Enhanced antifungal properties of poly(butylene succinate) film with lignin nanoparticles and trans-cinnamaldehyde for mango packaging.

Sustainable poly(butylene succinate) (PBS) films incorporating lignin nanoparticles (LN) and trans-cinnamaldehyde (CN) have been developed to preserve mango freshness and provide food safety. PBS/LN, PBS/CN, and PBS/LN/CN composite films were produced by blown film melt extrusion. This study investigated the effect of CN-LN on the CN remaining content, thermal, mechanical, and barrier properties, diffusion coefficient, and antifungal activity of PBS films both in vitro and in vivo. Results showed that LN in the PBS/LN/CN composite film contained more CN than in the PBS/CN film. The compatibility of CN-LN with PBS produced homogeneous surfaces with enhanced barrier properties. PBS/LN/CN composite films demonstrated superior antifungal efficacy, inhibiting the growth of Colletotrichum gloeosporioides and preserving mango quality during storage. Results suggested that incorporating LN into PBS composite films prolonged the sustained release of antifungal agents, thereby inhibiting microbial growth and extending the shelf life of mangoes. Development of PBS/LN/CN composite films is a beneficial step toward reducing food waste and enhancing food safety.

Speeding it up: dual effects of biostimulants and iron on the biodegradation of poly(lactic acid) at mesophilic conditions.

Plastic pollution presents a growing concern, and various solutions have been proposed to address it. One such solution involves the development of new plastics that match the properties of traditional polymers while exhibiting enhanced biodegradability when disposed of in a suitable environment. Poly(lactic acid) (PLA) is a biobased, compostable polymer known for its low environmental impact and ability to break down into harmless components within a specified timeframe. However, its degradation in industrial composting facilities poses challenges, and it cannot degrade in home composting. In this study, we investigated the biodegradability of PLA within a biostimulated compost matrix at mesophilic conditions (37 °C) over 180 days. The compost environment was enhanced with Fe3O4 nanopowder, skim milk, gelatin, and ethyl lactate, individually and in combination, to target different stages of the PLA biodegradation process. We monitored key indicators, CO2 evolution, number average molecular weight, and crystallinity, to assess the impact of the various biostimulants and iron. The results demonstrated that the most effective treatment for degrading PLA at mesophilic conditions was adding gelatin and Fe3O4. Gelatin accelerated PLA biodegradation by 25%, Fe3O4 by 17%, and a combination of gelatin and Fe3O4 by 30%. The effect of skim milk and ethyl lactate is also reported. This research introduces novel pathways to enhance PLA biodegradation in home composting scenarios, offering promising solutions to address the plastic pollution challenge.

Accelerating Biodegradation: Enhancing Poly(lactic acid) Breakdown at Mesophilic Environmental Conditions with Biostimulants.

Poly(lactic acid) (PLA) has garnered interest due to its low environmental footprint and ability to replace conventional polymers and be disposed of in industrial composting environments. Although PLA is compostable when subjected to a suitable set of conditions, its broader acceptance in industrial composting facilities has been affected adversely due to longer degradation timeframes than the readily biodegradable organic waste fraction. PLA must be fully exposed to thermophilic conditions for prolonged periods to biodegrade, which has restricted its adoption and hindered its acceptance in industrial composting facilities, negating its home composting potential. Thus, enhancing PLA biodegradation is crucial to expand its acceptance. PLA's biodegradability is investigated in a compost matrix under mesophilic conditions at 37 °C for 180 days by biostimulating the compost environment with skim milk, gelatin, and ethyl lactate to enhance the different stages of PLA biodegradation. The evolved CO2, number average molecular weight (Mn), and crystallinity evolution are tracked. To achieve a Mn ≲ 10 kDa for PLA, the biodegradation rate is accelerated by 15% by adding skim milk, 25% by adding gelatin, and 22% by adding ethyl lactate. This work shows potential techniques to help biodegrade PLA in home composting setting by adding biostimulants.

Modulating Barrier Properties of Stereocomplex Polylactide: The Polymorphism Mechanism and Its Relationship with Rigid Amorphous Fraction.

The barrier properties of semicrystalline polymers are crucial for their performance and their use as packaging materials. This work uncovers the mechanism of polymorphism modification (α, α' and stereocomplex-crystals) and its combined effect on the oxygen and water vapor barrier properties of semicrystalline stereocomplex polylactide (SCPLA). A polymorphic selective filler-type nucleator was employed to eliminate the temperature effect on the development of polymorphism and rigid amorphous fraction (RAF), allowing correlations of barrier properties with different crystal forms and RAF combinations under the same amorphous composition (SCPLA). The oxygen and water vapor barrier performances strongly correlated with crystallinity and crystal form but were not monotonically related to the RAF quantity. The study proposes that the chain conformation of intermediate phases between the crystalline and amorphous phases differs with the associated crystal forms, thereby leading to different RAF "qualities" and contributing to different gas diffusion and solubility coefficients of the amorphous regions. RAF's per unit excess free volume may be varied with crystal forms, for instance: α' ≫ SC > α. Therefore, SCPLA with α' crystals exhibited high oxygen and water vapor permeabilities. Those with high SC and α crystals showed similar barrier behaviors governed by Henry's law dissolution and followed a linear "two-phase" relationship with total crystallinity.

Effect of Chemical and Steam Explosion Pulping on the Physical and Mechanical Properties of Sugarcane Straw Pulp Trays.

Sugarcane straw fiber (SSF) samples were prepared by chemical pulping (CP) and steam explosion (STE). CP (5, 10, 15% NaOH + 0.2% w/w anthraquinone at 121 °C for 1 h) and STE pressure (1.77, 1.96, and 2.16 MPa at 220 °C for 4 min) SSF trays were molded with a hydraulic hot-press machine at 120 °C, 7 min, and 1.72 MPa. The yield (%) of SSF from STE (54-60% dry basis (db.)) was higher than CP (32-48% db.). STE trays had greater tensile strength than CP. However, STE's elongation and compression strength was lower than CP tray samples. The trays made from SSF using STE had less swelling in thickness, longer water wetting time, and a higher water contact angle than those made from CP. The micrographs displayed a smaller size of SSF obtained in STE than the CP. The appearance and area of peaks in ATR-FTIR spectra and XRD diffractograms, respectively, revealed that the STE trays had a larger residual lignin content from the lignin study and a lower crystallinity index than the CP trays. Moreover, the lightness values of the STE trays were lower than those of the CP trays due to lignin retention. The study results indicate that CP is the preferred method for producing SSF packaging material with high flexibility and fiber purity. However, when considering the specific SF of 4.28, the STE treatment showed superior physical and mechanical properties compared to CP. This suggests that STE could be an excellent alternative green pulping technique for producing durable biobased trays. Overall, the findings highlight the potential of STE as a viable option for obtaining trays with desirable characteristics, providing a sustainable and efficient approach to tray production.

Boosting Degradation of Biodegradable Polymers.

Biodegradation of polymers in composting conditions is an alternative end-of-life (EoL) scenario for contaminated materials collected through the municipal solid waste management system, mainly when mechanical or chemical methods cannot be used to recycle them. Compostability certification requirements are time-consuming and expensive. Therefore, approaches to accelerate the biodegradation of these polymers in simulated composting conditions can facilitate and speed up the evaluation and selection of potential compostable polymer alternatives and inform faster methods to biodegrade these polymers in real composting. This review highlights recent trends, challenges, and future strategies to accelerate biodegradation by modifying the polymer properties/structure and the compost environment. Both abiotic and biotic methods show potential for accelerating the biodegradation of biodegradable polymers. Abiotic methods, such as the incorporation of additives, reduction of molecular weight, reduction of size and reactive blending, are potentially the most straightforward, providing a level of technology that allows for easy adoption and adaptability. Novel methods, including the concept of self-immolative and triggering the scission of polymer chains in specific conditions, are increasingly sought. In terms of biotic methods, dispersion/encapsulation of enzymes during the processing step, biostimulation of the environment, and bioaugmentation with specific microbial strains during the biodegradation process are promising to accelerate biodegradation.

Biodegradation of Biodegradable Polymers in Mesophilic Aerobic Environments.

Finding alternatives to diminish plastic pollution has become one of the main challenges of modern life. A few alternatives have gained potential for a shift toward a more circular and sustainable relationship with plastics. Biodegradable polymers derived from bio- and fossil-based sources have emerged as one feasible alternative to overcome inconveniences associated with the use and disposal of non-biodegradable polymers. The biodegradation process depends on the environment's factors, microorganisms and associated enzymes, and the polymer properties, resulting in a plethora of parameters that create a complex process whereby biodegradation times and rates can vary immensely. This review aims to provide a background and a comprehensive, systematic, and critical overview of this complex process with a special focus on the mesophilic range. Activity toward depolymerization by extracellular enzymes, biofilm effect on the dynamic of the degradation process, CO2 evolution evaluating the extent of biodegradation, and metabolic pathways are discussed. Remarks and perspectives for potential future research are provided with a focus on the current knowledge gaps if the goal is to minimize the persistence of plastics across environments. Innovative approaches such as the addition of specific compounds to trigger depolymerization under particular conditions, biostimulation, bioaugmentation, and the addition of natural and/or modified enzymes are state-of-the-art methods that need faster development. Furthermore, methods must be connected to standards and techniques that fully track the biodegradation process. More transdisciplinary research within areas of polymer chemistry/processing and microbiology/biochemistry is needed.

Effect of Water-Resistant Properties of Kraft Paper (KP) Using Sulfur Hexafluoride (SF6) Plasma Coating.

Sulfur hexafluoride (SF6) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF6 plasma from 20-300 mTorr of pressure at powers from 25-75 Watts and treatment times from 1-30 min at 13.56 MHz. The prepared papers were characterized by contact angle measurement and water absorption. The selected optimum condition for the plasma-treated KP was 200 mTorr at 50 Watts for 5 min. Advancement with the change in treatment times (3, 5, and 7 min) on the physical and mechanical properties, water resistance, and morphology of KP with SF6 plasma at 200 mTorr and 50 Watts was evaluated. The changes in the chemical compositions of the plasma-treated papers were analyzed with an XPS analysis. The treatment times of 0, 3, 5, and 7 min revealed fluorine/carbon (F/C) atomic concentration percentages at 0.00/72.70, 40.48/40.97, 40.18/37.95, and 45.72/39.48, respectively. The XPS spectra showed three newly raised peaks at 289.7~289.8, 291.5~291.7, and 293.4~293.6 eV in the 3, 5, and 7 min plasma-treated KPs belonging to the CF, CF2, and CF3 moieties. The 5 min plasma-treated paper promoted a better interaction between the SF6 plasma and the paper yielded by the F atoms. As the treatment time for the treated KPs increased, the contact angle, water absorption time, and Cobb test values increased. However, the thickness and tensile strength did not show remarkable changes. The SEM images revealed that, as the treatment time increased, the surface roughness of the plasma-treated KPs also increased, leading to improved water resistance properties. Overall, the SF6 plasma treatment modified the surface at the nano-layer range, creating super-hydrophobicity surfaces.

New opportunities for sustainable bioplastic development: Tailorable polymorphic and three-phase crystallization of stereocomplex polylactide by layered double hydroxide.

Stereocomplexation between enantiomeric poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) is a promising sustainable approach and gaining momentum to overcome the shortcomings of polylactide (PLA) for its use as a replacement for fossil-based plastics. Filler addition in tailoring the crystallization of stereocomplex PLA (SC-PLA) has attracted extensive attention; however, research has primarily focused on the heterogeneous nucleation effect of filler. The impact of filler on the chain behavior of SC-PLA during crystallization has not been exclusively discussed, and the rigid amorphous fraction (RAF) development remains unknown. In this study, the crystallization of PLLA/PDLA blends was modified by low loading of layered double hydroxide (LDH) (≤ 1 wt%) with the proposed local effect of such filler, and additional RAF development was incurred. In the early stage of crystallization, LDH facilitates the pairing of PLLA and PDLA and arrests the ordered SC pairs during the dynamic balance between the separation and pairing of racemic segments. This explains the severely suppressed homochiral (HC) crystallization, promoted SC crystallization, and additional RAF formation driven by the nucleation-induced chain ordering. This work, for the first time, highlights the role of LDH in creating SC-PLA with tailorable polymorphism and RAF, where the mechanism can be extended to other filler-type nucleator systems.

Morphology, Mechanical, and Water Barrier Properties of Carboxymethyl Rice Starch Films: Sodium Hydroxide Effect.

Carboxymethyl rice starch films were prepared from carboxymethyl rice starch (CMSr) treated with sodium hydroxide (NaOH) at 10-50% w/v. The objective of this research was to determine the effect of NaOH concentrations on morphology, mechanical properties, and water barrier properties of the CMSr films. The degree of substitution (DS) and morphology of native rice starch and CMSr powders were examined. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate the chemical structure, crystallinity, and thermal properties of the CMSr films. As the NaOH concentrations increased, the DS of CMSr powders increased, which affected the morphology of CMSr powders; a polyhedral shape of the native rice starch was deformed. In addition, the increase in NaOH concentrations of the synthesis of CMSr resulted in an increase in water solubility, elongation at break, and water vapor permeability (WVP) of CMSr films. On the other hand, the water contact angle, melting temperature, and the tensile strength of the CMSr films decreased with increasing NaOH concentrations. However, the tensile strength of the CMSr films was relatively low. Therefore, such a property needs to be improved and the application of the developed films should be investigated in the future work.

Genome Annotation of Poly(lactic acid) Degrading Pseudomonas aeruginosa, Sphingobacterium sp. and Geobacillus sp.

Pseudomonas aeruginosa and Sphingobacterium sp. are well known for their ability to decontaminate many environmental pollutants while Geobacillus sp. have been exploited for their thermostable enzymes. This study reports the annotation of genomes of P. aeruginosa S3, Sphingobacterium S2 and Geobacillus EC-3 that were isolated from compost, based on their ability to degrade poly(lactic acid), PLA. Draft genomes of the strains were assembled from Illumina reads, annotated and viewed with the aim of gaining insight into the genetic elements involved in degradation of PLA. The draft genome of Sphinogobacterium strain S2 (435 contigs) was estimated at 5,604,691 bp and the draft genome of P. aeruginosa strain S3 (303 contigs) was estimated at 6,631,638 bp. The draft genome of the thermophile Geobacillus strain EC-3 (111 contigs) was estimated at 3,397,712 bp. A total of 5385 (60% with annotation), 6437 (80% with annotation) and 3790 (74% with annotation) protein-coding genes were predicted for strains S2, S3 and EC-3, respectively. Catabolic genes for the biodegradation of xenobiotics, aromatic compounds and lactic acid as well as the genes attributable to the establishment and regulation of biofilm were identified in all three draft genomes. Our results reveal essential genetic elements that facilitate PLA metabolism at mesophilic and thermophilic temperatures in these three isolates.

Effect of Nano-Clay and Surfactant on the Biodegradation of Poly(Lactic Acid) Films.

This study examined the effect of nanoclays and surfactant on the hydrolytic degradation and biodegradation of poly(lactic acid) (PLA) and PLA nanocomposites. Organomodified montmorillonite (OMMT), unmodified montmorillonite (MMT) and an organomodifier (surfactant) for MMT (QAC) were extruded with PLA to produce PLA nanocomposites. The films were produced with the same initial molecular weight, thickness and crystallinity since these properties have a significant effect on the biodegradation process. The biodegradation experiments were carried out in an in-house built direct measurement respirometric system and were evaluated in inoculated vermiculite and vermiculite media for extended periods of time. Hydrolysis experiments were also conducted separately to decouple the abiotic/hydrolysis phase. The results showed no significant variation in the mineralization of PLA nanocomposites as compared to pristine PLA. The addition of nanoclays did not enhance the biodegradability of PLA when the initial parameters were strictly controlled. The hydrolysis test indicated that the nanoclays and surfactant did not aid in the degradation of PLA.

Interaction of nanoclay-reinforced packaging nanocomposites with food simulants and compost environments.

The production of engineered nanomaterials (ENMs) has increased exponentially over the last few decades. ENMs, made from use of engineered nanoparticles (ENPs), have been applied to the food, agriculture, pharmaceutical, and automobile industries. Of particular interest are their applications in packaging nanocomposites for consumer and non-consumer goods. ENPs in nanocomposites are of interest as a packaging material because they reduce the amount of polymer needed, while improving the physical properties. However, the transformation of ENPs in nanocomposite production, their fate, and their toxicity remain unknown while in contact with the package content or after the end of life. The objectives of this chapter are (a) to provide an overview of the main nanoclays used in packaging; (b) to categorize the main polymeric packaging nanocomposites; (c) to provide an overview of the fate and mass transport of ENPs, especially nanoclays; (d) to describe the mass transfer of nanoclays in food simulants and in compost environments; and (e) to identify current and future research needs.

Active Chicken Meat Packaging Based on Polylactide Films and Bimetallic Ag-Cu Nanoparticles and Essential Oil.

Plasticized polylactide (PLA) composite films with multifunctional properties were created by loading bimetallic silver-copper (Ag-Cu) nanoparticles (NPs) and cinnamon essential oil (CEO) into polymer matrix via compression molding technique. Rheological, structural, thermal, barrier, and antimicrobial properties of the produced films, and its utilization in the packaging of chicken meat were investigated. PLA/PEG/Ag-Cu/CEO composites showed a very complex rheological system where both plasticizing and antiplasticizing effects were evident. Thermal properties of plasticized PLA film with polyethylene glycol (PEG) enhanced considerably with the reinforcement of NPs whereas loading of CEO decreased glass transition, melting, and crystallization temperature. The barrier properties of the composite films were reduced with the increase of CEO loading (P < 0.05). Their optical properties were also modified by the addition of both CEO and Ag-Cu NPs. The changes in the molecular organization of PLA composite films were visualized by FTIR spectra. Rough and porous surfaces of the films were evident by scanning electron microscopy. The effectiveness of composite films was tested against Salmonella Typhimurium, Campylobacter jejuni and Listeria monocytogenes inoculated in chicken samples, and it was found that the films loaded with Ag-Cu NPs and 50% CEO showed maximum antibacterial action during 21 days at the refrigerated condition. The produced PLA/Ag-Cu/CEO composite films can be applied to active food packaging. PRACTICAL APPLICATION: The nanoparticles and essential oil loaded PLA composite films are capable of exhibiting antimicrobial effects against Gram (+) and (-) bacteria, and extend the shelf-life of chicken meat. The bionanocomposite films showed the potential to be manufactured commercially because of the thermal stability of the active components during the hot-press compression molding process. The developed bionanocomposites could have practical importance and open a new direction for the active food packaging to control the spoilage and the pathogenic bacteria associated with the fresh chicken meat.

Migration of antioxidants from polylactic acid films: A parameter estimation approach and an overview of the current mass transfer models.

Migration studies of chemicals from contact materials have been widely conducted due to their importance in determining the safety and shelf life of a food product in their packages. The US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) require this safety assessment for food contact materials. So, migration experiments are theoretically designed and experimentally conducted to obtain data that can be used to assess the kinetics of chemical release. In this work, a parameter estimation approach was used to review and to determine the mass transfer partition and diffusion coefficients governing the migration process of eight antioxidants from poly(lactic acid), PLA, based films into water/ethanol solutions at temperatures between 20 and 50°C. Scaled sensitivity coefficients were calculated to assess simultaneously estimation of a number of mass transfer parameters. An optimal experimental design approach was performed to show the importance of properly designing a migration experiment. Additional parameters also provide better insights on migration of the antioxidants. For example, the partition coefficients could be better estimated using data from the early part of the experiment instead at the end. Experiments could be conducted for shorter periods of time saving time and resources. Diffusion coefficients of the eight antioxidants from PLA films were between 0.2 and 19×10-14m2/s at ~40°C. The use of parameter estimation approach provided additional and useful insights about the migration of antioxidants from PLA films.

Migration of antioxidants from polylactic acid films, a parameter estimation approach: Part I - A model including convective mass transfer coefficient.

A two-step solution based on the boundary conditions of Crank's equations for mass transfer in a film was developed. Three driving factors, the diffusion (D), partition (Kp,f) and convective mass transfer coefficients (h), govern the sorption and/or desorption kinetics of migrants from polymer films. These three parameters were simultaneously estimated. They provide in-depth insight into the physics of a migration process. The first step was used to find the combination of D, Kp,f and h that minimized the sums of squared errors (SSE) between the predicted and actual results. In step 2, an ordinary least square (OLS) estimation was performed by using the proposed analytical solution containing D, Kp,f and h. Three selected migration studies of PLA/antioxidant-based films were used to demonstrate the use of this two-step solution. Additional parameter estimation approaches such as sequential and bootstrap were also performed to acquire a better knowledge about the kinetics of migration. The proposed model successfully provided the initial guesses for D, Kp,f and h. The h value was determined without performing a specific experiment for it. By determining h together with D, under or overestimation issues pertaining to a migration process can be avoided since these two parameters are correlated.

Toughening of Poly(lactic acid) and Thermoplastic Cassava Starch Reactive Blends Using Graphene Nanoplatelets.

Poly(lactic acid) (PLA) was reactively blended with thermoplastic cassava starch (TPCS) and functionalized with commercial graphene (GRH) nanoplatelets in a twin-screw extruder, and films were produced by cast-film extrusion. Reactive compatibilization between PLA and TPCS phases was reached by introducing maleic anhydride and a peroxide radical during the reactive blending extrusion process. Films with improved elongation at break and toughness for neat PLA and PLA-g-TPCS reactive blends were obtained by an addition of GRH nanoplatelets. Toughness of the PLA-g-TPCS-GRH was improved by ~900% and ~500% when compared to neat PLA and PLA-g-TPCS, respectively. Crack bridging was established as the primary mechanism responsible for the improvement in the mechanical properties of PLA and PLA-g-TPCS in the presence of the nanofiller due to the high aspect ratio of GRH. Scanning electron microscopy images showed a non-uniform distribution of GRH nanoplatelets in the matrix. Transmittance of the reactive blend films decreased due to the TPCS phase. Values obtained for the reactive blends showed ~20% transmittance. PLA-GRH and PLA-g-TPCS-GRH showed a reduction of the oxygen permeability coefficient with respect to PLA of around 35% and 50%, respectively. Thermal properties, molecular structure, surface roughness, XRD pattern, electrical resistivity, and color of the films were also evaluated. Biobased and compostable reactive blend films of PLA-g-TPCS compounded with GRH nanoplatelets could be suitable for food packaging and agricultural applications.

Impact of Nanoclays on the Biodegradation of Poly(Lactic Acid) Nanocomposites.

Poly(lactic acid) (PLA), a well-known biodegradable and compostable polymer, was used in this study as a model system to determine if the addition of nanoclays affects its biodegradation in simulated composting conditions and whether the nanoclays impact the microbial population in a compost environment. Three different nanoclays were studied due to their different surface characteristics but similar chemistry: organo-modified montmorillonite (OMMT), Halloysite nanotubes (HNT), and Laponite® RD (LRD). Additionally, the organo-modifier of MMT, methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium (QAC), was studied. PLA and PLA bio-nanocomposite (BNC) films were produced, characterized, and used for biodegradation evaluation with an in-house built direct measurement respirometer (DMR) following the analysis of evolved CO2 approach. A biofilm formation essay and scanning electron microscopy were used to evaluate microbial attachment on the surface of PLA and BNCs. The results obtained from four different biodegradation tests with PLA and its BNCs showed a significantly higher mineralization of the films containing nanoclay in comparison to the pristine PLA during the first three to four weeks of testing, mainly attributed to the reduction in the PLA lag time. The effect of the nanoclays on the initial molecular weight during processing played a crucial role in the evolution of CO2. PLA-LRD5 had the greatest microbial attachment on the surface as confirmed by the biofilm test and the SEM micrographs, while PLA-QAC0.4 had the lowest biofilm formation that may be attributed to the inhibitory effect also found during the biodegradation test when the QAC was tested by itself.

Biodegradable Rice Starch/Carboxymethyl Chitosan Films with Added Propolis Extract for Potential Use as Active Food Packaging.

Active films from rice starch/carboxymethyl chitosan (RS/CMCh) incorporated with propolis extract (ppl) were developed and characterized. The effect of the ppl content (0⁻10% w/w based on RS/CMCh) on the developed films' properties were determined by measuring the optical, mechanical, thermal, swelling, barrier, antimicrobial, and antioxidant attributes. The thermal stability and biodegradability of the films were also investigated. As the ppl content increased, free radical scavenging and a* and b* color values increased, whereas luminosity (L*) and swellability of the films decreased. The active films with 5⁻10% ppl possessed antimicrobial ability against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). The active film with 10% ppl displayed increased flexibility and thermal stability, without a change in oxygen permeability. The results indicated that incorporation of ppl into RS/CMCh film could enhance the films' antioxidant and antimicrobial properties.

Preliminary quantification of the permeability, solubility and diffusion coefficients of major aroma compounds present in herbs through various plastic packaging materials.

BACKGROUND: Aroma permeation through packaging material is an important factor when designing a package for food products. The masses of aroma compounds permeating through films over time were measured at 25 °C using a quasi-isostatic system. A model was proposed for estimating the permeability coefficients (P) of key aroma compounds present in fresh herbs (i.e. eucalyptol, estragole, linalool and citral) through major plastic films used by the food industry [i.e. low-density polyethylene (LDPE), polypropylene (PP), nylon (Nylon), polyethylene terephthalate (PET), metalised-polyethylene terephthalate (MPET) and poly(lactic acid) (PLA)]. Solubility coefficients (S) were estimated from the amount of aroma compound sorbed in the films. Diffusion coefficients (D) were estimated following from the relation P = D*S. RESULTS: P and D for all four aroma compounds were highest in LDPE, except for eucalyptol, which P was slightly higher in PLA. The solubility coefficients and contact angles were highest in PLA suggesting the highest affinity of PLA to these aroma compounds. The theoretical solubility parameters were correlated with the solubility coefficients for estragole and citral, but not for eucalyptol and linalool. CONCLUSION: The preliminary P, D and S of eucalyptol, estragole, linalool and citral through LDPE, PP, Nylon, PET, MPET and PLA can be useful in selecting the proper packaging material for preserving these specific aroma compounds in food products and can potentially be used for estimating the shelf life of food products based on aroma loss. © 2017 Society of Chemical Industry.