Preparation And Properties Of Potato Starch Composite Gel

In this study,soy protein isolate（SPI）and maltose were used as raw materials to prepare soy protein-maltose graft copolymers,and the structural and functional properties of the sugar graft copolymers were analyzed by various technical means to investigate the influence of maltose on the structural and functional properties of soy protein isolate sugar graft copolymers.Potato starch and soybean isolate protein sugar graft copolymer were used as the basic raw materials,and potato starch composite gel with excellent performance was prepared by adding three structural modifiers of gum Arabic,guar gum and chitosan,and the structure and properties of potato starch composite gel were characterized.The results were as follows.1.To optimize the conditions of the sugar grafting reaction between soybean isolate protein and maltose,the effect of sugar grafting reaction time,temperature,soybean isolate protein to maltose mass ratio and p H on the grafting reaction was investigated with the degree of grafting（DG）as the index.The results showed that the optimal reaction conditions for the maltose and SPI sugar grafting reaction were:temperature 70℃,p H 9,soybean protein-maltose（mass ratio）1:4,and time 3 h.2.The structural and functional properties of sugar graft copolymers were investigated using soybean isolate protein（SPI）and maltose as the main raw materials.The results showed that the thermal stability（DSC）of the sugar graft copolymers improved significantly with the introduction of maltose molecules compared with SPI and increased with the increase of grafting degree;the surface hydrophobicity（H₀）and oil-holding property decreased gradually with the increase of grafting degree;the surface structure of the sugar graft copolymers was looser with more unevenly raised flakes and blocky surface structure forms;the Fourier infrared spectra（FT-IR）spectroscopy（FT-IR）showed that the grafting reaction caused-OH radical stretching vibration,and the absorption peak of-OH gradually increased with the increase of grafting degree.The results of polyacrylamide gel electrophoresis（SDS-PAGE）showed that the color of the subunit bands gradually became lighter with the gradual increase of the grafting degree of the graft copolymer,and the diffusion bands with higher molecular weight appeared on the top of the isolate,indicating that the covalent condensation reaction between soybean isolate and maltose occurred.3.Potato starch and sugar graft copolymer were used as the basic raw materials to investigate the formation mechanism of different hydrophilic colloids on potato starch gels.The structural characterization was performed by FT-IR,differential scanning calorimetry（DSC）,X-ray diffraction（XRD）and scanning electron microscopy（SEM）techniques.The results showed that the potato starch composite gel did not produce new absorption peaks,no new chemical bonds were generated,and the surface structure of the composite gel became rough;the crystallinity and the enthalpy of pasting（ΔH）of the potato starch composite gel were reduced,and the volume average particle size increased.The hardness of the composite gel increased by 35.96%and 41.73%after the addition of gum Arabic and guar gum,respectively,and decreased by 47.09%after the addition of chitosan;the peak viscosity of potato starch composite gel increased after the addition of guar gum and chitosan,and decreased after the addition of gum Arabic.