Study On Preparation Of Multi-responsive Aroma Capsules Based On Emulsion Template Method

Flavor and fragrance are widely used in daily life due to their fragrant scent,antibacterial and antioxidant properties.However,these substances are generally unstable,susceptible to oxidation or deterioration and limit their application in complex environments to a certain extent.Environmental-responsive capsules enable the coated material to be released under different external stimuli,providing new chance for aroma releasing in complex environment.Based on the emulsion template method,this subject prepared multiple environmentally-responsive aroma capsules by interfacial polymerization and Pickering emulsion polymerization,respectively,and conducted research on their performance.The specific research content and results are as follows:（1）Using the emulsion formed by solubilizing linalool with the hydrolysis condensation product of dimethyldiethoxysilane（DMDES）as a template（lal@HCDS）,the temperature-sensitive monomer N-vinyl caprolactam（VCL）is polymerized by precipitation polymerization on the droplet surface to prepare temperature/redox responsive aroma（lal-HS-PVCL）capsules.The morphology and other performance of the capsule are characterized by transmission electron microscopy（TEM）,scanning electron microscopy（SEM）,infrared spectroscopy（FTIR）and thermogravimetry（TGA）.When VCL is used,a lal-HS-PVCL capsule with an average particle size of 1.4 μm and a loading rate of 50.41% is prepared.When the ambient temperature was 37 °C and the glutathione（GSH）concentration was 20 m M,the aroma release rate of the lal-HS-PVCL capsules increased by 40%,confirming that the lal-HS-PVCL capsules have good temperature and redox response characteristic.The 2,2-diphenyl-1-pyridohydrazino（DPPH）scavenging method was used to characterize the antioxidant properties.The free radical scavenging rate can be up to 28.65%.Plate count and confocal laser microscopy（CLSM）were used to characterize the bacteriostasis of the capsules.The results showed that after incubation with 1.1 mg / m L lal-HS-PVCL capsules containing 20 m M GSH at 37 °C,E.coli colonies were significantly reduced,indicating that the lal-HS-PVCL capsules had antibacterial response.（2）With nano-Si O₂ stabilized lemon oil Pickering emulsion as a template,p H-responsive composite capsules（LO@Si O₂@MPN）was prepared by polyphenol-metal ion complexation.Optical microscope,TEM,SEM toghther with UV spectraphotometer was performed to investigate the morphology and loading efficiency.When Fe CL3 is 18 mg/m L and the solid particle concentration is 1wt%,LO@Si O₂@MPN composite capsule with a particle size of 1.5± 0.5 μm is obtained,and its loading effciency is 70%.When the release rate is higher than p H 7 under p H 5,it shows good p H response release performance.At the same time,as an extension,a temperature-responsive composite capsule was prepared using the Pickering emulsion as a template.