| Microcapsules prepared by compound condensation method have the advantages of simple operation,high payload and high encapsulation rate.Based on green coffee oil as the research object,this paper use gelatin in combination with different polysaccharide(gum Arabic,pectin,CMC)as the wall material,green coffee oil microcapsules were prepared by complex coacervation,Preparation of different combined wall green coffee oil microcapsule embedding performance and morphology were characterized,and then use the spectroscopy analysis of the structure,preparation of different combined wall green coffee oil microcapsule embedding performance and morphology were characterized,and then use the spectroscopy analysis of its structure,the study of the stability and digestive characteristics.It provides a theoretical basis and technical support for the high-value utilization of green coffee oil..The specific research contents and results of this paper are as follows:(1)To explore the influence of different wall material combinations on the microencapsulation of green coffee oil by composite condensation.The microcapsules of green coffee oil were prepared with gelatin-Arabic gum/pectin/sodium hydroxymethyl-cellulose by compound condensation method.The effects of three wall materials combinations on water content,yield,embedding rate,particle size and morphology of the microcapsules were studied.The results showed that the moisture content of microcapsule was less than 5%.The yield was over 90.0%,the embedding rate was over 85.0%,but the wall material utilization ratio was different,and the highest gelatin/pectin combination was 76.5%.The particle sizes are approximately 35.9?m,10.1 ?m and 51.2 ?m,respectively.The internal structure of green coffee oil wet microcapsules was observed by optical microscope,and it was found that green coffee oil microcapsules were spherical multicore microcapsules with complete structure,uniform dispersion and different sizes under the combination of three wall materials.Scanning electron microscope(SEM)was used to observe the surface structure of the microcapsules.The surface roughness of green coffee oil microcapsule was observed by atomic force microscope.The comprehensive analysis found that the three wall materials were successfully embedded.(2)The structures of composite condensate and microcapsule with different wall materials were studied.By ultraviolet spectrum,fluorescence spectra,Fourier infrared spectrum,nuclear magnetic resonance(NMR)and X-ray diffraction(XRD)technology on the gelatin-gum Arabic/pectin/CMC after polymer and the formation process of microcapsules were analyzed,and respectively showed that gelatin and polysaccharides interact in the process of the formation after polymer,molecular structure of gelatin conformational change,microenvironment of tyrosine from polar surface to hydrophobic internal;Gelatin and anion polysaccharide are formed by physical interaction such as electrostatic interaction,rather than by chemical interaction.There is no chemical reaction with wall material during the embedding process of green coffee oil.Gelatin and protein in the infrared spectra after polymer amide I belt fitting analysis showed that the compound polymer in beta-folding and random curl content are relatively reduced,relative increase of alpha beta rotating Angle and the spiral content;NMR confirmed that there was no other chemical reaction between the gelatin and the three polysaccharides.The composite condensation changed the crystallization characteristics of the wall material,and the green coffee oil also changed the crystallization characteristics of the compound polymer.(3)Study the performance of green coffee oil microcapsules.The thermal stability,storage stability and in vitro release characteristics of green coffee oil were studied.The contents of coffee bean alcohol and coffee alcohol,the representative substances of green coffee oil,were not affected after embedding.Thermogravimetric analysis of the complex polymers showed that the thermal stability of the complex polymers was related to the thermal stability of the wall material,and the thermal stability of the gelatin/CMC complex was the best,which significantly improved the thermal stability of green coffee oil through embedding.According to the accelerated storage test,the peroxide value,TBA and surface oil rate were used as evaluation indexes to study the stability of green coffee oil microcapsules.It was found that the peroxide value and TBA of green coffee oil after embedding increased very slowly,indicating that the oxidation stability of green coffee oil could be greatly improved after embedding.Through the in vitro simulated digestion experiment of gelatin-Gum/pectin/CMC composite agglomeration embedding green coffee oil microcapsules,the in vitro utilization rate of the microcapsules,particle size distribution in the digestion process,and microscopic observation were analyzed in the digestion process of the microcapsules,and it was found that the green coffee oil microcapsules could realize the slow-release effect.The core material can be well released in gastric and intestinal fluid,and the microcapsules can be digested and absorbed.In the simulated gastric juice,the green coffee oil complex microcapsules decomposed into emulsion state in the gastric juice,but still maintained obvious particle structure.After entering the simulated intestinal fluid,the emulsion recondensed into grape-like shape,and the particle structure of the complex disintegrated,leading to the slow release of green coffee oil.Studies have shown that gelatin-Arabic/pectin/CMC complexes can be used as encapsulation systems to protect bioactive compounds of interest in the food industry.Green coffee oil droplets can be encapsulated in a gelatin-Acacia/pectin/CMC complex using a compound condensation method.Relatively small and uniform microspheres were formed,and most of the lipid droplets were embedded in the interior,which could effectively improve the stability of green coffee oil and provide a theoretical basis for the high value of green coffee oil. |
PDF Full Text Request