Low-density Polyethylene Films Research Articles

Field-based assessment of the effect of conventional and biodegradable plastic mulch film on nitrogen partitioning, soil microbial diversity, and maize biomass

In an agricultural context, the use of conventional low-density polyethylene (LDPE) and biodegradable plastic mulch film has been actively promoted, however, the effects on physical and biochemical soil properties, crop growth dynamics, yield, and nutrient cycling of conventional and biodegradable mulch film use in a temperate climate remain largely undetermined. Here, we conducted a field experiment, exploring the effects of no mulch (control), conventional (LDPE), and biodegradable (PLA/PBAT) plastic mulch film on soil and crop (Zea mays L.) nitrogen (N) partitioning after application of 15N-labelled ammonium-nitrate fertiliser. Further, we also investigated the treatment effects on soil physical and biochemical properties (e.g., microbial diversity, compound-specific microbial 15N incorporation, N dynamics), plant development, as well as monitoring the biotic and abiotic degradation of the plastic mulch films. We found that conventional mulch film increased crop yield by 25 % and 15N uptake by 34 % compared to the control, simultaneously reducing 15N retention by 40 % in the topsoil (0–10 cm), but not affecting microbial N use efficiency and N transformation and incorporation into the protein pool. Biodegradable film application resulted in similar biomass (306 ± 14 g plant−1) to both control (275 ± 14 g plant−1) and conventional mulch (344 ± 20 g plant−1) treatments, but significantly reduced 15N crop uptake by 63 % compared to the conventional mulch film. We ascribe this to the accelerated mechanical breakdown and faster degradation of the biodegradable mulch film during the growing season. These findings suggest that current biodegradable plastic mulch film polymer blends may not be a suitable alternative to conventional mulch film in terms of short-term productivity and N use efficiency in a temperate climate for maize production.

Preparation and application of waste cigarette butts-derived mulch film with excellent mechanical properties and optical transparency

Abstract The small waste cigarette butts every year worldwide added up is a significant threat to the environment. The main component of cigarette butts is cellulose acetate, which is an excellent film-forming material. Here, a one-step phase transition method was employed to successfully convert waste cigarette butts into a transparent film. This film (160×18×0.5 mm) derived from waste cigarette butts (CB) has high mechanical strength (fracture stress 23.5 MPa, Young’s modulus 13.1 MPa), good thermal stability, and excellent optical transmittance (91.8%), and low haze (40.3%). Its properties rival those of traditional low-density polyethylene (PE) film. Meanwhile, the CB film displayed fascinating bending-ability and folding resistance. The cigarette butt-derived film with low cost and excellent properties exhibits a promising application as agricultural mulch and provides recycle solution for waste cigarette butts.

Effects of moisture content and packaging on color stability of red pepper (Capsicum annuum L.) powder.

The color stability and quality changes of red pepper powder of various initial moisture content (7%, 10%, and 13%) and packaged with different materials, low-density polyethylene (LDPE) and nylon layered polyethylene (Ny/PE) film pouches or plastic and glass bottles, were compared during storage at 20°C for 126days. In the 7% moisture content sample packaged in LDPE film and plastic bottles, the L* and b*-values increased from 48.2 ± 0.7 and 15.4 ± 1.1 to 65.2-65.9 and 29.5-30.3, respectively, while the a*-value decreased from 26.1 ± 0.7 to 14.2-15.9, indicating a noticeable color change from red to orange. However, the decrease in the capsaicinoid and free sugar content of red pepper powder over time was found to have no significant correlation with moisture content and packaging type. As a result, the color change during the long-term storage of red pepper powder was greatly influenced by the initial moisture content and gas permeability of the packaging material.

Antimicrobial Packaging for Plum Tomatoes Based on ZnO Modified Low-Density Polyethylene.

Food safety and quality are major concerns in the food industry. Despite numerous studies, polyethylene remains one of the most used materials for packaging due to industry reluctance to invest in new technologies and equipment. Therefore, modifications to the current materials are easier to implement than adopting whole new solutions. Antibacterial activity can be induced in low-density polyethylene films only by adding antimicrobial agents. ZnO nanoparticles are well known for their strong antimicrobial activity, coupled with low toxicity and UV shielding capability. These characteristics recommend ZnO for the food industry. By incorporating such safe and dependable antimicrobial agents in the polyethylene matrix, we have obtained composite films able to inhibit microorganisms' growth that can be used as packaging materials. Here we report the obtaining of highly homogenous composite films with up to 5% ZnO by a melt mixing process at 150 °C for 10 min. The composite films present good transparency in the visible domain, permitting consumers to visualize the food, but have good UV barrier properties. The composite films exhibit good antimicrobial and antibiofilm activity from the lowest ZnO composition (1%), against both Gram-positive and Gram-negative bacterial strains. The homogenous dispersion of ZnO nanoparticles into the polyethylene matrix was assessed by Fourier transform infrared microscopy and scanning electron microscopy. The optimal mechanical barrier properties were obtained for composition with 3% ZnO. The thermal analysis indicates that the addition of ZnO nanoparticles has increased thermal stability by more than 100 °C. The UV-Vis spectra indicate a low transmittance in the UV domain, lower than 5%, making the films suitable for blocking photo-oxidation processes. The obtained films proved to be efficient packaging films, successfully preserving plum (Rome) tomatoes for up to 14 days.

Comparison of the Effects of LDPE and PBAT Film Residues on Soil Microbial Ecology.

The plastic film is extensively applied with limited recycling, leading to the long-run residue accumulation in soil, which offers a distinctive habitat for microorganisms, and creates a plastisphere. In this study, traditional low-density polyethylene (LDPE) plastic film and biodegradable polybutylene adipate terephthalate (PBAT) plastic film materials were selected to test their effects on soil microbial ecology. Based on high-throughput sequencing, compared to the soil environment, the alpha-diversity of bacterial communities in plastisphere was lower, and the abundance of Actinobacteria increased. Plastic film residues, as bacterial habitats, exhibited greater heterogeneity and harbor unique bacterial communities. The communities were distinguished between plastisphere and soil environment by means of a random-forest (RF) machine-learning model. Prominent distinctions emerged among bacterial functions between soil environment and plastisphere, especially regarding organics degradation. The neutral model and null model indicated that the constitution of bacterial communities was dominated by random processes except in LDPE plastisphere. The bacterial co-occurrence network of the plastisphere exhibited higher complexity and modularity. This study contributes to our comprehending of characteristics of plastisphere bacterial communities in soil environment and the associated ecological risks of plastic film residues accumulation.

Biodegradation of low-density polyethylene film by two bacteria isolated from plastic debris in coastal beach

Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film's surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.

Plastic Litter Emits the Foraging Infochemical Dimethyl Sulfide after Submersion in Freshwater Rivers.

Plastic pollution is widespread throughout aquatic environments globally, with many organisms known to interact with and ingest plastic. In marine environments, microbial biofilms that form on plastic surfaces can produce the odorous compound dimethyl sulfide (DMS), which is a known foraging cue. This has been shown to increase the ingestion of plastic by some invertebrates and therefore act as a biological factor which influences the risks of plastic to marine ecosystems. In freshwater however, the production of DMS has been largely overlooked, despite the known sensitivity of some freshwater species to this compound. To address this gap, the present study analyzed the production of DMS by biofilms which formed on low-density polyethylene and polylactic acid films after 3 and 6 weeks of submersion in either a rural or an urban United Kingdom river. Using gas chromatography-mass spectrometry, the production of DMS by these biofilms was consistently identified. The amount of DMS produced varied significantly across river locations and materials, with surfaces in the urban river generally producing a stronger signal and plastics producing up to seven times more DMS than glass control surfaces. Analysis of biofilm weight and photosynthetic pigment content indicated differences in biofilm composition across conditions and suggested that DMS production was largely driven by nonphotosynthetic taxa. For the first time this work has documented the production of DMS by plastic litter after submersion in freshwater rivers. Further work is now needed to determine if, as seen in marine systems, this production of DMS can encourage the interaction of freshwater organisms with plastic litter and therefore operate as a biological risk factor in the impacts of plastic on freshwater environments. Environ Toxicol Chem 2024;43:1485-1496. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Development of Antifungal Packaging From Low‐Density Polyethylene With Essential Oil of Oregano and Potassium Sorbate

ABSTRACTAntimicrobial low‐density polyethylene (LDPE) films were developed by adding 0%, 0.5%, 1.0%, 2.5% and 5.0% (w/w) of Mexican oregano essential oil (OEO) or potassium sorbate (PS) as a positive antifungal control to inhibit the growth of Penicillium expansum, Penicillium citrinum and Aspergillus niger in vitro. Three methods of adding OEO in LDPE were evaluated; the best OEO yield in film was achieved when OEO was incorporated after laminating (88%); otherwise, when added into cool‐melting resin, OEO lost up to 91.5% from LDPE and completely volatilized (>99%) when combined with the resin before melting. PS yields in LDPE film were > 88% when incorporated into cool‐melted resin. Antimicrobial films with 2.5% or 5.0% (w/w) OEO or PS delayed the growth of P. expansum and P. citrinum for up to 4–5 days, and for A. niger, only films with 5.0% of OEO retarded its growth for 5 days. The modified Gompertz model was used to describe mould growth response, obtaining the parameters A (maximum growth), μm (maximum growth rate) and λ (lag phase), which correctly fit the data. P. citrinum was the most sensitive mould, and A. niger was the most resistant to the tested antimicrobials. The addition of antimicrobial agents significantly (p < 0.05) impacted the physical and mechanical properties of the LDPE films, wherein thickness and puncture strength were increased, and the colour changed (reducing the transparency and promoting the yellowness). In contrast, the water vapour transmission rate was dropped only by incorporating PS.

Visible-light driven photodegradation of low-density polyethylene (LDPE) using BiOCl–ZrO2 nanocomposite: A sustainable strategy for mitigating plastic pollution

This study aims to reduce plastic pollution by decomposing low-density polyethylene (LDPE) through an environmentally friendly approach using a novel BiOCl–ZrO2 nanocomposite under visible-light irradiation at room temperature. Visible-light irradiation is a form of clean energy, so we explored the feasibility and prospective solution for plastic waste mitigation by utilizing visible-light to attain sustainable development goal 7 (SDG 7). To fabricate photodegradable LDPE, it was blended with BiOCl nanoparticles (NPs) and its nanocomposite (BiOCl–ZrO2) separately via a facile solution casting method. The fabricated samples were assessed for the degradation of LDPE before and after 24 days of visible-light irradiation at room temperature. The prepared nanocomposites were thoroughly characterized by different analytical techniques, including XRD, FT–IR, XPS, FE–SEM, TGA, BET and UV–Vis DRS. The successful photodegradation of low-density polyethylene (LDPE) using a BiOCl–ZrO2 nanocomposite is supported by the presence of a higher carbonyl index, as evidenced by FT–IR analysis. The field-emission scanning electron microscopy (FE–SEM) analysis unveiled numerous perforations and prominent coarse morphological attributes, suggesting significant decomposition and disintegration of the LDPE film across the active surface sites of BiOCl–ZrO2. The weight reduction of LDPE@BiOCl–ZrO2 (600 ˚C) (10 wt%) composite film reached 48.67% under visible-light irradiation for 24 days at room temperature. The degradation rate exhibited significant sensitivity to variations in the concentration of the BiOCl–ZrO2 nanocomposite within the LDPE film. Investigation of the photodegradation mechanism suggested the formation of a type–II heterojunction–based photocatalytic system. The relatively low bandgap energy of ZrO2 (3.1 eV), facilitates the rapid migration of conduction band electrons to the conduction band of BiOCl. This migration process is facilitated by the favourable energy level alignment between the conduction bands of ZrO2 and BiOCl, enabling efficient electron transfer between the two materials. The large band gap of BiOCl (3.56 eV) permits the movement of valence band holes to the ZrO2 valance band. The spontaneous circulation of charge carriers within the heterostructure crystal maintains the charge separation and defers the recombination rate for an extended period. The photodegraded LDPE fragments are biodegradable and help to reduce plastic pollution. The environmental friendliness of the BiOCl–ZrO2 nanocomposite-assisted plastic waste remediation process was investigated using carbon footprint measurement. A tentative estimation suggested that the remediation process of 100 Kg of plastic waste may contribute to around 0.133 tons of carbon footprint.

Manufacturing process and annealing influence on the dynamic mechanical properties and physical structure of LLDPE thin films

Thin films of Linear Low-Density Polyethylene are used for stratospheric balloon applications. They undergo tensile mechanical stress on a wide range of temperatures [-95; 55]°C. The aim of this study is to compare the influence of blown film and double-bubble manufacturing processes on the crystalline phase and mechanical properties of the films through their operating temperatures (flight, storage, and transportation temperatures). Dynamic Mechanical Analysis and Differential Scanning Calorimetry have been used to monitor the dynamic mechanical properties in tension mode and the crystalline phase of the films respectively. The films mechanical properties are dependent on their manufacturing process. The double-bubble process allows isotropic tensile mechanical properties regarding stretching direction, whereas the blown film process favors only transversal direction. To simulate different storage conditions, annealing has been performed. The influence of annealing on the tensile mechanical properties of the films depends mainly on the internal stress stored during manufacturing. The double-bubble process produces a biaxially stretched film with a higher stretching ratio than blown films. The dissipated internal stress can be associated with thermal shrinkage and goes up to 10 % for the biaxially stretched film. The more internal stress is stored, the more E′ and E″ increases. Annealing also favors the formation of a secondary crystalline phase that is dependent on annealing temperature and time, and exhibits αc relaxation. After annealing, the amorphous phase is less stretched, and the crystalline phase keeps its orientation.

Thin, disposable, antibacterial, heat-pressed photocatalytic plastic films

The production of several different thin, highly flexible, disposable, antibacterial, photocatalytic plastic films is described. A thin layer of a semiconductor photocatalyst, SC, powder is partially embedded in a thin (ca. 30 μm), highly flexible film of low-density polyethylene, LDPE, by heat-pressing the two together. The resulting SC/LDPE film is then tested for photocatalytic activity, via the photo-oxidised bleaching of methylene blue, MB, and photocatalysed antibacterial activity, via its inactivation of Escherichia coli, E. coli. The SCs tested include, P25 TiO2, high surface area Tronox rutile TiO2, low surface area rutile TiO2, ZnO and WO3. The MB test results reveal photocatalytic activities of the SC/LDPE films are, P25 TiO2 > ZnO > rutile TiO2 ≈ Tronox rutile TiO2 > WO3, which suggest the kinetics depend largely on the redox potential of the photogenerated conductance band electrons. In contrast, the E. coli deactivation results show that the order of activities of the SC/LDPE films, in the dark and (with an increased rate) upon illumination, are, Tronox rutile TiO2 > P25 TiO2 > ZnO > WO3 > rutile TiO2, which is similar to the variation in roughness factor, Rf. It appears that rough films are better at deactivating E. coli, not only under illumination, via both a photocatalytic and thermal mechanism, but also in the dark, via a ‘bed-of-nails’/shear stress physical mechanism. Encouragingly, in most cases, the photocatalysed antibacterial activity exhibited by the SC/LDPE films is not much (ca. 74 %) lower when a cool white fluorescent rather than UVA lamp is used (UVA irradiance = 47 μW/cm2 and 1.5 mW/cm2, respectively). The Tronox rutile TiO2 film was also found to be effective in deactivating another Gram-negative bacterium and, to a lesser extent, two Gram-positive bacterial species. The potential of these thin plastic films with a notable antibacterial activity under room light and in the dark is discussed briefly.

Biodegradation of low-density polyethylene film by Bacillus gaemokensis strain SSR01 isolated from the guts of earthworm.

In recent years, low-density polyethylene (LDPE) has emerged as an essential component of the routine tasks that people engage in on a daily basis. However, over use of it resulted in environmental buildup that contaminated aquatic habitats and human health. Biodegradation is the most effective way for controlling pollution caused by synthetic plastic waste in a sustainable manner. In the present study, the LDPE degrading bacterial strain was screened from gut of Earthworms collected from plastic waste dumped area Mettur dam, Salem district, Tamil Nadu, India. The LDPE degrading bacterial strain was screened and identified genotypically. The LDPE degrading Bacillus gaemokensis strain SSR01 was submitted in NCBI. The B. gaemokensis strain SSR01 bacterial isolate degraded LDPE film after 14days of incubation and demonstrated maximum weight loss of up to 4.98%. The study of deteriorated film using attenuated total reflection-Fourier transform infrared revealed the presence of a degraded product. The degradation of LDPE film by B. gaemokensis strain SSR01 was characterized by field-emission scanning electron microscopy analysis for surface alterations. The energy dispersive X-ray spectroscopy test confirmed that the broken-down LDPE film had basic carbon reduction. The present study of LDPE flim biodegradation by B. gaemokensis strain SSR01 has acted as a suitable candidate and will help in decreasing plastic waste.

Exploring the potential of earthworm gut bacteria for plastic degradation

The use of plastic mulch films in agriculture leads to the inevitable accumulation of plastic debris in soils. Here, we explored the potential of earthworm gut-inhabiting bacterial strains (Mycobacterium vanbaalenii (MV), Rhodococcus jostii (RJ), Streptomyces fulvissimus (SF), Bacillus simplex (BS), and Sporosarcina globispora (SG) to degrade plastic films (⌀ = 15 mm) made from commonly used polymers: low-density polyethylene film (LDPE-f), polylactic acid (PLA-f), polybutylene adipate terephthalate film (PBAT-f), and a commercial biodegradable mulch film, Bionov-B® (composed of Mater-Bi, a feedstock with PBAT, PLA and other chemical compounds). A 180-day experiment was conducted at room temperature (x̄ =19.4 °C) for different strain–plastic combinations under a low carbon media (0.1× tryptic soy broth). Results showed that the tested strain–plastic combinations did not facilitate the degradation of LDPE-f (treated with RJ and SF), PBAT-f (treated with BS and SG), and Bionov-B (treated with BS, MV, and SG). However, incubating PLA-f with SF triggered a reduction in the molecular weights and an increase in crystallinity. Therefore, we used PLA-f as model plastic to study the influence of temperature (“room temperature” & “30 °C”), carbon source (“carbon-free” & “low carbon supply”), and strain interactions (“single strains” & “strain mixtures”) on PLA degradation. SF and SF + RJ treatments significantly fostered PLA degradation under 30 °C in a low-carbon media. PLA-f did not show any degradation in carbon-free media treatments. The competition between different strains in the same system likely hindered the performance of PLA-degrading strains. A positive correlation between the final pH of culture media and PLA-f weight loss was observed, which might reflect the pH-dependent hydrolysis mechanism of PLA. Our results situate SF and its co-culture with RJ strains as possible accelerators of PLA degradation in temperatures below PLA glass transition temperature (Tg). Further studies are needed to test the bioremediation feasibility in soils.

Isolation of Plastic Degrading Fungi from Plastic Dumped Sites

Plastics that are biodegradable can be considered environment friendly, they have an increasing range of potential application and are driven by the growing use of plastics in packaging. In this study, the biodegradation of Low-density Polyethylene films was analyzed about 1 month of incubation in liquid culture method. In this investigation, soil samples were collected from two different plastic dumped sites and the fungus were isolated through spread plate technique from diluted soil samples. Among the six fungal isolates were tested for checking its degradation ability of plastics. This study showed the cultural analysis for its ability to adhere and grow on the LDPE films. The activity enzyme produced by these fungal isolates was responsible for the biodegradation. Isolating plastic-degrading fungi from plastic dumped sites serves several important purposes, Understanding the role of fungi in plastic degradation can shed light on the ecological impact of plastic pollution on ecosystems. It can also help identify potential solutions to mitigate this impact. Isolating fungi from plastic dumped sites contributes to the exploration of microbial biodiversity in these environments. It can lead to the discovery of novel fungal species with unique abilities to degrade plastic.

Synthesis of two TiO2-based prodegradant additives and their efficiency in inducing the accelerated photo-oxidation of low-density polyethylene

In this study, two prodegradant additives derived from TiO2 nanoparticles were synthesized and comprehensively characterized through a range of analytic techniques, such as X-ray diffraction (DRX), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The hydroxyl groups adsorbed on the surface of TiO2 were esterified with biobased arachidonic acid (AA) and cervonic acid (DHA), resulting in levels of functionalization at 13 % and 16 % w/w, respectively. These additives were incorporated into low-density polyethylene (LDPE) films, at concentrations of 1 % and 3 % w/w. The prodegradant efficiency of the additives was subsequently assessed through accelerated UV aging. Following 200 h of exposure, the aged films experienced a loss in molecular weight (Mw) by approximately 95 %, accompanied by carbonyl indexes (CI) measuring 1.8 and 2.0. This high level of degradation observed in the LDPE films denotes an effective degradation mechanism, reliant on the generation of hydroxyl radicals by the TiO2 moiety, upon UV light exposure, and the subsequent abstraction of labile hydrogens within the polyunsaturated sidechain of the additives, resulting in the formation of peroxyl radicals, thereby initiating the swift auto-oxidation of the polyethylene films.

Biogenic silver nanoparticle-coated low density polyethylene film with antibacterial and antioxidant properties

Biogenic silver nanoparticle-coated low density polyethylene film with antibacterial and antioxidant properties

Microbial degradation of low-density polyethylene (LDPE) and polystyrene using Bacillus cereus (OR268710) isolated from plastic-polluted tropical coastal environment

The study focused on marine bacteria, specifically Bacillus cereus, sourced from heavily polluted coastal areas in Tamil Nadu, aiming to assess their efficacy in degrading low-density polyethylene (LDPE) and polystyrene over a 42-day period. When LDPE and polystyrene films were incubated with Bacillus cereus, they exhibited maximum weight losses of 4.13 ± 0.81 % and 14.13 ± 2.41 %, respectively. Notably, polystyrene exhibited a higher reduction rate (0.0036 day−1) and a shorter half-life (195.29 days). SEM images of the treated LDPE and polystyrene unveiled surface erosion with cracks. The energy dispersive X-ray (EDX) analysis revealed elevated carbon content and the presence of oxygen in the treated LDPE and polystyrene films. The ATR-FTIR spectra exhibited distinctive peaks corresponding to functional groups, with observable peak shifts in the treated films. Notable increases were detected in carbonyl, internal double bond, and vinyl indices across all treated groups. Additionally, both treated LDPE and polystyrene showed reduced crystallinity. This research sheds light on Bacillus cereus (OR268710) biodegradation capabilities, emphasizing its potential for eco-friendly waste management in coastal regions.

Effect of perforated low-density polyethylene films on postharvest quality of avocado fruit

Avocado (Persea americana Mill.) being a climacteric fruit, is very prone to quality deterioration and spoilage due to high metabolic activities which leads to postharvest and economic losses. The purpose of this study was to evaluate the impact of perforated low-density polyethylene (LDPE) packaging films on postharvest quality and shelf life of ‘Fuerte’ avocado. Fruit were packaged in LDPE plastics (20 and 40 μm) whereas unpackaged fruit were considered as control. Fruit were kept at ambient environments (21 ± 1 °C and 60.0 ± 5% RH) for 12 days and sampled at 4 days interval. The in-pack avocado created a suitable headspace with low O2 and high CO2 concentrations, which yielded improved preservation of postharvest quality and prolonged shelf life of the avocado. Fruit packed in both 20 and 40 μm LDPE films had lower ethylene production and respiration rates, weight loss, firmness loss, preserved fruit size, high pH, titratable acidity, low soluble solid content, sugar:acid ratio, malondialdehyde content and lipoxygenase activity compared to control. Fruit in LDPE films had no symptoms of decay (20 μm) and slight incidence and decay (40 μm) and were markable during shelf life compared to control fruit had severe decay symptoms and were unmarkable at the end of shelf life. These findings indicated that LDPE films were effective in preserving postharvest quality and extending shelf life of avocado fruit.

Biofilms on plastic litter in an urban river: Community composition and activity vary by substrate type.

In aquatic ecosystems, plastic litter is a substrate for biofilms. Biofilms on plastic and natural surfaces share similar composition and activity, with some differences due to factors such as porosity. In freshwaters, most studies have examined biofilms on benthic substrates, while little research has compared the activity and composition of biofilms on buoyant plastic and natural surfaces. Additionally, the influence of substrate size and successional stage on biofilm composition has not been commonly assessed. We incubated three plastics of distinct textures that are buoyant in rivers, low-density polyethylene (rigid; 1.7 mm thick), low-density polyethylene film (flexible; 0.0254 mm thick), and foamed polystyrene (brittle; 6.5 mm thick), as well as wood substrates (untreated oak veneer; 0.6 mm thick) in the Chicago River. Each material was incubated at three sizes (1, 7.5, and 15 cm2 ). Substrates were incubated at 2-10 cm depths and removed weekly for 6 weeks. On each substrate we measured chlorophyll concentration, biofilm biomass, respiration, and flux of nitrogen gas. We sequenced 16S and 23S rRNA genes at Weeks 1, 3, and 6 to capture biofilm community composition across successional stages. Chlorophyll, biomass, and N2 flux were similar across substrates, but respiration was greater on wood than plastics. Bacterial and algal richness and diversity were highest on foam and wood compared to polyethylene substrates. Bacterial biofilm community composition was distinct between wood and plastic substrates, while the algal community was distinct on wood and foam, which were different from each other and polyethylene substrates. These results indicate that polymer properties influence biofilm alpha and beta diversity, which may affect transport and distribution of plastic pollution and associated microbes, as well as biogeochemical processes in urban rivers. This study provides valuable insights into the effects of substrate on biofilm characteristics, and the ecological impacts of plastic pollution on urban rivers. PRACTITIONER POINTS: Plastic physical and chemical properties act as forces of selection for biofilm. Biofilm activity was similar among three different types of plastic. Community composition between plastic and wood was different.

Study of coating effectiveness of grape fruit seed extract incorporated Chitosan/cornstarch based active packaging film on grapes

The aim of the present study was to optimize the manufacturing process of grapefruit seed extract (GFSE) incorporated Chitosan (0.75 %, 2 % w/w) and various corn starch concentration of CHCS film of ratio 2:1, 1:1, 1:2 respectively using sorbitol as plasticizer. Optimization of chitosan concentration in chitosan corn starch film was done on the basis of physicochemical properties e.g. moisture content, film thickness, solubility, water vapour permeability and characterization of the films were done. It was reported that the films with CH: CS ratio 2:1 had tensile strength values comparable to that of other films with CH: CS ratio 1:1 and 1:2. Hence, films with 2 % (w/w) chitosan and CH: CS ratio 2:1 was found best among all the film samples shelf life extended to 20 days. GFSE incorporated film was found to have better anti-microbial properties as compared to commercial polypropylene (PP) and low density polyethylene (LDPE) films. GFSE incorporated CHCS film of ratio 2:1 was applied on Grape fruits. The antimicrobial effect of coating formulation on grape was mathematically calculated by predictive kinetic models and digital imaging. Sensory evaluation of applied coating formulation was found very efficient and confirmed the shelf life enhancement of 20 days.