Study On Structural And Functional Properties Of Sorghum Starches And Correlation Analysis

In order to explore the structural,physicochemical and functional properties of sorghum starches and the correlation among them,17 sorghum samples were selected for current study.Scanning electron microscope,x-ray diffraction,high performance anion exchange chromatography,swelling power and solubility determination,differential scanning calorimeter,rapid visco analyzer,in vitro digestion and other methods were employed.Correlation analysis was used to study the relationship among structural properties,physicochemical properties and functional properties of sorghum starches.The starch granules of sorghum appeared as irregular spherical or polygonal with different sizes.Some starch granules showed pores in the surface.Sorghum starches displayed a typical A-type diffraction pattern,with a crystallinity ranging from 17.32%to 29.67%,which decreased with amylose content increasing.The contents of fa,fb₁,fb₂ and fb₃ in amylopectin were16.48%to 19.42%,44.93%to 47.99%,14.00%to 15.84%and 18.87%to 22.68%,respectively.The swelling power and solubility of sorghum starch increased with increasing temperature,but are non-linear.At the same temperature,the swelling power decreased with the increase of amylose.Among the pasting properties,the amylose content was related to peak viscosity,cold paste viscosity,breakdown,and setback significantly,but not related to hot paste viscosity.The sorghum starch had a gelatinization enthalpy ranging from 12.71 to 16.88 J/g,and a retrogradation enthalpy ranging from 6.52 to 10.33 J/g.Except for the gelatinization temperature range,the remaining thermodynamic parameters of natural sorghum starch were higher than that of retrograded starch.The degree of retrogradation ranged between 47.01%and 69.73%.The gelatinization onset temperature,peak temperature,conclusion temperature,and gelatinization enthalpy were all related to the amylose content and the distribution of amylopectin chain length.