| BackgroundThe cultivation and production of fruits and vegetables in China are among the highest in the world,but due to the backward post-harvest preservation technology,the post-harvest loss rate is as high as 20%to 30%,much higher than the level of developed countries(5%),causing an annual economic loss of about 80 billion yuan.With the increasing consumer demand for fresh fruit and vegetable quality,the urgent need to develop more advanced fruit and vegetable storage and preservation technology.According to the physiological characteristics of post-harvest fruits and vegetables,equilibrium modified atmosphere packaging can effectively reduce the respiration and transpiration metabolic rate of fruits and vegetables by adjusting the O2 and CO2 concentration inside the package,thus extending the storage and preservation period of fruits and vegetables.Polyether ether ketone(Poly Ether Ether Ketone,PEEK)is a special engineering plastic with excellent performance,after sulfonation modification,its permeability and moisture permeability has been significantly improved,and is expected to be used in modified atmosphere packaging.However,modified polyether ether ketone aerosol packaging films used as food contact materials may interact with food,and small molecules in the material may migrate into the food and pose health risks,so the safety of the migrated materials needs to be further studied.Objectives1.To investigate the effect of polyether ether ketone modified and blends on the structure and properties of the materials.2.To evaluate the preservation effect of blended films applied to strawberry modified atmosphere preservation.3.To investigate whether there is any health risk of the prepared blended materials used as food contact materials.Methods1.The sulfonated poly ether ether ketone(SPEEK)materials were prepared by concentrated sulfuric acid co-heating method,and blended with thermoplastic polyurethanes(TPU)materials to produce blended films with different blending ratios,and characterized by scanning electron microscopy,infrared The structure of the materials were characterized by scanning electron microscopy and infrared spectroscopy,and the properties of the materials were characterized by gas and water vapor permeability coefficients,water contact angle,tensile strength,etc.2.The prepared blended films were applied to the modified atmosphere preservation of strawberries,and the preservation effect of the blended films applied to the modified atmosphere preservation of strawberries was evaluated by testing the changes of ascorbic acid,total phenols,anthocyanins,soluble solids,titratable acids,etc.during the storage process.3.A database of plastic-related food packaging materials was constructed in combination with Python technology to assist in the identification and characterization of migration,followed by the identification and characterization of migration and potential migration in PEEK materials and SPEEK/TPU blended films using high-resolution mass spectrometry non-targeted screening techniques.Exposure levels of the migrates were assessed by quantitative/semi-quantitative methods and compared to their corresponding TTC thresholds to assess the safety of the materials.In addition,a risk classification strategy was used to analyze the higher risk substances in the potential migration of PEEK materials.Results1.The prepared SPEEK/TPU blends were dense films with good compatibility,dense and flat surfaces and cross-sections,and no penetration holes or foam pores.Meanwhile,the addition of TPU lightened the yellow-green color of the film(P<0.05),improved the flexibility of the material(P<0.05),reduced the hydrophilicity and moisture permeability of the film(P<0.05),and reduced the permeability and selective permeability of the film to CO2(P<0.05).2.Application of SPEEK/TPU blended films to strawberry modified atmosphere preservation reduced weight loss(P<0.05),maintained the surface morphology of strawberries,delayed the decrease in color(brightness,total color difference)and hardness(P<0.05),delayed the flavor characteristics such as soluble solids and organic acids(P<0.05)and antioxidant bioactive substances such as ascorbic acid,total phenols and anthocyanins(P<0.05).It also inhibited malondialdehyde accumulation in strawberries(P<0.05),slowed down the process of film lipid peroxidation and prolonged the storage shelf life of strawberries,among which BM25 film was the most effective for balanced modfied mosphere packaging of strawberries.3.The safety evaluation of PEEK and BM25 blends was conducted separately.43 potential migration substances were identified in the PEEK pellets and finished films,among which the sulfate anionic antistatic agents should be focused on,and a total of 4 migration substances were identified in the PEEK films,with exposure levels below their TTC thresholds.A total of 22 potential migrators were identified,among which N-nitro morpholine should be the focus of attention,but this substance did not migrate out,and the exposure level of antistatic agent tetrabutylammonium in the migrators exceeded its TTC threshold,suggesting that BM25 blends have health risks and should be further evaluated in combination with in vitro biological experiments.ConclusionSPEEK/TPU blended films are suitable for balanced modified atmosphere packaging of strawberries,which can retard the quality change of strawberry,but the exposure level of tetrabutylammonium migration is higher than its TTC threshold,and further risk assessment is needed if the material is to be used as a food contact material. |
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