Bacterial Cellulose As Novel Functional Pickering Stabilizer And Its Application In Encapsulation And Protection Of Vitamin E

Owing to the various nutritional and health functions,the fabrication of functional food system has become a focus in the field of food science.However,the current functional food has a single function,and usually over-packaged.As a result,it cannot meet consumers'needs with the continuously development of food industry and the increasing attention to consumers'health.Therefore,it is of great significance to develop novel raw materials and investigate the work mechanism of functional components.As a kind of novel dietary fiber,plant cellulose has been widely studied these years.Moreover,large of research has confirmed that cellulose nanofibrils or nanocrystals could adsorb into the oil-water interface and futher form a stable Pickering emulsion.However,there is little research about the usage of food-grade Pickering emulsion stabilized by bacterial cellulose nanofibrils?BCNFs?in the field of functional food system.In this thesis,bacterial cellulose?BC?was chosen as raw material to prepare cellulose nanofibrils as particle stabilizer for Pickering emulsion.Tea polyphenols?TPs?was further selected to adsorb into BCNFs,and the obtained complex,TPs/BC,was used as emulsifier model to prepare various oil-in-water Pickering emulsions to encapsulate hydrophobic vitamin E.All the results gathered here would improve the protective effect for hydrophobic bioactive components like vitamin E and widen the application of bacterial cellulose in functional Pickering emulsion system.1.High pressure homogenization?HPH?was applied to alter the physical size of bacterial cellulose.The average width of the BCNFs was decreased from 127 to 97 nm with the increasing homogenized times,and the obtained BCNFs suspension was pseudoplastic fluid and exhibited a typical shear thinning behavior.The physical size of the BCNFs had an obvious influence on their emulsifying capacity,and the surface coverage ratio of the emulsion droplets was increased from 0.63 to 9.77 with the changing the volume of oil and solid content of BCNFs.The basic mechanism of bacterial cellulose nanofibrils?BCNFs?for the stabilization of O/W emulsions was clarified.2.The main focus of the part was to explore the adsorption kinetics and interfacial properties of TPs/BC at the oil-water interface,which further contributed to fabricate an interfacial antioxidant.The mechanical strength of the formed O/W interfacial layer was increased from 58 to 130 mN/m.Meanwhile,emulsions stabilized by the physical complex was prepared,exhibiting excellent long-term stability.Moreover,the emulsions exhibited excellent free-radical scavenging activity at oil-water interface,indicating a potential application for the usage to extend the lifespan of the food containing polyunsaturated fats.3.The O/W Pickering emulsions were fabricated by using different contents of TPs/BC or various loading amounts of vitamin E.Through the initial trials,the TPs/BC?1:50?was selected for further study.Based on the results,it indicated that the encapsulation efficiency of vitamin E in the emulsion system was dependent on the particle contents and loading amount of vitamin E.Fe³⁺,Fe²⁺and Ca²⁺were chosen to study the influence of metal iron types and concentrations on the stability of emulsions.All the results had revealed that the obtained functional Pickering emulsion system exhibited excellent encapsulation efficiency and protective effects for hydrophobic bioactive components like vitamin E.