Assessment of overall migration and specific migration of 1,4‐butanediol from a thermoplastic polyurethane film developed for fresh produce packaging

First occurrence and risk assessment of microplastics in enteral nutrition formulas

Occurrence and characteristics of microplastics were evaluated in enteral nutrition formulas, for the first time. A total of 30 samples belonging to 9 brands were analysed. Physical and chemical characteristics of microplastics were identified by stereomicroscopy and micro-raman spectroscopy, respectively. The mean number of microplastics was 45 ± 63 MP/L. Two different shapes of microplastics were detected with fibres (62%) being the most common microplastics followed by fragments (38%). The most common color of microplastics was black (37%) followed by blue (26%), orange (15%), green (7%), red (7%), grey (4%) and multicolor (4%). The length of microplastics ranged from 10 to 2086 μm with an average of 548 ± 526 μm. Estimated mean daily microplastic intake for four different scenarios varied between 24 to 61 and 30 to 76 MPs/day for women and men, respectively. The mean polymer hazard index and microplastic load index levels were calculated as 380 and 1.30, respectively. The results of this study showed that microplastics are prevalent in enteral nutrition products. The presence of polymers with high hazard risk scores in enteral nutrition formulas may pose a risk to the health of patients with special nutritional needs.

Obtention and Study of Polyurethane-Based Active Packaging with Curcumin and/or Chitosan Additives for Fruits and Vegetables-Part I: Analysis of Morphological, Mechanical, Barrier, and Migration Properties

Several polyurethane-formulated films with curcumin and/or chitosan additives for food packaging have been previously obtained. The study examines the effect of the additives on the film's morphological, mechanical, barrier, and migration properties. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water contact angle, thermogravimetric and differential thermal analysis (TGA and DTGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), oxygen transmission rate (OTR), water vapor transmission rate (WVTR), and the overall and specific migration tests were conducted. The results show that the presence of chitosan significantly increased the overall migration and mechanical properties, such as the elongation at break, tensile strength, and Young's modulus of most polyurethane formulations, while curcumin had a minor influence on the mechanical performance. Based on the results, formulations with curcumin but without chitosan are suitable for food packaging.

Integration of ARTP Mutation and Adaptive Laboratory Evolution to Reveal 1,4-Butanediol Degradation in Pseudomonas putida KT2440

Biotransformation of plastics or their depolymerization monomers as raw materials would offer a better end-of-life solutions to the plastic waste dilemma. 1,4-butanediol (BDO) is one of the major depolymerization monomers of many plastics polymers. BDO valorization presents great significance for waste plastic up-recycling and fermenting feedstock exploitation. In the present study, atmospheric pressure room temperature plasma (ARTP)-induced mutation combined with adaptive laboratory evolution (ALE) was used to improve the BDO utilization capability of Pseudomonas putida KT2440. The excellent mutant P. putida NB10 was isolated and stored in the China Typical Culture Preservation Center (CCTCC) with the deposit number M 2021482. Whole-genome resequencing and transcriptome analysis revealed that the BDO degradation process consists of β-oxidation, glyoxylate carboligase (GCL) pathway, glyoxylate cycle and gluconeogenesis pathway. The imbalance between the two key intermediates (acetyl-CoA and glycolyl-CoA) and the accumulation of cytotoxic aldehydes resulted in the weak metabolism performance of KT2440 in the utilization of BDO. The balance of the carbon flux and enhanced tolerance to cytotoxic intermediates endow NB10 with great BDO degradation capability. This study deeply revealed the metabolic mechanism behind BDO degradation and provided an excellent chassis cell for BDO further up-cycling to high-value chemicals. IMPORTANCE Plastic waste represents not only a global pollution problem but also a carbon-rich, low-cost, globally renewable feedstock for industrial biotechnology. BDO is the basic material for polybutylene terephthalate (PBT), poly butylene adipate-co-terephthalate (PBAT), poly (butylene succinate) (PBS), etc. Herein, the construction of BDO valorization cell factory presents great significance for waste plastic up-recycling and novel fermentation feedstock exploitation. However, BDO is hard to be metabolized and its metabolic pathway is unclear. This study presents a P. putida mutant NB10, obtained through the integration of ARTP and ALE, displaying significant growth improvement with BDO as the sole carbon source. Further genome resequencing, transcriptome analysis and genetic engineering deeply revealed the metabolic mechanism behind BDO degradation in P. putida, this study offers an excellent microbial chassis and modification strategy for plastic waste up-cycling.