Preparation,characterization And Application Of Cyclodextrin And Cyclodextrin Composites Stable Emulsions

β-Cyclodextrin（β-CD）and its inclusion complexes can be used as emulsifiers for food-grade Pickering emulsion,but the stabilizatin mechanism of this both emulsifiers for emulsions have little been reported.Fatty oxidative rancidity affects the taste,flavor and shelf life of emulsion foods.The development of green,safe Pickering emulsions with antioxidant activity is one of the current research hotspots in the food field.In this paper,the process of preparing Pickering emulsion fromβ-CD was optimized based on single factor and orthogonal experiments.The cinnamaldehyde（CEO）/β-CD inclusion complex was prepared,and its structure and properties were studied.Pickering emulsions were prepared with inclusion complexes as stabilizers,and the morphology,stability,particle size,potential and rheological properties of these emulsions were systematically studied.The stabilization mechanism ofβ-CD and its inclusion complexes was thoroughly studied,and the antioxidant and anti-digestive properties of Pickering emulsion were compared.The main research contents,methods and relevant conclusions of this thesis are as follows:（1）Based on the results of single factor and orthogonal experiment,the optimal process for preparing Pickering emulsion withβ-CD as emulsifier was determined:the addition amount ofβ-CD was 3%（w/v）,and the volume fraction of oil phase was 60%.（v/v）,the dispersion time was 3 min,and the rotational speed was 25000 r/min.The Pickering emulsion prepared under the optimal preparation process has good stability,the emulsion particle size is 10.49±0.81μm,and the absolute value of zeta potential is 33.40±3.54m V.（2）A white flocculent cinnamaldehyde/β-CD inclusion complex was prepared,and the entrapment rate of CEO was 91.74±0.82%.The infrared characteristic absorption peaks of CEO at 1680 cm^-1,1626 cm^-1,748 cm^-1,etc.disappeared in the inclusion complex.The inclusion complex of CEO andβ-CD was formed by inclusion complexation,and the characteristic X-ray diffraction peaks ofβ-CD at 4.86^o,14.92^o,19.08^o,etc.disappeared in the inclusion complex.After the introduction of CEO,the three-phase contact angle ofβ-CD increased from 22.74^o（±2.33^o）to 39.74^o（±0.90^o）.（3）Inβ-CD stabilized Pickering emulsions,with the increase ofβ-CD concentration,the emulsion droplet size first decreased and then increased slowly.When the addition amount ofβ-CD was 3%（w/v）,the minimum particle size of the emulsion was 10.49±0.8μm,and the absolute value of zeta potential was 33.40±3.54 m V.The emulsion had good stability.Scanning electron microscope results ofβ-CD stabilized Pickering emulsions showed that with the increase ofβ-CD content,the thickness of the protective shell of the emulsion droplets increased.As the concentration of CEO/β-CD inclusion complex increased from 1%（w/v）to 5%（w/v）,the emulsion droplet size decreased from26.14±2.15μm to 9.90±0.69μm.When the addition amount of inclusion compound was 2%（w/v）,the inclusion compound emulsion has good storage stability.Compared with theβ-CD-stabilized emulsion,the inclusion complex emulsion had smaller particle size,lower stabilizer usage,higher emulsion stability,as well as the lower storage modulus,loss modulus and viscosity.（4）The stabilizatin mechanism ofβ-CD and inclusion complexes for Pickering emulsions as belows:At low concentrations,theβ-CD and inclusion complexes both stabilized the emulsion through forming a single-layer emulsion interfacial film at the oil-water interface in molecular form.At high concentration,the stabilization mechanism ofβ-CD and its inclusion complexes for Pickering emulsion was significantly different.Forβ-CD,the crystallizes was formed firstly and then aggregated at the oil-water interface film to form a multi-layered emulsion protective shell.In addition,partialβ-CD dissolved in the continuous phase to increase emulsion stability and viscosity.In contrast,theβ-CD inclusion complexes at high concentration formed a single-layer emulsion protective shell,and excess inclusion complexes uniformly distributed in the continuous phase to form a network structure,based on which stabilized the Pickering emulsion.（5）β-CD and CEO/β-CD inclusion complex had good emulsifying effect on a variety of oil phases,including lard,fish oil,soybean oil and linseed oil,and from all of which could form the emulsions with thermally stable.For the same oil phase,theβ-CD emulsion had higher hardness,chewiness and storage modulus,but lower the cohesion.（6）The emulsion prepared byβ-CD and CEO/β-CD inclusion complex emulsified soybean oil was used as a model for further study.The main absorption site of this emulsion was in the small intestine.Compared withβ-CD emulsion,the free fatty acid was released more rapidly in the inclusion complex emulsion.The results of antioxidant experiments showed that Pickering emulsion had better antioxidant properties than traditional emulsions,and the strongest antioxidant capacity was found in the inclusion compound emulsion containing CEO molecules.In detail,after 28 days of storage,the content of malondialdehyde in the inclusion compound emulsion was only 217.43 nmol/L.