Preparation Of Poly- Maltodextrin By Cross-linking And Its Properties

Poly-maltodextrin were synthesized by cross-linking with different DE values of maltodextrin, which were enzymatic hydrolysis products of corn starch, and the properties of maltodextrin, poly-maltodextrin were evaluated by modern analytical tools.The dextrose equivalent(DE) values of 35, 40, 45 maltodextrin were obtained by enzyme hydrolysis of corn starch. The molecular weight, physical and chemical characteristics, crystalline structure, surface characteristics of maltodextrin were evaluated. High performance liquid chromatography and multi-angle laser light-scattering and refractive index detection(HPLC-MALLS-RI) were used to characterize maltodextrin, it was found that the molecular weight of MD-35, MD-40, MD-45, respectively, were 31040, 12780, 2535. The hygroscopicities of MD-35, MD-40 and MD-45 gradually increased as the dextrose equivalent(DE) and relative humidity(RH) increased. The flow curves of maltodextrin well ?tted to the τ=kεn model, MD-35, MD-40 and MD-45 exhibited shear thinning behavior. The result of XRD showed that maltodextrin had no crystalline pattern. The analysis fo scanning electron microscope indicated that maltodextrin powders by spray-drying showed well formed, small, spherical in shape microparticles, presence of surface depression.The poly-maltodextrin were synthesized from the DE value of 35, 40, 45 maltodextrin, with sorbitol, citric acid under the condition of high temperature. The single factor experiments and Design-Expert software analysis results indicated that the suitable parameters for the preparation of poly-maltodextrin. The optimal parameters of PMD-35 were as follows: reaction temperature 190℃, reaction time 90 min, sorbitol amount of 12%, citric acid amount of 9%, and the content of poly-maltodextrin was 80.8%. The optimal parameters of PMD-40 were as follows: reaction temperature 185℃, reaction time 90 min, sorbitol amount of 12%, citric acid amount of 9%, and the content of poly-maltodextrin was 81.9%. The optimal parameters of PMD-45 were as follows: reaction temperature 170℃, reaction time 90 min, sorbitol amount of 12%, citric acid amount of 9%, and the content of poly-maltodextrin was 82.8%.Fourier infrared spectrum spectra of poly-maltodextrin showed some new absorption bands at 1731.29cm-1 assigned to ester bond carbonyl deformation vibration, these new absorptions suggest that poly-maltodextrin products were formed. It was found that there were some new peaks appearing at σ2.792 ppm, due to citric acid methylene signals belonging to protons of poly-maltodextrin in the 1H NMR spectrum, and there were some new peaks appearing at σ165.927 ppm, σ43.321 ppm, respectively, due to citric acid ester bond, methylene signals belonging to carbons of poly-maltodextrin in the 13 C NMR spectrum. The molecular weight, physical and chemical characteristics, crystalline structure, surface characteristics of poly-maltodextrin were evaluate. HPLC-MALLS-RI were used to characterize poly-maltodextrin, it was found that the molecular weight of PMD-35, PMD-40, PMD-45, respectively, were 188200, 106200, 25270. The result of transparency showed that the transparency of PMD-35, PMD-40, PMD-45, respectively were 73.23%, 83.27%, 88.41%. The hygroscopicities of PMD-35, PMD-40 and PMD-45 gradually increased as the dextrose equivalent(DE) of maltodextrin and relative humidity(RH) increased. The flow curves of poly-maltodextrin well ?tted to the τ=kεn model, PMD-35, PMD-40 and PMD-45 exhibited shear thinning behavior. The result of X-ray diffraction showed that poly-maltodextrin had no crystalline pattern. The scanning electron microscopy and atomic force microscope displayed that poly-maltodextrin powders by spray-drying showed well formed, spherical in shape microparticles, presence of surface depression, which were close to the maltodextrin.