Study On Properties And Application Of Carboxymethyl Starch And Xanthan Gum Combinations

Carboxymethyl starch is an anionic starch ether,which can be widely used as an important new food additive in various fields of food.Although carboxymethyl starch has many good properties that the native starch lacks,but a single starch material is generally difficult to have all the ideal properties required for food preparation,such as the thermal viscosity stability of the solution formed by carboxymethyl starch is greatly reduced,and the weak mechanical resistance and thermal shear capacity,which limits the application of carboxymethyl starch.It was found that the combination of starch and hydrocolloid had good synergistic effect and food safety,and could better improve the shortcomings of starch.In this paper,carboxymethyl starch and xanthan gum were combined to study the characteristics of the combinations and the interaction between carboxymethyl starch and xanthan gum.The protection and release of the water-soluble active substance blueberry anthocyanins by carboxymethyl starch-xanthan gum combinations were investigated and the application of the combinations in different environmental responsive emulsions was studied for the transport of the lipopolysaccharide active substance Pterostilbene.The main research contents are as follows:In this paper,the rheology,texture and microstructure of carboxymethyl starch and xanthan gum combinations in different proportions were studied.The results showed that the combination of carboxymethyl starch and xanthan gum showed higher co-potency in apparent viscosity,dynamic modulus and texture.The addition of xanthan gum increased the value of shear stress,apparent viscosity,elastic modulus G′,viscosity modulus G′′,hardness,viscosity and mastication of the combinations,and enhanced the pseudoplasticity.Moreover,the effect was more significant with the increase of the ratio of xanthan gum in the combinations.Combined with microstructure,Fourier transform infrared spectroscopy and ¹³C solid-state NMR,carboxymethyl starch and xanthan gum formed a denser,smaller cavity and more uniform arrangement of starch network structure mainly through inter-molecular hydrogen bond force,and its gel strength is high,shear resistance is strong,has the ability to resist deformation.The carboxymethyl starch-Xanthan gum complex system was used as the carrier,and the water-soluble functional factors-blueberry anthocyanins were targeted to form the carboxymethyl starch-xanthan gel-blueberry anthocyanin self-assembly delivery system,so as to study the stability of blueberry anthocyanins and the release of blueberry anthocyanins in vitro.The results revealed that all the microcapsules presented high encapsulation efficiency.Fluorescence microscopy showed that anthocyanin distributed homogenously through combinations,and the microcapsules revealed red-purple color.Thermogravimetric analysis demonstrated that combinations working as wall materials increased the thermal stability of anthocyanin.The cross-linking interactions between the combinations and anthocyanin were confirmed by FTIR and ¹³C solid-state NMR.Microcapsules created with an combinations ratio of 30/1 provided superior antioxidant stability.Furthermore,the storage stability results showed that the stability of anthocyanin was increased to 76.11%after the30-day storage（37℃）through combinations.The in vitro release experiments revealed that the anthocyanin were majorly retained inside microcapsules in the stomach,and released in the intestine.Pickering emulsion was prepared by using carboxymethyl starch-xanthan gum combinations with different proportions as emulsifying stabilizer.Rheology,texture properties,emulsification index,NMR imaging,thermal stability and storage stability were studied.The results showed that after the addition of xanthan gum,the apparent viscosity,hardness,viscosity and mastication of the emulsion prepared by the combinations increased significantly,and the pseudoplasticity and thermal stability were enhanced,and the effect was more significant with the increase of the ratio of xanthan gum in the emulsion.Combined with low-field NMR and storage stability observation,the emulsion with uniform stability and long storage life can be obtained when the combination ratio of carboxymethyl starch and xanthan gum is 3:1 and 1:1.The effects of NaCl concentration and pH on the emulsion prepared by carboxymethyl starch-xanthan gum combinations were studied.Results showed that,with the increase of NaCl concentrations,the average droplet size and zeta potential of the emulsion decreased significantly and the conductivity increased.Rheological characterization revealed all the emulsions showed thixotropic properties.NaCl in the emulsion could increase the spatial steric resistance and the electrostatic repulsion between droplets,and the network structure of the emulsion was enhanced.Atomic force microscopy confirmed that NaCl caused the extension of the molecular chain of h,and the double helix structure of xanthan gum was intertwined with carboxymethyl star,forming a stable network structure.Low-field nuclear magnetic resonance imaging showed that the moisture distribution in the emulsion was the most uniform under the induction of NaCl at 0.3 M.Furthermore,After storage at 25℃ for 9days,the emulsion prepared by adding NaCl was uniformly distributed and no obvious stratification.The hydrogen bond force existed between the combinations and NaCl was confirmed by FTIR.As pH increased from 3 to 11,the droplet size of the emulsion increased and the absolute value of Zeta potential decreased.Besides,the consistency coefficient of the emulsion was reduced and the pseudoplasticity was weakened.The variation of backscattered light intensity of the emulsion at pH 3 was the smallest.The combination of carboxymethyl starch and xanthan gum formed a good network structure and inhibited the phase separation of emulsion.The color distribution of Low-field nuclear magnetic resonance imaging of emulsions at pH 3,5 and 7 was more uniform and had better storage stability at 25℃ for 9days.pH affected the aggregation of oil droplets.The Pickering emulsion stabilized by combinations was pH-responsive and could be used as an effective carrier for biologically active substances.The carboxymethyl starch-xanthan gum combinations was used as the emulsion carrier system to prepare pterostilbene emulsion.The results showed that the emulsion prepared by the combinations can be effectively embedded in pterostilbene.When the ratio of carboxymethyl starch and xanthan gum is 1:1,the encapsulation efficiency can reach 96.20%.The results of backscattered light experiment and storage stability study showed that pterostilbene emulsion prepared by combinations was uniform and stable,and there was no obvious phase separation or emulsion droplet coalescence.When the ratio of carboxymethyl starch and xanthan gum is 1:1,the storage retention rate of pterostilbene in the emulsion is the highest.The cumulative release amount of pterostilbene in simulated gastric juice was significantly lower than that in simulated intestinal juice.Therefore,the emulsion prepared by combinations can be used as a delivery system for functional food dietary supplements or medical products,and is helpful to develop a highly efficient and reliable release system for hydrophobic bioactive compounds.