Study On Preparation And Characterization Of Micro/Nano Starch Materials And Their Interaction With Two Kinds Of Food Components

As a renewable natural polysaccharide polymer,starch has various sources,low price,safe and low toxicity,and good biocompatibility.It is widely used in food,medicine and chemical industry.The research on the preparation of new food materials from starch as raw materials in the embedding and delivery of active ingredients,functional packaging,and food quality improvement has also received widespread attention.In addition,starch molecules are easy to modify and modify,and starch materials with different structures and properties can be designed for different research purposes to expand their application.Among them,the small-scale modification of starch to prepare micro/nano materials with unique characteristics has gradually become a hot spot in food nanotechnology research.In view of this,this study used two methods of chemical modification and nanotechnology modification to construct two typical micro/nano starch materials,namely starch microgel and starch nanofiber.According to their structural and functional properties,their interaction with two food ingredients(anthocyanin and stearic acid)was studied.The novel transporter was constructed by stabilizing the loading of anthocyanins by starch microgels.The structure of the starch chains and the structural changes of the assembled bodies were studied,and the effects on the transport protection and targeted release properties of anthocyanins were discussed.The direct formation of membranes by starch nanofibers was established.A new food packaging film was studied to study the self-assembly of stearic acid molecules and the modification of nanofiber interface,and to explore its regulation on the hydrophobic properties of starch nanofiber packaging film surface.The main research contents and results are as follows:1.Using corn starch as raw material,preheating with alcohol to reduce its crystallinity,and modifying starch by carboxymethyl anionization and quaternary ammonium cationization to prepare carboxymethyl anionic starch and quaternary ammonium cationic starch.The effects of etherification agent,catalyst and other factors on the degree of substitution were studied.Anionic starch with a degree of substitution of up to 0.325 and cationic starch with a degree of substitution of up to 0.316 were synthesized,and its apparent morphology,chemical composition,crystal structure,thermal stability,etc.The properties were characterized.The carboxymethyl anion starch and quaternary ammonium cationic starch were used as raw materials to prepare intelligent gel carrier by chemical cross-linking technology.Through elemental analysis and Fourier transform infrared spectroscopy,it was proved that sodium trimetaphosphate reacted with the anion-cationic starch hydroxyl group to form a phosphate bond.By studying the changes of potential and swelling of starch microgel under different environments,the stimulatory response of pH microgel under pH and I(Ionic strength)changes was clarified.The effects of chemical cross-linking on the micro-morphology,particle size distribution,elemental and structural composition and thermal stability of microgels were investigated by SEM,Malvern particle size analyzer and TGA.2.Using amylose as raw material,starch nanofibers were prepared by temperature assisted-electrospinning technology.The solubility of different concentrations of starch in spinning solvent(DMSO/water = 95/5,v/v)and its effect on the surface morphology of nanofibers by electrospinning were studied.The mechanical flexibility of the starch film composed of starch nanofibers was analyzed by visual physical folding experiments.The morphology of starch fibers prepared under different conditions was observed by SEM.The electrospinning process was further investigated by XRD and TGA.The influence of molecular crystallization and thermal stability.Considering the research results,the starch solution concentration is controlled at 25%,the working voltage is 20 KV,the receiving distance is 15 cm,and the solution flow rate is 1 mL/L.The starch nanofiber membrane with uniform microscopic morphology and uniform nanofibers can be obtained.Through the above research,an effective method for directly developing a membrane of starch nanofibers is obtained.3.Using anthocyanins(cyanidin-3-glucoside monomer)as a functional food factor,the layer-by-layer self-assembly technique was used to study the interaction between electrostatic and hydrogen bonding of starch microgels with different charging properties.The glycosides were assembled and embedded to obtain different layers of starch-based microgel-anthocyanin transporters.The interaction between the carrier materials during the reaction was investigated,and the assembled starch-based microgel-anthocyanins were simulated.The release behavior of active substances in the environment.Anthocyanins release less in simulated gastric fluid,and the release rate of anthocyanins in intestinal fluid is 73.5% and has good controlled release ability.4.Using molecular self-assembly to absorb the surface of nanofibers in starch membrane to form stearic acid molecular film,a controllable starch nanocellulose food packaging film was prepared,and its molecular weight was controlled by changing the concentration of stearic acid.Self-assembly process to obtain hydrophobic membranes of stearic acid modified starch nanofibers(SA/CSNFs)with different surface structures,and the morphology of SA/CSNFs composite membranes by SEM,contact angle test,EDS,XPS,XRD,etc.Surface infiltration,surface chemistry and crystal structure were studied to explore and reveal the relationship between surface micro-characteristics and functional properties of modified starch films.The results show that when the SA concentration is 0.1 M,the comprehensive performance of the hydrophobic membrane material is better,and the contact angle of the membrane surface reaches a maximum of 126.1o,which realizes the controllability of the hydrophobicity of the membrane surface.