Preparation And Characterization Of Water Soluble Starch Based Nanoparticle Carrier

Naturally existed water soluble starch is a kind of plants originated and highly branched glucan.It provides plants with energy and is also known as phytoglycogen.Without crystalline zone,water soluble starch has a special hyperbranched structure with short chains,which contributes to its high solubility,low viscosity and slow digestibility.The presence of large amounts of active hydroxyl on water soluble starch surface favors various of modifications to achieve the ideal physical and chemical properties.In addition,water soluble starch is of rich resource and high safety.Therefore,this research extracted a kind of water soluble starch(SMSS)from sweet corn endosperm of su1 type as raw material to prepare nano-sized carrier particles for the transmission of functional ingredients.Firstly,SMSS was modified by octenyl succinic anhydride(OSA)as OS-SMSS whose properties were then explored.After modification,Zeta-potential of water soluble starch decreased to-44.4 mV,molecular weight and radius of gyration increased,while molecular density decreased.DS(Degree of Substitution)value was 5.0%.OS-SMSS showed spherical structure of 30~80 nm under transmission electron microscopy.OS-SMSS aqueous solution had good stability under wide range of pH value especially neutral pH.OS-SMSS could reduce the interfacial tension which was more appearant as the particle concentration increased.The contact angle of solid-oil-water phase reached nearly 90° while the particle desorption energy was maximized and the emulsion stability was improved as a result.Then,OS-SMSS particle was used in preparation of O/W emulsion.Rheology study revealed that emulsion stablized by OS-SMSS showed yield-pseudoplastic fluid properties.Emulsion with oil/water volume ratio of 1:10 had low viscosity,good fluidity,weak viscoelasticity which was close to Newtonian fluid.Emulsion with oil/water volume ratio of 1:1 showed sharply increased viscosity,decreased mobility,and stronger viscoelasticity.G' and G'' values kept stable as frequency increased.And G' value was greater than G'' value,tan ?<1,elucidating a kind of strong gel structure.It suggested that OS-SMSS may form viscoelastic networks between droplets as well as droplets and particles.With OS-SMSS concentration at 3% and 5%,oil and water volume ratio as 1:10,pH of water phase as 7.11,O/W emulsions encapsulating ?-carotene were prepared.The encapsulated rate of ?-carotene was 89.6% and 94.9% respectively.During storage,emulsion prepared by 5% OS-SMSS showed less increment in particle size and Zeta-potential.Retention rate of ?-carotene was higher and emusion stability was better.Further study was carried out on in vitro digestion of emulsion.Emulsion stablized by 3% and 5% OS-SMSS released significantly higher FFA(Free Fatty Acid)than control.The bioaccessibility of ?-carotene was 18.5% and 24.9% respectively,also higher than 2.6% of control.It elucidated that OS-SMSS based emulsion system could effectively promote the digestion of MCT oil phase and improve the bioaccessibility of ?-carotene.Finally,utilizing SMSS particle as the carrier,coenzyme Q10-SMSS and resveratrol-SMSS nanoparticles were prepared by cosolvent way of solid dispersion technology.The optimized preparation conditions of nanoparticles were nutrients and SMSS mass radio as 1:27 and 1:80 respectively for Q10 and resveratrol.The corresponding load rate was 1.0% and 1.4% respectively.The nanoparticles improved the water solubility of nutrients significantly.For 20 mg/mL nanoparticles in aqueous solution,the solubility of Q10 and resveratrol reached 188.8 ?g/mL and 274.2 ?g/mL respectively.FT-IR,DSC and XRD analysis of nanoparticles showed that the loaded nutrients existed in amorphous state.During storage,the light would accelerate the degradation of nutrients.So,reserving nanoparticles in solid form avoiding light could maximize retention rate of nutrients.Further research was carried out on simulated gastrointestinal dissolution of nanoparticles.In gastric juice,SMSS carrier only had mild hydrolysis.Releasing rate of coenzyme Q10 and resveratrol were 41.5% and 37.6% respectively.It suggested that nutrients mostly loaded in highly branched district near particle surface.In intestinal juice,SMSS was almost hydrolyzed completely.But nutrients occupied some binding sites between enzyme and branched chains of SMSS causing certain obstacles to the hydrolysis.Final releasing rate of coenzyme Q10 and resveratrol were 87.4% and 82.3% respectively which had been over 70% in the first 5 min of hydrolysis.It indicated that water soluble starch carrier could realize quick release of nutrients in the intestinal tract.