Study On Improvement Of Properties Of Konjac Glucomannan Films By Pickering Emulsion

So far,Konjac glucomannan(KGM)has become a popular biological material due to its wide distribution,low price,biodegradable and other advantages.It is mostly used to prepare and form gels or functional films for food,medicine and material industries.Although KGM,as a food hydrocolloid,has excellent water retention ability,stability,film forming property,thickening property and emulsification property,at the same time,the film materials prepared and developed by KGM alone have poor mechanical properties,insufficient thermal stability and other shortcomings,and also lack of functions such as antibacterial and antioxidant properties.Therefore,in recent years,the research related to its film formation focuses on the modification of KGM,polymerization of KGM with other substances and so on.In order to make KGM-based films with antibacterial properties,many researchers imagine adding essential oil and other substances with antibacterial properties to KGM.However,when directly added,the extracts cannot be evenly dispersed in the polysaccharide film,which seriously damages the mechanical and water vapor barrier properties of the composite film.Therefore,the idea of embedding functional substances in KGM film comes into being.Ideally,the experimenters would like to be able to give the KGM composite membrane functionality,while at the same time,the composite material can improve the performance of KGM.In this case,the idea of mixing Pickering emulsion with konjac glucomannan to form a film gradually attracted attention.β-cyclodextrin(β-CD)is currently a common and relatively mature and stable material for the preparation of Pickering emulsions,due to the special structure of its hydrophobic cavity and hydrophilic exterior,which enables it to form inclusion complexes with amphiphilic non-polar molecules or hydrophobic parts.It has been shown that β-CD can be complexed with substances,resulting in a strong synergistic effect of surface activity and aggregation behavior,which is beneficial to the adjustment and optimization of functional properties.At the same time,the essential oil is encapsulated in a hydrophilic material and dispersed in a polymer matrix,which reduces the direct contact between the essential oil and the polysaccharide and enables it to disperse more evenly.In addition,Pickering emulsion can increase the miscibility of essential oil and improve the functional properties of composite film.Therefore,in order to adjust the physical and chemical properties and functional properties of Konjac glucomannan films,Pickering emulsion and KGM were used to form films.Firstly,based on the background that Pickering emulsion loaded with eugenol has never been studied,Pickering nano-emulsion loaded with oil phase(eugenol)of different concentrations with β-cyclodextrin and sodium caseinate(SC)as stabilizer was prepared.The oil phase concentrations were 3%,5% and 10%,respectively.Through particle size analysis,stability investigation,Fourier infrared spectroscopy and other relevant characterization of Pickering emulsion,the conclusion is drawn: The particle size ranges from 87.94±0.64 nm to145.79±1.25 nm,and the stability can be up to 90 days.Infrared assisted proof that eugenol can be successfully embedded in Pickering emulsion,fully evaluate the feasibility of β-CD stable Pickering emulsion with eugenol as oil phase.This pave the way for the development of stable and functional active emulsion films.Secondly,on the basis of the first experimental study,Pickering emulsion with a stable oil phase of 3% was kept as the research object.By adjusting the content of Pickering emulsion in the composite film system and comparing the loading mode of eugenol,the differences of mechanical properties,thermal stability,antioxidant and antibacterial properties between pure KGM film and composite film were explored.The results show that due to the strong interaction between the Pickering particles with different concentrations of eugenol and KGM,the mechanical strength of the composite films is significantly enhanced,and the maximum tensile strength and elongation at break can reach27.45 MPa and 55%,respectively.The addition of emulsion can prevent the thermal degradation and decomposition of components in the composite film material,so as to improve the thermal stability of the composite film.Meanwhile,Pickering-KGM film showed good inhibition against Staphylococcus aureus.Subsequently,another experiment was conducted to explore the influence of Pickering emulsion with different particle sizes on KGM composite film by keeping the relative oil content of the composite film unchanged.After Fourier infrared spectroscopy,X-ray diffraction,scanning electron microscopy and other test results,as well as mechanical strength,elongation at break,antibacterial and antioxidant properties,it is known from the appearance that with the increase of the particle size of Pickering emulsion,the surface and cross section of KGM-based film will become rough or have more particles.The overall inhibition of Staphylococcus aureus was also enhanced.In addition,the addition of Pickering with different particle sizes can improve the water resistance and oxidation resistance of KGM films.At the same time,the addition of 3%-2 Pickering could significantly improve the tensile strength and fracture elongation of the film(p<0.05).In conclusion,the successfully prepared Pickering emulsion loaded with eugenol can significantly improve the mechanical properties and thermal stability of KGM film through molecular forces such as electrostatic action and hydrogen bonding on the basis of not destroying the original structure of KGM,and make the composite film have certain antibacterial and antioxidant properties.Therefore,this study effectively improves the performance of KGM film,making it have application potential in the field of food packaging.