing concentration of Piper betle extract (PB). The tensile strength of P/CH/PB films was significantly reduced at 42.89% compared to the P/CH films. The morphological characterization affirmed that resultant blend films showed a well-organized homogeneous structure with no cracks. Moreover, the antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, and Klebsiella pneumoniae increased with the increased concentration of PB in the obtained films. Our results demonstrated that P/CH/PB blend films could be potentially used for food packaging applications.

Preparation of the alginate/carrageenan/shellac films reinforced with cellulose nanocrystals obtained from enteromorpha for food packaging

Enteromorpha prolifera belonging to the chlorophyta phylum is the main pollutant of "green tide", and propagates rapidly in recent years. However, there is almost no high-value enteromorpha treatment method at present. This study aimed to extract cellulose nanocrystals (CNC) from enteromorpha and prepare the CNC reinforced films based on alginate, carrageenan and shellac for food packaging. The effects of alginate, κ-carrageenan, cellulose nanocrystals and glycerin on the CNC reinforced alginate/carrageenan films (AC films) properties were studied systematically in this work. The results showed that the mechanical properties, swelling properties, and barrier properties of the AC could be adjusted by the concentrations of the different components. In addition, response surface methodology (RSM) was used to optimize the formula of the AC used for food packaging according to the requirements of the practical application. Furthermore, in order to further improve the food packaging capacity of the composite films, shellac was added to the optimized alginate/carrageenan films (OAC films) to obtain the shellac optimized alginate/carrageenan films (SOAC films). Finally, the OAC films and SOAC films showed excellent properties to extend the storage time of chicken breast and cherry tomatoes in the food storage experiment.

Degradation characteristics of biodegradable film and its effects on soil nutrients in tillage layer, growth and development of taro and yield formation

This study investigated the degradation characteristics of different biodegradable film and its effects on soil nutrients in tillage layer, growth and development of taro and yield formation. Field experiment with biodegradable films, including poly-(butylene adipate-co-butylene terephthalate) PBAT, (poly-carbon dioxide) PCO2, (poly propylene carbonate) PPC, as well as common mulch film (CK1) and uncovered mulch film (CK2) were conducted on Longxiang taro in 2020 and 2021 respectively. The degradation rate of the three biodegradable films was PBAT > PPC > PCO2. Compared with CK1, the alkali-hydrolyzed N of PBAT at the growth stage and fruiting stage significantly increased in 2020 and 2021, respectively (both, P < 0.05). The average content of available P of PPC at seedling stage was higher than that in PCO2, and CK1 was significantly decreased compared with that in CK2 (all, P < 0.05). The content of soil available K and organic matter in different growth stages of taro in all film mulching treatments were decreased in comparison to CK2. Moreover, compared with CK2, PCO2 biodegradable film significantly increased plant height at seedling and growth stage, stem diameter at growth stage, and leaf area index at fruiting stage (all, P < 0.05). Similarly, the yield of mother and filial bulbs of PPC, PCO2 and PBAT were significantly higher than those of CK2 in 2020 and 2021, respectively (all, P < 0.05). However, no significant differences were found in starch, polysaccharide and protein contents among different treatments. The three biodegradable films, especially PCO2, can significantly affect soil nutrient content, promote plant growth and improve taro yield.

Effect of the addition of Euterpe oleracea Mart. extract on the properties of starch-based sachets and the impact on the shelf-life of olive oil

This study aimed to produce and characterized active biodegradable packages by extrusion of cassava starch, biodegradable polyester, plasticizer, and acai extract (EA 0, 1, 2, 3 and 4%) and to evaluate its effects on extra virgin olive oil (EVOO) for 120 days. All analyses were performed at the beginning (day 0) and the end of the experiment (day 120). The oil was characterized for acidity index (IA), peroxide index (IP), thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), phenolic compounds (PC) and color parameters. The incorporation of EA at the initial time caused increased thickness, mechanical properties, solubility in water and oil in all formulations. The some values of properties increased or decreased, due to the interaction of the stored product and packaging. At the end of the storage period, the values of IA and IP were below the limits established by current legislation. The EVOO showed a gradual decrease in PC from day 1 to day 120, for all treatments.

Ultrasound-assisted preparation of chitosan/nano-silica aerogel/tea polyphenol biodegradable films: Physical and functional properties

In this study, chitosan(CS), nano-silicon aerogels(nSA) and tea polyphenols(TP) were used as film-forming materials and processed with ultrasonication to form films using the tape-casting method. The effects of ultrasonication time, temperature and frequency on the properties of CS/nSA/TP film were explored via material property testing. The results of response surface showed that the maximum tensile strength of the film was 4.036 MPa at ultrasonication time(57.97 min), temperature(37.26 °C) and frequency(30 kHz). The maximum elongation at break of the film was 279.42 % at ultrasonication time(60.88 min), temperature(39.93 °C) and frequency(30 kHz). Due to cavitation and super-mixing effects, ultrasonication may make the surface of the film smoother and easier to degrade. After ultrasonication, TPs were protected by the 3D network structure composed of CS and nSA. Ultrasonication improved the antioxidant and antibacterial properties of the film. These results show that ultrasonication is an effective method to improve the properties of films.

Production of chitosan-based biodegradable active films using bio-waste enriched with polyphenol propolis extract envisaging food packaging applications

Developing biodegradable active films has been a promising green approach to overcoming global concerns over the environmental pollution and human health caused by plastic utilization. This study aimed to develop active films based on chitosan (CS), produced from waste crayfish (Procambarus clarkii) shells enriched with bioactive extract (5-20%) of propolis (PS) and to characterize its properties, envisaging food packaging applications. The chromatographic profile of PS extract confirmed its richness, with 41 phenolic compounds. With increasing extract addition to the chitosan, the thickness of the films increased from 61.7 to 71.7 μm, causing a reduction in the light transmission rate, along with a greenish colour shift. The interactions between PS extract and CS was confirmed by infrared spectroscopy, at the same time that the microstructural integrity of the films was checked on the scanning electron microscopy micrographs. The findings also showed that addition of PS enhanced the films thermal stability and mechanical properties e.g., tensile modulus, yield strength, and stress at break. Besides, it improved the antioxidant and antimicrobial activities. Overall, CS-based composite films seem a promising green alternative to petroleum-based synthetic plastics allowing to extend the shelf life of food products due to their eco-friendly nature.

Effect of chitosan grafting oxidized bacterial cellulose on dispersion stability and modulability of biodegradable films

Bacterial cellulose (BC) is a kind of high-purity cellulose biomaterial with a unique three-dimensional structure. To improve the mechanical properties and reinforce the BC composite films, in this study, we provide in detail a simple, fast, and environmentally-friendly method to prepare a biodegradable composite film using chitosan (CS) with different molecular weights and BC with excellent dispersion. The water moisture content (MC), water solubility (WS), contact angle (CA), mechanical properties and barrier properties were measured to assess the effect of CSn-OBC composite films. The morphology, structural and thermal properties of the films were evaluated by scanning electron microscopy, spectral analysis, thermogravimetry and X-ray diffraction. Results showed that the biodegradable film prepared by grafting chitosan with high molecular weight and uniformly dispersing bacterial cellulose exhibited superior mechanical properties, water resistance, and thermal stability, which are essential characteristics for commercial applications in complex environments.

Intelligent pH-sensing film based on jaboticaba peels extract incorporated on a biopolymeric matrix

Food spoilage is associated with pH change. Thus, the aim of this study was to develop a pH-sensing film based on the addition of anthocyanin extracted from jaboticaba peel to a biopolymeric matrix. UV-Vis spectroscopy analysis of the anthocyanin extract was performed to detect the color change in a broad pH range (1-11). Also, the thermal properties, morphology, moisture content (MC), water solubility (WS), water vapor permeability (WVP) and release test results were examined. The applicability of the pH-sensing film as intelligent packaging was tested by monitoring milk spoilage. Results showed that the film developed has satisfactory thermal stability up to 200 °C. Also, the MC and WVP properties of the film were reduced when the anthocyanin extract was present, 11.5% and 6.5 × 10^-10 g H₂O Pa^- 1 s^-1 m^-1, respectively, while the WS showed an increase (54.33%). Release tests showed remarkable performance in simulated alcoholic and fatty aqueous foods. The food application test demonstrated the potential use of the anthocyanin-based film as a food quality indicator due to film visual color change ( Δ E >10, after 8 days of milk spoilage monitoring).

Effects of biodegradable film mulching on bacterial diversity in soils

The spread of biodegradable plastic films (BDFs) not only increases grain yield but also reduces environmental pollution from plastic film to a large extent. Soil microbes are considered to be involved in biodegradation processes. However, the study of microbe diversity in soil mulched with biodegradable plastic film remains limited. Here, we compared the diversity of microbes between soils with biodegradable film and nonbiodegradable film (NBDF) mulch. The results showed that BDFs affected total C, P and NH₄⁺-N, especially organism C content, as well as microbe species richness (ACE; Chao1) and diversity (Simpson index; Shannon index). In terms of dominant phyla and genera, BDFs and NBDF can influence the abundance of disparate species. Furthermore, BDFs could also contribute to improving the richness of the important functional bacterial groups in soil, e.g., Pedomicrobium and Comamonas, both of which are involved in the degradation of plastic residues in soil. Finally, we found that BDFs improved the transformation of nitrogen by significantly increasing the abundances of Nitrobacter and Nitrospira. Our results highlight the impact of BDF mulch on the abundance of functional bacteria in the soil.

Characterization and properties of singly and dually modified hydrogen peroxide oxidized and glutaraldehyde crosslinked biodegradable starch films

Poor properties of native cassava starch film such as low mechanical properties and high water uptake are the limitations of biodegradable starch films. Dual modification is an alternative way to improve the properties. Characteristics and properties of oxidized, crosslinked and dually modified starch films by hydrogen peroxide oxidation and glutaraldehyde crosslinking were examined. Sequence of the dual modification was also studied. All starch films were prepared by casting technique using glycerol plasticizer. The oxidation and crosslinking of modified starch were confirmed by carbonyl and carboxyl contents as well as degree of crosslinking. The lowest and highest molecular weights of the modified starch were observed for the oxidized starch and crosslinked starch, respectively. Moreover, swelling power and moisture absorption of dually modified starch films was clearly lower than those of singly modified films. Additionally, both good stiffness and extensibility was also obtained from the dually modified films especially for the crosslinked-oxidized film. Moreover, thermal property and biodegradability were also determined.

Degradable photo-crosslinked starch-based films with excellent shape memory property

With the increasingly serious plastic pollution, people's demand for the multi-functional biodegradable plastics is becoming more and more urgent. Inspired by the crosslinked shape memory polymers, the crosslinked starch films were synthesized by inducing the decomposition of benzophenone into free radical and depriving hydrogen on starch macromolecules under UV irradiation, in order to gain a high shape memory performance. The results showed that a three-dimensional crosslinking network between starch macromolecule chains was formed. Compared with the uncrosslinked starch films, the photo-crosslinked films not only had higher mechanical property (tensile strength increased by 154%), but also had better water resistance (water contact angle from 60° to 87°) due to the reduction of free hydroxyl groups. In addition, the stable covalent bonds serving as netpoints endow photo-crosslinked films with great improvement in shape memory property, with nearly 180° bending recovery. More importantly, the maximum shape memory fixity ratio (R_f) and shape memory recovery ratio (R_r) under stretch deformation were 96.5% and 99.8%, respectively. And the R_f and R_r could reach 94.6% and 79.8% even at higher strain. In all, the excellent shape memory performance and good degradability crosslinked starch films, which have great potential application in disposable heat-shrinkable packaging materials.

Property improvement of biodegradable citric acid-crosslinked rice starch films by calcium oxide

Due to several important limitations for packaging applications of starch film such as strength and hydrophilicity, rice starch (Oryza sativa) film was crosslinked with citric acid and modified by different contents of calcium oxide. FTIR spectra showed the evidence of crosslinking by citric acid and the presence of calcium oxide in the modified rice starch films. After the crosslinking, the decrease of degree of crystallinity and swelling including the increase of film smoothness and strain at maximum load were observed. The application of both citric acid and calcium oxide caused greater decrease of swelling, moisture uptake as well as higher stiffness and antibacterial activity than those of the use of only the citric acid. The highest stiffness and antibacterial activity were found for the crosslinked film added by 5 wt% calcium oxide. Moreover, the effect of calcium oxide contents on morphological, thermal and biodegradable properties of the crosslinked films was also investigated.

Effect of glycerol concentration and carboxy methyl cellulose on biodegradable film characteristics of seaweed waste

Eucheuma cottonii waste seaweed has high cellulose content. Therefore, it could be potentially used as a raw material for biodegradable films to replace plastic. A plastic film is its moisture resistance, and this property allows plastic films to be used as packaging materials and biodegraded by microbes. This research aims to obtain a concentration of glycerol and Carboxy Methyl Cellulose (CMC) to obtain the best biodegradable film characteristics from E. cottonii seaweed waste. This study was conducted in factorial by using a complete randomized block design with two factors: glycerol concentration and CMC concentration. Each treatment has three levels and three replications (3 × 3). The first factor was glycerol concentration: 0.25% (G1), 0.5% (G2), and 0.75% (G3). The second factor included concentrations of 1% CMC (C1), 2% CMC (C2), and 3% CMC (C3). Then, Tensile Strength (TS), thickness, solubility, and elongation were observed. Functional group analysis was conducted by Fourier-transform infrared spectroscopy and biodegradability test. The results showed that the addition of glycerol concentrations of 0.5 and 0.7% and CMC from 1 to 3% produced tensile strengths of 23–39 MPa. These values are proportional to the tensile strength of Poly Tetra Fluoro ethyne (PTFE) and Poly Propylene (PP) synthetic plastics released by Dotmar Engineering Plastics. The biodegradability test showed that the produced biodegradable films decomposed after 14 days.

Preparation and characterization of a novel biodegradable film based on sulfated polysaccharide extracted from seaweed Ulva intestinalis

Seaweeds can be a suitable, inexpensive, abundant, and renewable source for the production of biodegradable films as an alternative to plastics. Sulfated polysaccharides, which are abundant in Ulva intestinalis seaweed, have shown important biological activities such as anticoagulant, antioxidant, antitumor, anti-inflammatory, and antiviral activities. Mechanical, physicochemical, barrier, and surface properties of sulfated polysaccharide films extracted from Ulva intestinalis using glycerol and polyethylene glycol (PEG) as plasticizers were studied. Ulva intestinalis sulfated polysaccharide films (USP films) were successfully prepared by the incorporation of three concentrations of plasticizers (30, 40, and 50%). The film properties depended on the type and concentration of the plasticizer. Based on the results, by increasing the concentration of the plasticizer, the thickness, moisture content, solubility, and elongation at break of the USP films increased and tensile strength, young's modulus, transparency, and barrier properties of the films decreased. The film plasticized with 30% PEG showed the highest value of tensile strength (36.95 MPa), and the lowest value for permeability to vapor water and oxygen were 1.9 g mm-1 s-1kPa-1 × 10-11 and 7.45 cm-3.cm/cm2.s.cmHg ×10-8, respectively. Scanning electron microscopy (SEM) observations indicated that the surface of the films was free of bubbles, cracks, or fractures. Fourier transform infrared (FTIR) spectroscopy results revealed some interactions between plasticizers and the polymer.

Film production with flaxseed mucilage and polyvinyl alcohol mixtures and evaluation of their properties

Flaxseed mucilage was extracted with distilled water, dried and used for film production with polyvinyl alcohol (PVA) (ratio 1:1) of different hydrolysis degrees (88.0 and 98.3%). The properties of the films were evaluated by determining the thickness, tensile measurements, moisture content, water vapor permeability, apparent opacity, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) analysis and thermogravimetric analysis. Flaxseed mucilage, when mixed with PVA, produces less resistant, less rigid, more-flexible films, has a higher thermal stability, and does not change the water vapor barrier properties compared with pure mucilage films. SEM revealed that films with mucilage and PVA mixtures formed a compact and homogeneous structure, corroborating the FTIR spectra that indicated a chemical interaction between these two biopolymers. In general, the degree of PVA hydrolysis did not influence the properties of the films when mixed with flaxseed mucilage extract. Therefore, films obtained from mixtures of flaxseed mucilage and PVA can be an interesting and advantageous alternative for producing bio-based packaging.

Biodegradable film for raisins packaging application: Evaluation of physico-chemical characteristics and antioxidant potential

The objective of this study was to evaluate the application of a biodegradable film, based on grape seed flour extract, for raisin packaging. Physico-chemical characteristics (moisture, total soluble solids, total acidity, pH), total phenolic content and antioxidant activity were evaluated during 182 days of storage at 20 °C, compared to a poly(ethylene) film packaging. After 182 days, the use of biodegradable film increased raisin moisture and pH, decreased total soluble solids and total acidity of raisin compared to the use of poly(ethylene) film. The total phenolic content and antioxidant activity of raisin packed in the biodegradable film were 60.0 and 51.8% higher, respectively, than in poly(ethylene) film. The results showed that the biodegradable film based on seed flour extract is a potential material for active packaging due its contribution to the maintenance of the antioxidant activity of raisin and can be used for their conservation.

Development and characterization of chitosan and acrylic acid-based novel biodegradable polymeric films for soil conditioning

In this study, biodegradable polymeric films (BPFs) based on chitosan and acrylic acid cross-linked with 3-aminopropyl triethoxysilane (APTES) were developed for water retention and soil-conditioning applications in areas sufferings from water scarcity. A series of BPFs were prepared by varying the amount of silica nanoparticles (SiNPs) (0.67% to 2.6%) and a correlation of the optimum amount of SiNPs with thermal stability, morphology, swellability (at various pH), degradability, and anti-microbial activity were deduced. The obtained results showed that the NP 8 (containing 2.51% of SiNPs) exhibited the maximum absorption capacity (1815%) in distilled water, whereas NP6 (including 1.88% of SiNPs) expressed the maximum thermal stability (T_50% at 375.61 °C). The microscopic images further strengthen this observation because the maximum number of micro-porous cavities was shown on the surface of NP8. The time-dependent swelling response in distilled water accomplished that hydrophilicity (percentage swelling) of films was enhanced with an increase in the concentration of SiNPs. All BPFs samples exhibited inhibitory response against both gram-positive (for Staphylococcus aureus was 2.9 cm for NP6) and gram-negative (for Escherichia coli was 0.9 cm for NP8) bacteria. The biodegradation test inferred that the degradation of BPFs in soil did not affect the soil fertility as nano-silica is proven as growth-promoting miniatures. It can be concluded that these BPFs may be efficiently employed in the agriculture sector for water retention and as a soil conditioner.

Physicochemical characterisation of Salvia macrosiphon gum based edible films incorporated with various fatty acids

In the present study, the influence of different concentrations of three fatty acids (palmitic, stearic, and oleic acids) on improving the physicochemical, barrier, mechanical, thermal and surface properties of Salvia macrosiphon seed gum (SSG) edible films was investigated. The results revealed that the selected fatty acids promoted an increase in hydrophobicity of SSG films; characterized by significantly lower moisture uptake, solubility, water vapour permeability, and considerably higher contact angles. The opacity and tensile strength of SSG films increased by addition of the fatty acids, while elongation at break decreased. The estimated values of surface free energy inferred that dispersive component of surface energy increase by incorporation of the fatty acid, whereas its polar component decreased. Among the selected fatty acids, the efficiency of oleic acid on improving the characteristics of films was higher than saturated fatty acids, i.e., palmitic and stearic acids. Concluding, incorporation of fatty acids to SSG films seems to be necessary to fabricate films with lower affinity to water, especially for those applications that require less hydrophilic films.

Biodegradable film based on pectin/Nano-clay/methylene blue: Structural and physical properties and sensing ability for measurement of vitamin C

In this study, biodegradable film based on pectin modified with Nanoclay and methylene blue was prepared. The Physicomechanical properties of the prepared film, including: thickness, water solubility, water vapor permeability (WVP), antioxidant activity and color properties were investigated. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC) and texture analysis techniques were used to investigate the physical and mechanical properties of the films. The optimum Pec/Clay/MB film was used as a colorimeter sensor to detect and measure vitamin C. The results showed that the addition of Nanoclay to the film increased the thickness and decreased the solubility of water and reduced the WVP. The addition of methylene blue had no significant effect on the thickness, but increased water solubility and increased antioxidant activity. The addition of Nanoclay increased the tensile strength (TS) of the film, but decreased its elongation at break (EB). The addition of Nanoclay increased the melting temperature of the film and decreased its crystallization temperature. In the SEM images, the clay particles at 50-100 nm in the film structure were characterized. Nanoclay and methylene blue reduced the surface cleavage of the film. Pec/Clay/MB film color was changed from blue to colorless in the presence of vitamin C. The linear range of vitamin C measurement was 10 to 500 and the detection limit was 10. By detecting the color changes of the film in the presence of vitamin C, the amount of this vitamin was measured in orange, kiwi and tangerine juice. The accuracy of the data was evaluated by the titration method. The sensor accuracy was obtained over 90%.

Starch-based nanocomposites with cellulose nanofibers obtained from chemical and mechanical treatments

Cellulose nanofibers (CNFs) were isolated from unripe banana peel by acid hydrolysis, with different acid concentrations (0.1%, 1.0% and 10% v/v), followed by mechanical treatment with high-pressure homogenizer. Banana starch-based films added with CNFs (0.2% w/w) as a reinforcing agent were produced by the casting method. The rheological behavior of aqueous dispersions of CNFs (1.0% w/w) and their effects on the properties of nanocomposite films were investigated. All aqueous dispersions of CNFs showed gel-like behavior and, when incorporated to the films, CNFs improved their water barrier properties and mechanical resistance as demonstrated by the increase in tensile strength and Young's modulus. Moreover, CNFs were well dispersed in the composite matrix. CNFs prepared at higher concentration, followed by mechanical treatment (FNM1 and FNM10), formed films with low moisture (13.66%) and solubility in water (24.1%). Whereas, CNFs prepared at the lowest acid concentration without mechanical treatment (FN0.1) led to films with high elongation at break (30.6%) and good tensile strength (12.3 MPa). Regardless of the used CNFs, all the nanocomposites displayed lower UV/light transmission than control film. The nanocomposite has potential use in food packaging, since the use of CNFs can promote improvements on barrier, optical and mechanical properties. Cellulose nanofibers isolated from agro-industrial residues offer the potential to reinforce composites of biodegradable polymers, producing a value-added material.

Biodegradable films based on fruit puree: a brief review

The production of fruit-film packaging has attracted increasing attention in scientific research due to the packaging's environmentally friendly, nontoxic, and edible characteristics. The development of alternative packaging contributes to both minimizing the environmental impacts caused by the large consumption of non-biodegradable plastics and favoring the reduction of postharvest loss/waste of fruit. In addition, these fruit films have the potential to be functional packages due the presence of antioxidant and antimicrobial compounds that can migrate to the food matrix, acting as natural additives. The use of fruit puree to develop biodegradable films can be simpler and more practical than the developed of films from fruit flour or extracts, reducing the time, energy, and resources necessary to prepare the film-forming solution. A better understanding of the mechanical properties, bioactive compounds, and potential applications is interesting in terms of prospecting new specific ways to produce and use these films. In this study, we briefly review the general aspects of fruit puree films, highlighting their characterization for use as food packaging.

Agar-based edible films for food packaging applications - A review

Agar is a biopolymer extracted from certain red algae. The continuous and transparent film made from agar gum is becoming a common and renewable alternative for plastic-based food packaging materials. However, plain agar film suffers from brittleness, high moisture permeability, and poor thermal stability. Considerable researches have been devoted to improving the properties of agar films to extend their applications. These include reinforcements by nanomaterials, blending with other biopolymers, and incorporating plasticizers, hydrophobic components, or antimicrobial agents into their structure. This article comprehensively reviews the functional properties and defects of edible films made from agar gum. Also, it describes various strategies and components used to make an agar film with desirable properties. Moreover, the applications of agar-based edible films with improved functionality for food packaging are discussed.

Morphological and physical properties of kefiran-whey protein isolate bionanocomposite films reinforced with Al2O3 nanoparticles

Considering environmental pollution caused by the non-biodegradable polymers used in food packaging, developing and enhancing the properties of biodegradable films seem to be necessary. For this aim, in the present study, kefiran-whey protein isolate bionanocomposite films were prepared and the impact of different concentrations (1, 3 and 5% w/w) of Al₂O₃ (alumina) nanoparticles on their physical, morphological, thermal and mechanical properties was studied. Based on the obtained results, an increase in the nanoparticles content led to a significant decrease (p < 0.05) in the water vapor permeability, moisture absorption, moisture content, and water solubility. Scanning electron microscope images showed a homogeneous structure, confirming the good dispersion of alumina nanoparticles with smooth surface up to concentration of 3%. In addition, both thermal stability and mechanical properties of the films were improved by the increased concentrations of alumina. The results of X-ray diffraction indicated that the intensity of the crystalline peaks of film increased with the addition of Al₂O₃ to kefiran-whey protein isolate matrix. By considering all results, the concentration of 3% was proposed as the appropriate concentration of Al₂O₃ for the nano-reinforcement of kefiran-whey protein isolate bionanocomposites.

Development and characterization of a novel edible film based on Althaea rosea flower gum: Investigating the reinforcing effects of bacterial nanocrystalline cellulose

Althaea rosea flowers were used to procure the gum (ARG) needed for film preparation. Pretest studies suggested 1.5% ARG + 50% glycerol as optimum for film preparation. The reinforcement impact of 3, 5, and 8 wt% bacterial nanocrystalline cellulose (BNC) incorporation (based on the dry weight of ARG) was investigated on the structural, mechanical, physical, thermal, optical, morphological, and barrier properties of films. The Results suggested that increasing the BNC concentration until a certain level (5 wt% BNC) could improve the latter properties. However, at higher concentration (8 wt% BNC), cellulose nanoparticles tended to agglomerate, which led to the impairment of some of those properties, especially barrier properties. According to AFM and SEM results, BNC addition increased surface roughness and coarseness. All BNC-loaded films showed better functions compared to control sample (0 wt% BNC) and the film containing 5 wt% BNC was suggested as the optimum film.

Characterization of curcumin incorporated guar gum/orange oil antimicrobial emulsion films

Edible films are manufactured from natural, renewable, nontoxic, and biodegradable polymers and are safe alternatives to plastic food packaging. Despite ongoing research, biopolymer-based edible films still are not at a quality to ensure total commercial replacement of synthetic packaging materials. The study aims to compare the effectiveness of some novel methods employed to improve edible film properties. These include dispersion of orange oil (1% & 2% v/v) and/or curcumin into guar gum (GG), glycerol and lecithin-based edible films that are further reinforced with Sodium trimetaphosphate (STMP) crosslinking with the aim enhancing films physical properties. The films were characterized by measurement of film thickness, density, moisture content, water dissolvability, FTIR Spectroscopy, opacity, water vapor permeability, tensile properties, and antimicrobial activity. Orange oil and curcumin preserved their antimicrobial activity inside the films, which bestowed the films with an active packaging function. Control GG films had acceptable tensile and barrier properties that were further improved. All other film properties, such as opacity, dissolvability, and moisture content, that should be designed for specific application, were successfully modified with the methods used. Our results confirm successful application of STMP crosslinking, emulsion film formation, and active agent addition to edible films in manufacturing GG films for packaging.

Physicochemical properties of the edible films from the blends of high methoxyl apple pectin and chitosan

Chitosan (CH) and pectin (PE) are considered as promising biomaterials in developing eco-friendly films due to their film-forming, biodegradable, and non-toxic characteristics, the films from pure CH or PE have obvious defects such as poor barrier and mechanical properties. In this study, the blend films of CH and PE at varying mass ratios were characterized. Structurally, numerous small pores evenly distributed in PE film while big caves unevenly scattered in CH film. CH film is semicrystalline but PE and blend films are totally amorphous, the two individual films presented comparable values in water content and solubility to blend films. The CH film showed lower water vapor permeability and surface wettability and these parameters of the blend films decreased with CH level, the blend films exhibited high transparence as PE film did, which is much higher than that of CH film. Mechanically, the PE film presented higher values in stretchability and tensile strength than CH film. Moreover, in a different blending ratios, synergistic effects were found with several characters of the CH/PE blend film, especially in transparence and mechanical properties. These synergistic effects were ascribed to the intermolecular electrostatic interactions between CH and PE.