Ammonia-responsive chitosan/polymethacrylamide double network hydrogels with high-stretchability, fatigue resistance and anti-freezing for real-time chicken breast spoilage monitoring.

Hydrogels are a promising option for detecting food spoilage in humid conditions, but current indicators are prone to mechanical flaws, posing a concern for packaging systems that require strong mechanical properties. Herein, a double network hydrogel was prepared by polymerizing methacrylamide in a chitosan system with aluminum chloride and glycerol. The resulting hydrogel demonstrated high stretchability (strain >1500 %), notch insensitivity, excellent fatigue resistance, and exceptional anti-freezing capabilities even at -21 °C. When incorporating bromothymol blue (BB) or methyl red (MR), or mixtures of these dyes into the hydrogels as indicators, they exhibited sensitive colorimetric responses to pH and NH3 levels at different temperatures. Hydrogels immobilizing BB to MR ratios of 1:1 and 1:2 displayed clearer and more sensitive color responses when packed into chicken breast, with a sensitivity level of 1.5 ppm of total volatile basic nitrogen (TVB-N). This color response correlated positively with the accumulation of TVB-N on the packaging during storage at both 25 °C and 4 °C, providing sensitive indications of chicken breast deterioration. Overall, the developed hydrogels and indicators demonstrate enhanced performance characteristics, including excellent mechanical strength and highly NH3-sensitive color responses, making significant contributions to the food spoilage detection and intelligent packaging systems field.

Adopting the "Missile boats-Aircraft carrier" strategy via human-contact friendly oxidized starch to achieve rapid-sustainably antibacterial paperboards.

Polysaccharide-based antibacterial agents have received tremendous attention for the facile fabrication, low toxicity, and high compatibility with carbohydrate polymers. However, the antimicrobial mechanism, activity, and cytotoxicity for human-contact paperboards of oxidized starch (OST) with high carboxyl content, has not been explored. Herein, OST-27- 75 with 27- 75 wt% carboxyl contents were fabricated by H2O2 and coated on paperboards. Strikingly, OST-55 coating layer (16 g/m2) did not exfoliate from paperboard and possessed the rapid-sustainable antibacterial performance against Staphylococcus aureus and Escherichia coli. The soluble and insoluble components of OST-55 (OST55-S: OST55-IS mass ratio = 1: 2.1) presented different antimicrobial features and herein they were characterized by GC-MS, FT-IR, H-NMR, XRD, bacteriostatic activities, biofilm formation inhibition and intracellular constituent leakage to survey the antibacterial mechanism. The results revealed OST55-S displayed an amorphous structure and possessed superior antibacterial activity against S. aureus (MIC = 4 mg/mL) and E. coli (MIC = 8 mg/mL). Distinctively, OST55-S could rapidly ionize [H+] like "missile boats" from small molecule saccharides, while OST55-IS polyelectrolyte could continuously and slowly release for [H+] like an "aircraft carrier" to inhibit biofilm formation and disrupt cell structure. Eventually, the "Missile boats-Aircraft carrier" strategy provided a green methodology to fabricate polymeric antibacterial agents and expanded the use of cellulose-based materials.

Extrusion-blown oxidized starch/poly(butylene adipate-co-terephthalate) biodegradable active films with adequate material properties and antimicrobial activities for chilled pork preservation.

Food safety concerns from spoilage and non-degradable packaging risk human health. Progress made in biodegradable plastic films, but limited study on biomass composite films with favorable morphological, mechanical, and inherent antibacterial properties for fresh meat preservation. Herein, we present a versatile packaging film created through the extrusion blowing process, combining oxidized starch (OST) with poly(butylene adipate-co-terephthalate) (PBAT). SEM analysis revealed even distribution of spherical OST particles on film's surface. FTIR spectra revealed new intermolecular hydrogen bonds between OST and PBAT. While combining OST slightly reduced tensile properties, all composite films met the required strength of 16.5 ± 1.39 MPa. Notably, films with 40 % OST showed over 98 % antibacterial rate against Staphylococcus aureus within 2 h. pH wasn't the main cause of bacterial growth inhibition; OST hindered growth by interfering with nutrient absorption and metabolism due to its carboxyl groups. Additionally, OST disrupted bacterial membrane integrity and cytoplasmic membrane potential. Remarkably, the OST/PBAT film excellently preserved chilled fresh pork, maintaining TVB-N level at 12.6 mg/100 g on day 6, microbial count at 105 CFU/g within 6-10 days, and sensory properties for 8 days. It extended pork's shelf life by two days compared to polyethylene film, suggesting an alternative to a synthetic material.

Sugarcane Pulp Take-Out Containers Produce More Microparticles in Acidic Foods.

In the current study, the production of microparticles released from fifteen commercial sugarcane pulp (SCP) take-out containers into different food simulants under different conditions was investigated, where deionized water (DI water), 4% acetic acid (4% HAc), and 95% ethanol (95% EtOH) were used to simulate aqueous, acidic, and fatty foods, respectively. Results showed that compared with DI water and 95% EtOH, 4% HAc caused the degradation of sugarcane fibers, thereby releasing the highest number of microparticles. The overall migration values of the sugarcane pulp take-out containers in 4% HAc were above the prescribed limit of 10 mg/dm2. Furthermore, it was estimated that consumers may intake 36,400-231,700 microparticles in a take-out container at one time, of which the proportion of particles with a particle size between 10 and 500 µm was the highest, ranging from 26,470 to 216,060 items. Moreover, the Al and Fe are the main metals in these take-out containers, ranging between 35.16 and 1244.04 and 44.71 and 398.52 mg/kg, respectively, followed by Pb, Ti, and Sr. This study provides important information that the safety of both the production of microparticles and the metallic elements should be considered for SCP take-out containers when in contact with food.

Effect of neutralization treatment on properties of chitosan/bamboo leaf flavonoids/nano-metal oxide composite films and application of films in antioxidation of rapeseed oil.

Neutralization treatment improved the slow-release antioxidant food packaging function of chitosan (CS)/bamboo leaf flavone (BLF)/nano-metal oxides composite films. The film cast from the CS composite solution neutralized by KOH solution had good thermal stability. The elongation at break of the neutralized CS/BLF film was increased by about 5 times, which provided the possibility for its packaging application. After 24 h of soaking in different pH solutions, the unneutralized films swelled severely and even dissolved, while the neutralized films maintained the basic structure with a small degree of swelling, and the release trend of BLF conformed to the logistic function (R2 ≥ 0.9186). The films had a good ability to resist free radicals, which was related to the release amount of BLF and the pH of the solution. The antimicrobial neutralized CS/BLF/nano-ZnO film, like the nano-CuO and Fe3O4 films, were effective in inhibiting the increase in peroxide value and 2-thiobarbituric acid induced by thermal oxygen oxidation of rapeseed oil and had no toxicity to normal human gastric epithelial cells. Therefore, the neutralized CS/BLF/nano-ZnO film is likely to become an active food packaging material for oil-packed food, which can prolong the shelf life of packaged food.

Progress in research on the safety of silicone rubber products in food processing.

Silicone rubber (SR) is widely used in the food processing industry due to its excellent physical and chemical properties. However, due to the differences in SR product production formulas and processes, the quality of commercially available SR products varies greatly, with chemical and biological hazard potentials. Residual chemicals in SR, such as siloxane oligomers and 2,4-dichlorobenzoic acid, are non-intentionally added substances, which may migrate into food during processing so the safe use of SR must be guaranteed. Simultaneously, SR in contact with food is susceptible to pathogenic bacteria growing and biofilm formation, like Cronobacter sakazakii, Staphylococcus aureus, Salmonella enteritidis, and Listeria monocytogenes, posing a food safety risk. Under severe usage scenarios such as high-temperature, high-pressure, microwave, and freezing environments with long-term use, SR products are more prone to aging, and their degradation products may pose potential food safety hazards. Based on the goal of ensuring food quality and safety to the greatest extent possible, this review suggests that enterprises need to prepare high-quality food-contact SR products by optimizing the manufacturing formula and production process, and developing products with antibacterial and antiaging properties. The government departments should establish quality standards for food-contact SR products and conduct effective supervision. Besides, the reusable SR products should be cleaned by consumers immediately after use, and the deteriorated products should be replaced as soon as possible.

Stretch-Induced Robust Intrinsic Antibacterial Thermoplastic Gelatin Organohydrogel for a Thermoenhanced Supercapacitor and Mono-gauge-factor Sensor.

Sustainable organohydrogel electronics have shown promise in resolving the electronic waste (e-waste) evoked by traditional chemical cross-linking hydrogels. Herein, thermoplastic-recycled gelatin/oxidized starch (OST)/glycerol/ZnCl2 organohydrogels (GOGZs) were fabricated by introducing the anionic polyelectrolyte OST and solvent exchange strategy to construct noncovalently cross-linking networks. Benefiting from the electrostatic interaction and hydrogen and coordination bonds, GOGZ possessed triple-supramolecular interactions and a continuous ion transport pathway, which resulted in excellent thermoplasticity and high ionic conductivities and mechanical and antibacterial properties. Because of the thermally induced phase transition of gelatin, GOGZ exhibited isotropic-ionic conductivity with a positive temperature coefficient and realized intrinsic affinity with the activated carbon electrode for fabricating a double-layer structure supercapacitor. These novel features significantly decreased the impedance (3.71 Ω) and facilitated the flexible supercapacitors to achieve thermoenhanced performance with 4.89 Wh kg-1 energy density and 49.2 F g-1 specific mass capacitance at 65 °C. Fantastically, the GOGZ-based stress sensor exhibited a monolinear gauge factor (R2 = 0.999) at its full-range strain (0 to 350%), and its sensitivity increased with the thermoplastic-recycled times. Consequently, this sustainable and temperature-sensitive sensor (-40 to 60 °C) could serve as health monitoring wearable devices with excellent reliability (R2 = 0.999) at tiny strain. Moreover, GOGZ could achieve efficient self-enhancement by stretch-induced alignment. The sustained weighted load, tensile strength, and elongation at break of the stretch-induced GOGZ were 6 kg/g, 2.37 MPa, and 300%, respectively. This self-enhanced feature indicated that GOGZ can be utilized as an artificial muscle. Eventually, GOGZ obtained high intrinsic antibiosis (Dinhibition circle > 25 mm) by a binding species (-COO-NH3+-) from COOH in OST and NH2 in gelatin, freezing resistance, and water retention. In summary, this study provided an effective strategy to fabricate thermoplastic-recycled organohydrogels for multifunctional sustainable electronics with novel performance.

Chemical contaminants from food contact materials and articles made from or containing wood and bamboo - a review.

Due to recently introduced 'so-called' bio- and plant-based friendly food contact materials and articles (FCM/FCA), some neglected safety issues need to be raised. In this review, potential chemical contaminants from FCM/FCA made from or containing wood and bamboo are presented. Sources, migration, and analytical issues in determining contaminants including intentionally and non-intentionally added substances (IAS and NIAS, respectively) are reviewed. Most of the contaminants are components from melamine-formaldehyde-resin (MFR), paints and coatings, preservatives, and bleaching agents. Tableware made of MFR containing bamboo fibres as a filler are not always suitable for use as tableware since harmful amounts of melamine and formaldehyde can migrate from the tableware into food and even accelerate the degradation of certain polymers with which they are mixed. In addition, in the EU bamboo in plastic FCM is not authorized under Regulation (EU) 10/2011. Paints and coatings used to provide surface coverage for bamboo and wooden articles also pose a risk of migration of heavy metals. Limits on preservatives in wood FCM are covered by legislation in many countries, nevertheless their contamination should not be ignored. Some wood species are considered 'toxic' or contain 'toxic' constituents that should not be used in contact with food, which are worth considering for legislation. IAS analyses in bamboo and wooden FCM is generally not a problem, but has proven to be more challenging for NIAS. Due to a complex mixture of substances contained in plant-based materials, there is a need to improve databases for non-target screening of such chemicals.

The clinical efficacy and safety of equipment-assisted intravesical instillation of mitomycin C after transurethral resection of bladder tumour in patients with nonmuscular invasive bladder cancer: A meta-analysis.

BACKGROUND: This review and meta-analysis aimed to systematically evaluate the clinical efficacy and safety of equipment-assisted intravesical instillation of mitomycin C (MMC) in patients with nonmuscular invasive bladder cancer (NMIBC) after transurethral resection of bladder tumour (TURBT). METHODS: The Embase, PubMed, CNKI, CBM, WANGFANG, VIP, Cochrane Library, and Clinicaltrial.com databases were searched for articles published before April 2022. The experimental group was treated with intravesical instillation of MMC assisted by equipment, including radiofrequency-induced thermochemotherapy, conductive thermochemical therapy, electromotive drug administration, or locoregional hyperthermia. The control group was treated with simple MMC perfusion. The outcomes of interest in the meta-analysis were recurrence, progression, side-effects, gross haematuria, and bladder irritation. RESULTS: A total of 15 studies that enrolled 1,190 patients were included in the meta-analysis. Compared to that of the control group, device-assisted intravesical instillation of MMC significantly reduced both tumour recurrence (odds ratio [OR] = 0.32, 95% confidence interval [CI] [0.24, 0.42], P <0.00001) and progression (OR = 0.29, 95% CI [0.12, 0.67], P = 0.004). There were no significant differences between the two groups in terms of safety (OR = 1.21, 95% CI [0.66,2.21], P = 0.54), bladder irritation (OR = 1.06, 95% CI [0.72,1.55], P = 0.78), or gross haematuria (OR = 1.11, 95% CI [0.64,1.94], P = 0.72). CONCLUSIONS: Equipment-assisted intravesical instillation of MMC significantly reduced the recurrence and progression of patients with NMIBC who underwent TURBT and improved their quality of life. Given the significant heterogeneity in research quality and sample size among earlier studies, more prospective, multicentre, large sample randomized controlled trials are needed to supplement and verify this in the future.

Active Antioxidant Packaging from Essential Oils Incorporated Polylactic Acid/Poly(butylene adipate-co-terephthalate)/Thermoplastic Starch for Preserving Straw Mushroom.

The short-term shelf life of straw mushrooms (Volvariella volvacea) is a major challenge, hampering their wide distribution. Thus, the aim of this work was to develop a novel active packaging composed of essential oils (EOs), particularly clove oil (CO) and peppermint oil (PO), to reduce autolysis of straw mushrooms. The morphological characterizations, mechanical properties, barrier properties, and antioxidant activities of the films were characterized. The suppressive effects of the EOs on straw mushroom autolysis were estimated during storage at 16 ± 1 °C for 96 h. The results indicated that the addition of EOs weakened the mechanical and barrier properties of the films. The radical-scavenging activities of polylactic acid/poly(butylene adipate-co-terephthalate)/thermoplastic starch-peppermint oil (PLA/PBAT/TPS-PO) and polylactic acid/poly(butylene adipate-co-terephthalate)/thermoplastic starch-clove oil (PLA/PBAT/TPS-CO) films for 2,2-diphenyl-1-picrylhydrazyl were 56.0% and 91.3%, respectively. However, the PLA/PBAT/TPS-PO film was more effective in reducing polyphenol oxidase activity and maintaining the total phenol content of straw mushrooms, demonstrating better antioxidative activity. Mushrooms packaged with the PLA/PBAT/TPS-PO film exhibited the lowest autolysis rate (42.29%, p < 0.05) after 96 h of storage. Thus, PO is a good preservative agent for straw mushroom.

HS-GC-IMS identification of volatile aromatic compounds of freshly-cooked rice packaged with different disposable lunchboxes.

The rapid development of online-to-offline food delivery service has necessitated the replacement of plastic lunchbox using biodegradable ones. In current study, a total number of fourteen panelists were firstly recruited and trained to investigate how different commercial disposable lunchboxes affect the freshly cooked rice sensory properties during heat preservation (60 °C, 60 min). The lunchboxes were made of pure polypropylene (PP), polypropylene-starch (PP-S), pure wheat-straw and sugarcane-straw (WS & SS) and Paper. The discrepancy of volatile aromatic substances was then analyzed using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) to study the possible mechanism beneath the variations of the influences of different lunchboxes on the aromatic properties of rice. Results showed that, compared with the textural attributes, the aroma was significantly and positively correlated with panelist's acceptability, among which, the aroma of starchy, sulfur and smoky are the most important ones. The moisture absorption plays an important role in affecting the aromatic characteristics of the packaged rice. While all lunchboxes have inhibitory effects on the production of volatile flavor substances including 2,6-Dimethylpyrazine, 2-Acetylpyrazine and γ-Octalactone, pure PP and PP-S lunchboxes generated undesirable flavor substances including 2-Ethyl-1-hexanl and Camphene, and thus reduced panelist's preferences. It was also found that the panelist liked the rice packaged by Paper lunchbox the best because of its better performance in maintaining the aroma of starchy and sulfur, the two substances that are associated with the higher concentration of ethereal and fruity volatile flavor substances. This study provides important information for manufacturers to understand how different disposable lunchboxes may impact the textural and aromatic properties of packaged foods.

Controlled moisture permeability of thermoplastic starch/polylactic acid/poly butylene adipate-co-terephthalate film for the autolysis of straw mushroom Volvariella volvacea.

Straw mushrooms are prone to autolyze, leading to a high requirement of environmental humidity. In this work, thermoplastic starch/polylactic acid/poly (butylene adipate-co-terephthalate) (TPS/PLA/PBAT) film was produced by extrusion. The moisture permeability of the film was controlled by adjusting the content of TPS, which could be expected to further control humidity of the microenvironment in the package. Results revealed that the water vapor transmission rate of the film linearly increased from 612.31 g/m2·24 h to 1082.50 g/m2·24 h with the increase in the TPS concentration. The TPS/PLA/PBAT film with 30 wt% TPS showed the strongest inhibition on the autolysis of straw mushrooms compared with other groups, effectively delaying the increase in the free water, soluble solid content, rate of weight loss, and polyphenol oxidase of straw mushrooms and extending the shelf life of straw mushrooms from 24 h to 72 h.

Hollow tube covalent organic framework for syringe filter-based extraction of ultraviolet stabilizer in food contact materials.

In this work, a novel hollow tube covalent organic framework constructed by cyclotricatechylene and tetrafluoroterephthalonitrile (CTC-TFPN-COF) with polyether bond was synthesized, and it was coated on filter membrane for extraction of ultraviolet stabilizer in migration from food contact materials. Since the monomers of the polymer were linked by polyether bond, the CTC-TFPN-COF exhibited strong chemical stability in severe conditions such as acid, alkali and various organic solvent. The excellent features of high porosity and robust structure endowed the CTC-TFPN-COF good candidate as adsorbent for extraction of ultraviolet stabilizer. Moreover, the CTC-TFPN-COF coated membranes were immobilized on syringe filter and coupled with multiple channel injection pump to realize high throughput sample pretreatment strategy. Subsequently, a sensitive analytical method for ultraviolet stabilizer was established followed by ultra-high performance liquid chromatography-tandem mass spectrometry. The flow rate of extraction and desorption, elution solvent and the volume of desorption solvent were optimized. The method was assessed, which showed wide linear ranges with R2 greater than 0.99, low limits of detection (0.9-91 ng L-1) and low limits of quantification (3-300 ng L-1). The developed method was successfully applied to determine trace ultraviolet stabilizer in the migration of food contact materials with different simulated solution, which demonstrated its promising potential in practical analysis.

Method of Setting Environmental Administrative Fine Amounts.

In China, there are currently different degrees of arbitrariness in setting environmental administrative fines, and in many areas the faults are not equal to the penalties. To construct a more reasonable and feasible environmental punishment strategy where violators are fined in accordance with the severity of their actions, we use mathematical models to determine the specific range of environmental administrative fines based on the idea of realizing the appropriate balance between the interest of the violators and those of the public, meanwhile, law enforcement officers are allowed to use their discretion within a certain range. We use an example to prove that the punishment scheme provided by our models can be used to more effectively supervise violators' illegal behaviors than the penalty clause prescribed by law, and through sensitivity analysis and comparison, we prove that the described models are stable and feasible, and provide advantages over the existing methods. We hope our approach provides intellectual support for maintaining legal order, regulating the environmental administrative fine process, guiding business behaviors, and, most importantly, achieving the goal of protecting the environment.

Migration of mineral oil hydrocarbons from food contact papers into food simulants and extraction from their raw materials.

To determine the occurrence of mineral oil hydrocarbons (MOH) in food contact papers in China, and to investigate the potential sources of MOH contamination, a total of 159 food contact papers and raw materials were analysed by off-line solid-phase extraction-gas chromatography flame ionisation detection (SPE-GC-FID) and a GC-MS method. The migration of MOH from food contact papers into Tenax, olive oil or 50% ethanol under the worst foreseeable conditions of use was determined. The results indicated that the occurrence of MOH in China is of a potential health risk concerning the migration of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) which were detected in 82.6% and 50.4% of samples, respectively. Migration of MOSH from 47.9% of samples was higher than 2 mg/kg and migration of MOAH from 32.2% samples exceeded 0.5 mg/kg in case of the worst foreseeable condition of use. The highest mean migration of MOSH and MOAH were found in packaging papers for long-term storage (more than 6 months), with mean migration of 91.2 mg/kg and 1.4 mg/kg, respectively. Migration of MOH from printed paper was considerably higher than that of unprinted paper, validating previous findings that the printing ink is the predominant source of MOH contamination in food contact papers. Migration of MOH from paper bowls used for packing instant noodles was relatively low, suggesting the internal hollow layer may be acting as a functional barrier that could block the transfer of MOH (up to C28) through the gas phrase, even though the outer layer was made from recycled paper. High concentrations of MOSH and MOAH were also detected in de-foamers, adhesives and rosin sizing agents, indicating that the MOH contamination caused by the use of raw materials and additives should also be taken into consideration.

Effect of ionising irradiation on silver release from polyolefin/silver nanocomposite films into food simulants.

Two types of nanocomposite films, polyethylene/silver (PE/Ag) and polypropylene/silver (PP/Ag), were prepared and characterised. Assessment of silver released under the effect of ionising irradiation was performed on the nanocomposite films. The release experiment was carried out by immersing the nanocomposite films in water, 3% acetic acid or 95% ethanol as food simulants and measuring the Ag release from nanocomposite films treated with and without gamma or electron beam irradiation at a dose of 10 kGy. In general, irradiation treatment increased the Ag release regardless of the type of polymer and food simulant. One reason could be radiation-induced metal oxidation at the surface which in turn promoted ion release into food simulants. The oxidising radicals produced by radiation in solution could be another factor speeding up metal oxidation and subsequent ion release. When comparisons were made between the two types of irradiation, greater Ag release into water and 3% acetic acid was observed after electron beam irradiation, while gamma irradiation was likely to induce greater Ag release into 95% ethanol. Such phenomena reveal the influence of different types of radiation on the solutions which in turn affect the Ag release.

Influence of cooking conditions on the migration of silicone oligomers from silicone rubber baking molds to food simulants.

The stability, surface micromorphology, and volatile organic compounds (VOCs) of silicone rubber baking molds (SRBMs) were tested while using the molds under severe conditions: baking at 175 °C, microwaving at 800 W, and freezing at -18 °C. Moreover, migration tests of SRBMs to food simulants (isooctane, 95% ethanol, and Tenax®) at 70 °C for 2 h (accelerated conditions) were performed. The initial total VOCs concentration was 2.53% higher than that recommended by BfR Recommendations on Food Contact Materials. Therefore, the SRBM samples were considered as badly tempered materials, and 18 different types of silicone oligomers were identified during the migration tests. The following percentage of silicone oligomers with a molecular weight lower than 1000 Da in isooctane, 95% ethanol, and Tenax® were detected: 70.7%, 91.8%, and 97.2%, respectively. It has been proven that previous baking treatments effectively reduced the content of silicone oligomers migrating from SRBMs.

Sustained release of Ag+ confined inside polyoxometalates for long-lasting bacterial resistance.

A polyoxometalate hosting Ag+, [AgP5W30O110]14-, has been studied for its sustained and controlled release of Ag+ triggered by Na+ replacement at room temperature for long-lasting bacteriostasis, whose antibacterial activity is not eliminated after repeated exposure tests because of the protection of Ag+ by the polyoxometalate skeleton.

Influence of factors on release of antimicrobials from antimicrobial packaging materials.

Antimicrobial packaging materials (films or coatings) (APMs) have aroused great interest among the scientists or the experts specialized in material science, food science, packaging engineering, biology and chemistry. APMs have been used to package the food, such as dairy products, poultry, meat (e.g., beef), salmon muscle, pastry dough, fresh pasta, bakery products, fruits, vegetables and beverages. Some materials have been already commercialized. The ability of APMs to extend the shelf-life of the food depends on the release rate of the antimicrobials (AMs) from the materials to the food. The optimum rate is defined as target release rate (TRR). To achieve TRR, the influencing factors of the release rate should be considered. Herein we reviewed for the first time these factors and their influence on the release. These factors mainly include the AMs, food (or food simulant), packaging materials, the interactions among them, the temperature and environmental relative humidity (RH).

Molecular dynamics simulation of three plastic additives' diffusion in polyethylene terephthalate.

Accurate diffusion coefficient data of additives in a polymer are of paramount importance for estimating the migration of the additives over time. This paper shows how this diffusion coefficient can be estimated for three plastic additives [2-(2'-hydroxy-5'-methylphenyl) (UV-P), 2,6-di-tert-butyl-4-methylphenol (BHT) and di-(2-ethylhexyl) phthalate (DEHP)] in polyethylene terephthalate (PET) using the molecular dynamics (MD) simulation method. MD simulations were performed at temperatures of 293-433 K. The diffusion coefficient was calculated through the Einstein relationship connecting the data of mean-square displacement at different times. Comparison of the diffusion coefficients simulated by the MD simulation technique, predicted by the Piringer model and experiments, showed that, except for a few samples, the MD-simulated values were in agreement with the experimental values within one order of magnitude. Furthermore, the diffusion process for additives is discussed in detail, and four factors - the interaction energy between additive molecules and PET, fractional free volume, molecular shape and size, and self-diffusion of the polymer - are proposed to illustrate the microscopic diffusion mechanism. The movement trajectories of additives in PET cell models suggested that the additive molecules oscillate slowly rather than hopping for a long time. Occasionally, when a sufficiently large hole was created adjacently, the molecule could undergo spatial motion by jumping into the free-volume hole and consequently start a continuous oscillation and hop. The results indicate that MD simulation is a useful approach for predicting the microstructure and diffusion coefficient of plastic additives, and help to estimate the migration level of additives from PET packaging.