Microencapsulation Of Fragrance And Synthesis,Characterization And Preparation Of Latent Fragrance

Ethyl vanillin is widely used in food,medicine,cosmetics and other fields as a fragrance additive because of its strong and unique vanilla odor.The fragrance of ethyl vanillin is several times that of vanillin.It is non-toxic and harmless.It is a substitute for vanillin and has broad prospects.However,its solubility in water is not good(slightly soluble)and is very unstable.It will be oxidized in long-term light or exposed to the air,and the aroma and fragrance are volatile.In this paper,the co-crystal principle is used to prepare fragrance co-crystal latent fragrance material and fragrance microencapsulation.On the one hand,it improves the storage stability of ethyl vanillin and protects aroma substances;on the other hand,it improves the thermal stability of ethyl vanillin and has a certain slow-release effect.The main research contents were as follows:1.Using urea and thiourea as the substrate,anhydrous ethanol as the solvent,the room temperature solvent volatilization method was used to prepare co-crystals with ethyl vanillin,and the ethyl vanillin-urea co-crystal and the ethyl vanillin-thiourea co-crystal are obtained.The structure and thermodynamic properties of the prepared ethyl vanillin co-crystal compound were characterized by infrared spectroscopy and thermogravimetric test.X-single crystal diffraction confirmed the crystal structure of ethyl vanillin-urea co-crystal.Ethyl vanillin-urea co-crystal is yellowish needle-like crystal,belonging to the orthorhombic crystal system(orrhombic crystal system),and the Pmna space group.2.The Hirshfeld Surface analysis of the ethyl vanillin-urea co-crystal was further carried out,which showed that the co-crystal presented strong N-H???O,C-H???O and O-H???O intermolecular forces,which is expected to provide theoretical support for the design of aromatic aldehyde fragrance co-crystals.In addition,the thermogravimetric analysis results showed that the thermal stability of the co-crystal compound has been improved.Therefore,using the principle of co-crystals to prepare ethyl vanillin latent aroma compounds can improve the thermal stability of ethyl vanillin,and at the same time can slowly release aroma substances.3.Using the ring-opening polymerization method,m PEG used as the macromolecular initiator,and under the action of the catalyst stannous octoate,the ring-opening polymerization of L-lactide was initiated to prepare amphiphilic blocks with different ratios of hydrophobic and hydrophilic chains.The structure and chemical composition of the copolymer m PEG-PLA meet the expectations.Next,using ethyl vanillin with a strong vanilla odor as the core material and the prepared amphiphilic block copolymer m PEG-PLA as the wall material,ethyl vanillin microcapsules were prepared by the emulsification-solvent volatilization method.Using orthogonal experiments,we fixed the oil-water volume ratio,selected the appropriate core-wall ratio and solvent volatilization method,and optimized the selection of the amphiphilic block copolymer concentration,homogenization time,oil phase solvent and emulsifier.The prepared flavor microcapsules have relatively round morphology,good dispersibility,and ideal flavor loading rate.4.Studies on the thermal properties and stability of the fragrance microcapsules showed that the storage stability of the prepared fragrance microcapsules was improved.In addition,the volatility of the fragrance was reduced under high temperature,and it had a certain slow-release effect.