The Preparation And Antibacterial Performance Of Allicin Pickering Emulsion-sodium Alginate Based On Antibacterial Packaging Film

This thesis is an extension of project“Preparation and Performance of Polylactic Acid/picoline Emulsion Double-layer Composite Film Antibacterial Packaging Materials”（No.20200201107JC）of the Jilin Provincial Science and Technology Development Program.The traditional plastic package causes a variety of environmental problems,so more researchers begin that pay attention to green biodegradable and renewable packaging materials.The sodium alginate is a natural polysaccharide polymer material which has excellent film-forming properties in addition to being green.And it can be used as an anti-bacterial packaging substrate.The allicin owns natural broad-spectrum bacteriostatic ability as an active bacteriostatic agent in packaging.However,the weak stability of allicin is easily decomposed and dissipated during normal membrane process.Thus,it is hardly soluble in water,so it is relatively difficult to be utilization.Therefore,the encapsulation technology can effectively use to develop antibacterial packaging films with better performance.In this research,we use octenyl succinate denatured starch as solid particles to prepare encapsulated allicin in Pickering emulsion to improve the stability of allicin based on the investigation of the bacterial inhibition mechanism of allicin.The sodium alginate is taken as base material to prepare the antibacterial film with adding Pickering emulsion and nanocellulose.The antibacterial mechanical properties active packaging become excellent.The details of this research and its findings are as follows:（1）Network Pharmacology of Allicin Bacteriostatic MechanismThrough network pharmacology,it finds that allicin has 66 antibacterial interaction targets.Among them,EGFR,MAPK3,CASP3,STAT1,MAP2K1 are the core targets.It indicates that allicin mainly acts as an antibacterial agent through MAPK signaling pathway,TNF signaling pathway,PI3K-Akt signaling pathway and HIF-1 signaling pathway,binding with epidermal growth factor,negatively regulating cell cycle,inducing apoptosis,affecting bacterial related protein synthesis,response to lipopolysaccharide and response to drugs.It proves that allicin has multi-target and multi-pathway mechanism of bacterial inhibition.（2）Bacteriostatic Effect and Stability of AllicinThe bacteriostatic stability of allicin under various conditions is researched,and typical gram-negative bacteria-Escherichia coli and gram-positive bacteria-Bacillus subtilis are selected as indicator bacteria.The results show that the minimum inhibitory concentrations of allicin against Escherichia coli and Bacillus subtilis are 2.5μL/m L and 1μL/m L,respectively,and the bacteriostatic ability of allicin gradually decreased with the effects of ultraviolet irradiation,heating,p H increase and prolonged storage time,indicating that allicin had strong bacteriostatic effect but was unstable in itself.（3）Preparation and Performance of Allicin MembraneThe effect of addition of each component on the mechanical properties（EB,TS）and barrier properties（OP,WVP）of the antibacterial packaging film is analyzed by the single-factor method,and the SVR model with RBF as the kernel function is used to determine the packaging in a certain optimal additions in a certain range were:1.9%（w/v）for sodium alginate,3.5%（v/v）for glycerol,2.5%（v/v）for nanocellulose,and 0.45%（v/v）for allicin.The optimal films are prepared that the measured performance indexes are:thickness of about0.098 mm,EB of 9.37±1.29%,TS of 31.09±1.18 MPa,OP of 0.39±0.09×10^-5 g/（m²·d·Pa）,WVP of 1.32±0.28×10^-12 g/（cm·s·Pa）,and FTIR and SEM are used to characterize the molecular structure and microscopic morphology.（4）Preparation and Properties of Allicin Pickering Emulsion FilmWith comparing different emulsion morphologies,the emulsion is finally preparation with a 4:1 ratio of OSA:Ac.Its diameter is about 462.73 nm,ξpotential is-26.033 m V,PDI value is 0.175,and a uniform and fine morphology.The emulsion adds to the antibacterial film with sodium alginate and nanocellulose as base material and glycerol as the plasticizer,and the effect of the addition amount of each component on TS,EB,OP and WVP of antibacterial emulsion film is analyzed by the single factor method;the optimal addition amount of each component for packaging within a certain range was determined by the principal component analysis and SVR model with RBF as the kernel function:the addition amount of sodium alginate is 1.05%（w/v）,glycerol addition of 1.75%（v/v）,nanocellulose addition of 1.85%（v/v）,picolin emulsion addition of 5.05%（v/v）,and allicin content of 1.26%（v/v）to prepare the optimal film,and measurement performance indexes are film thickness of about 0.113 mm,EB of 95.01±4.86%,TS of 9.62±1.61 MPa,0.55±0.06×10^-5 g/（m²·d·Pa）for OP,0.98±0.01×10^-12 g/（cm·s·Pa）for WVP,and the molecular and micromorphological structures of optimal emulsion films are characterized by FTIR and SEM.Finally,the bacterial inhibitory properties of allicin-sodium alginate film and optimal group of emulsion film are investigated,and the PE film is found to be superior to the allicin-sodium alginate film without encapsulation.It indicates that the mechanical properties and bacterial inhibitory properties of the produced allicin-picoline emulsion-sodium alginate membrane are superior to those of allicin-sodium alginate membrane.