Poly(lactic acid)(PLA)has limited promise as a bio-based antimicrobial packaging material due to its lack of plasticization,which limits antimicrobial agent release and antimicrobial efficiency.PLA were plasticized wi...Poly(lactic acid)(PLA)has limited promise as a bio-based antimicrobial packaging material due to its lack of plasticization,which limits antimicrobial agent release and antimicrobial efficiency.PLA were plasticized with polyethylene glycol(PEG)and blended with ethyl maltol or ethylenediaminetetraacetic acid(EDTA)as antibacterial agents by melt extrusion.The effects of combining PEG,EDTA,and ethyl maltol on sheet properties and antibacterial activity were investigated.Incorporation of ethyl maltol created a dense and smooth homogeneous surface,while EDTA addition caused large pores in the PLA sheet microstructure impacting swelling degree,water solubility and surface hydrophilicity.Fourier transform infrared(FTIR)spectroscopy and differential scanning calorimetry(DSC)showed that both ethyl maltol and EDTA addition modified the amorphous and crystalline phases of plasticized PLA.FTIR results suggested interaction between the functional groups of PLA chains,PEG,ethyl maltol or EDTA which affected the glass transition temperature(T_(g)),degree of crystallinity,and thermal stability of PLA.Adding PEG into PLA-EDTA enhanced antibacterial activity against Gram-positive Staphylococcus aureus(reduction of 1.35 log CFU/mL from the initial inoculum).The higher water solubility of sheets corresponded to a suitable release rate and sufficient amounts of antimicrobial compounds against Staphylococcus aureus.In vitro antifungal testing,PLA-PEG-EDTA sheets did not exhibit a clear zone of inhibition but delayed Penicillium sp.spore formation until day 5 of incubation.PEG plasticized PLA sheets functionalized with ethyl maltol and EDTA showed potential as active biomaterials against food-borne pathogen bacteria Staphylococcus aureus.展开更多
Novel nanocomposite poly(butylene adipate-co-terephthalate)(PBAT)/polybutylene succinate(PBS)blend films functionalized with titanium dioxide(TiO_(2))nanoparticles(0,0.9,1.8,2.7,3.6 and 4.5%w/w)were produced using cas...Novel nanocomposite poly(butylene adipate-co-terephthalate)(PBAT)/polybutylene succinate(PBS)blend films functionalized with titanium dioxide(TiO_(2))nanoparticles(0,0.9,1.8,2.7,3.6 and 4.5%w/w)were produced using cast-sheet extrusion.Atomic force microscopy,X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR)and dynamic mechanical thermal analysis were used to investigate film morphology and structure.The crystallinity of the films was modified due to interactions between the nanoparticles and the PBAT/PBS blends,as confirmed by FTIR and XRD.Tensile strength and elongation of films slightly reduced with TiO_(2)addition up to 4.5%in both machine direction(MD)and cross direction(CD).The tensile strength of the T5 films was nearly 25%less than the control films.Adding TiO_(2)gave excellent UV-blocking properties with slightly reduced water vapor by 16.5%and oxygen permeability by 4%for films with maximum loading.The film surface became more hydrophilic,as evidenced by the reduced contact angle.The results,as acquired from turbidity measurements,show that films with 3.6%TiO_(2)loading and above have high antimicrobial activity against both Bacillus cereus(Gram-positive)and Escherichia coli(Gram-negative).The relative area of microbial growth on agar media exhibited better antibacterial capacity against Escherichia coli than Bacillus cereus,with a sharp reduction of microbial growth at TiO_(2)contents above 2.7%.Films containing TiO_(2)(≥0.9%)effectively delayed ripening and increased peel yellowness of packaged bananas during storage for 6 days at room temperature.The developed PBAT/PBS/TiO_(2)nanocomposites films hence showed enhanced UV-resistance and antimicrobial properties,while maintaining adequate mechanical strength necessary for food packaging.The film is an eco-friendly alternative antimicrobial food packaging to extend the shelf-life of fresh produce.展开更多
基金supported by Kasetsart University Research and Development Institute(KURDI),Kasetsart University,Thailand,FF(KU)5.67.
文摘Poly(lactic acid)(PLA)has limited promise as a bio-based antimicrobial packaging material due to its lack of plasticization,which limits antimicrobial agent release and antimicrobial efficiency.PLA were plasticized with polyethylene glycol(PEG)and blended with ethyl maltol or ethylenediaminetetraacetic acid(EDTA)as antibacterial agents by melt extrusion.The effects of combining PEG,EDTA,and ethyl maltol on sheet properties and antibacterial activity were investigated.Incorporation of ethyl maltol created a dense and smooth homogeneous surface,while EDTA addition caused large pores in the PLA sheet microstructure impacting swelling degree,water solubility and surface hydrophilicity.Fourier transform infrared(FTIR)spectroscopy and differential scanning calorimetry(DSC)showed that both ethyl maltol and EDTA addition modified the amorphous and crystalline phases of plasticized PLA.FTIR results suggested interaction between the functional groups of PLA chains,PEG,ethyl maltol or EDTA which affected the glass transition temperature(T_(g)),degree of crystallinity,and thermal stability of PLA.Adding PEG into PLA-EDTA enhanced antibacterial activity against Gram-positive Staphylococcus aureus(reduction of 1.35 log CFU/mL from the initial inoculum).The higher water solubility of sheets corresponded to a suitable release rate and sufficient amounts of antimicrobial compounds against Staphylococcus aureus.In vitro antifungal testing,PLA-PEG-EDTA sheets did not exhibit a clear zone of inhibition but delayed Penicillium sp.spore formation until day 5 of incubation.PEG plasticized PLA sheets functionalized with ethyl maltol and EDTA showed potential as active biomaterials against food-borne pathogen bacteria Staphylococcus aureus.
基金financially supported by Kasetsart University Research and Development Institute(KURDI)FF(KU)25.64the Office of the Ministry of Higher Education,Science,Research and InnovationThailand Science Research and Innovation through the Kasetsart University Re-inventing University Program 2022.
文摘Novel nanocomposite poly(butylene adipate-co-terephthalate)(PBAT)/polybutylene succinate(PBS)blend films functionalized with titanium dioxide(TiO_(2))nanoparticles(0,0.9,1.8,2.7,3.6 and 4.5%w/w)were produced using cast-sheet extrusion.Atomic force microscopy,X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR)and dynamic mechanical thermal analysis were used to investigate film morphology and structure.The crystallinity of the films was modified due to interactions between the nanoparticles and the PBAT/PBS blends,as confirmed by FTIR and XRD.Tensile strength and elongation of films slightly reduced with TiO_(2)addition up to 4.5%in both machine direction(MD)and cross direction(CD).The tensile strength of the T5 films was nearly 25%less than the control films.Adding TiO_(2)gave excellent UV-blocking properties with slightly reduced water vapor by 16.5%and oxygen permeability by 4%for films with maximum loading.The film surface became more hydrophilic,as evidenced by the reduced contact angle.The results,as acquired from turbidity measurements,show that films with 3.6%TiO_(2)loading and above have high antimicrobial activity against both Bacillus cereus(Gram-positive)and Escherichia coli(Gram-negative).The relative area of microbial growth on agar media exhibited better antibacterial capacity against Escherichia coli than Bacillus cereus,with a sharp reduction of microbial growth at TiO_(2)contents above 2.7%.Films containing TiO_(2)(≥0.9%)effectively delayed ripening and increased peel yellowness of packaged bananas during storage for 6 days at room temperature.The developed PBAT/PBS/TiO_(2)nanocomposites films hence showed enhanced UV-resistance and antimicrobial properties,while maintaining adequate mechanical strength necessary for food packaging.The film is an eco-friendly alternative antimicrobial food packaging to extend the shelf-life of fresh produce.
