| In this study,using cassava starch as raw material,starch nanoparticles（SNPs）were prepared by ultrasonic-assisted alcohol precipitation method.By post-processing the SNPs obtained by sedimentation,the effect of high temperature treatment on the crystallinity of SNPs under the protection of absolute ethanol was studied;,using kaempferol and lutein as model molecules,the process of preparing starch nanoparticles by alcohol precipitation method was studied,and the drug was embedded and loaded simultaneously.The specific research contents and conclusions are as follows:The SNPs prepared by alcohol precipitation are all amorphous,and crystallinity is an important factor affecting the stability of SNPs and their application range.In this study,based on the preparation of SNPs,starch nanoparticles with certain crystallinity and good dispersibility were prepared by increasing the temperature to promote the solvent/non-solvent replacement process in the post-treatment.The effects of pretreatment temperature,treatment time,particle moisture content,and vacuum drying temperature on the crystallinity of precipitated particles were studied and compared during the post-treatment process of solvent replacement.X-ray diffraction（XRD）showed that the crystallinity of starch nanoparticles increased with the increase of treatment temperature.After solvent replacement treatment at 150℃for 3 h,SNPs formed V-type starch nanoparticle crystals;after further vacuum drying at 120℃,starch nanoparticles The relative crystallinity of nanoparticle crystals can reach up to 16.61%;field emission scanning electron microscopy（SEM）and laser nanoparticle size analyzer（DLS）found that the size of the prepared starch nanoparticle crystals is between200 and 400 nm,and the morphology is spherical or egg Round,well dispersed particles.Increasing the crystallinity of starch nanoparticles can effectively improve their stability.Compared with the control,the maximum decomposition rate of starch nanoparticles with 16.61%crystallinity increased from 307.4℃to315.9℃;within 1 h,the water solubility decreased by 57.14%,and the resistance toα-amylase hydrolysis increased by 13.16%.This study has certain guiding significance for the process improvement of the preparation of starch nanoparticles by alcohol precipitation.In order to discuss the preparation of starch nanoparticles during the sedimentation process to simultaneously realize the entrapment and loading of drug molecules,kaempferol starch nanoparticles（SNPs-kaempferol）were prepared by nano-sedimentation method with 0.7 mg/m L kaempferol solution as the non-solvent phase.The effects of ethanol concentration on the encapsulation rate and encapsulation amount of kaempferol were explored,and the effects of the encapsulation system on the release rate and stability of kaempferol were investigated.In addition,characterization was performed by field emission scanning electron microscopy（SEM）and laser nanoparticle size analyzer（DLS）.The results showed that the ethanol concentration had a great influence on the encapsulation rate and particle morphology.When the ethanol concentration was30%,the encapsulation rate of kaempferol was the highest,reaching 62.94%,but the starch nanoparticles aggregated;when the ethanol concentration increased to at60%,the morphology of SNPs is round or elliptical particles,and the size is uniformly distributed between 50 and 200 nm.At this time,the encapsulation rate is 9.31%.In the simulated body fluid environment,SNPs-kaempferol could be released continuously for 20 hours,with a release rate of 88.75%,while the original kaempferol drug under the same conditions had a release rate of 93.75%within 3 hours;When kaempferol was left standing at room temperature for 5 h,the retention rate of kaempferol increased from 43.17%to 75%.It can be seen that the nano-scale SNPs-kaempferol particles were prepared by the simultaneous embedding preparation technology,and the SNPs-kaempferol had a good effect of embedding slow-release and stabilizing kaempferol.In order to further study the loading mechanism of macromolecular hydrophobic drugs in the process of preparing starch nanoparticles by sedimentation,lutein starch nanoparticles（SNPs-lutein）were prepared with the alcoholic solution of lutein as the non-solvent phase.Under the reasonable balance of the two target parameters of lutein entrapment amount and entrapment rate,the concentration of starch milk was 4%,the concentration of lutein solution was 1mg/m L,and the volume ratio of starch milk to lutein alcohol solution was 5:10,the embedded amount of lutein was 32.67±0.36 mg/g,and the embedding rate was45.74±0.56%.SEM and DLS showed that synchronous entrapment of lutein had no significant effect on the morphology of SNPs,all of which were spherical or elliptical particles with smooth surface,with a size distribution between 200 and600 nm;Fourier transform infrared spectroscopy（FT-IR）showed that SNPs-Lutein formed a new characteristic absorption peak at 2856 cm-1,and the vibration shifted to a certain extent at 1645 cm-1;XRD showed that SNPs-lutein produced new peaks at 7.8°,13.1°and 20.9°V-starch characteristic peaks;iodine staining experiments showed that with the increase of the embedded amount of SNPs-lutein,the composite index（CI）gradually increased,andλmax had a red shift.The above results show that in the process of synchronously embedding lutein in the preparation of starch nanoparticles by sedimentation,the lutein molecules are embedded in the single helical cavity of the starch molecular chain.In this study,the surface of native starch granules was directly subjected to enzymatic hydrophobic modification to prepare rosin starch esters（RAS）with different degrees of substitution（DS）,and the adsorption differences of native starch and RAS on procyanidins（PC）were discussed.The results showed that RAS with DS of 0.00244,0.00811 and 0.0165 were synthesized;the adsorption results showed that the adsorption of RAS with DS of 0.00811 and 0.0165 to PC was faster and reached the adsorption equilibrium in 30 min;native starch and RAS with DS of 0.00244 had better adsorption Slowly,equilibrium is reached in45 min.Under the conditions of PC concentration of 9 mg/m L,temperature of25℃and adsorption time of 30 min,DS of 0.0165 can increase the adsorption capacity of native starch by 90.01%.In conclusion,the modified RAS can effectively enhance the adsorption effect of PC relative to native starch. |
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