| Red adzuki beans are one of the traditional miscellaneous beans in China.They are rich in carbohydrates,proteins,minerals and water-soluble vitamins.They have high nutritional value.They are often used to process red azuki bean paste,red azuki bean soup,honey-stained red azuki beans and other foods.Contains sodium chloride and sucrose and other ingredients,these ingredients will cause the red adzuki bean properties to change in varying degrees.In this paper,three different varieties of red azuki beans(Dahongpao,Baoqinghong,Pearl Red)were taken as the research objects,and the influence of sodium chloride and sucrose on the starch properties and in vitro digestibility was studied.First,using three kinds of adzuki beans in Heilongjiang Province as raw materials,the process of extracting adzuki bean starch by alkali extraction was optimized.Through single factor and orthogonal experiments,the best process parameters of alkaline extraction were determined as follows:alkali concentration 0.3%,material-liquid ratio(1:4)g/mL,soaking time 3 h,soaking temperature 35?.Then use scanning electron microscope,polarized light microscope,laser particle size analyzer,X-ray diffractometer,Fourier infrared spectrometer,fast viscosity analyzer,differential scanning calorimeter and rheometer to compare their differences in properties.Observation with a scanning electron microscope(SEM)showed that most of the pearl red starch granules showed irregular ellipses with different sizes and a few surfaces were slightly raised;the surface of Baoqing red starch was smooth and most of them were similar Due to the regular oval shape,the surface is smooth;the granular shape of Dahongpao starch is infinitely close to a full spherical shape,and the surface is smooth.Polarized light microscope showed that the polarized cross of Dahongpao starch was clearer than the other two starches.The laser particle size analyzer showed that the highest volume average particle size of pearl red starch is 43.29 ?m,the lowest is Dahongpao starch 35.58 ?m;the highest surface area particle size of Baoqing red starch is 15.52 ?m,and the lowest pearl pearl red starch is 8.3?m.X-ray diffractometer(XRD)was used to study the crystal structure and relative crystallinity.The results showed that the three adzuki bean starches showed strong diffraction peaks at the diffraction angles 20 of 15°,17°,and 23°,all of which showed typical A Type crystal structure;the relative crystallinity ranges from 22.7%to 29.4%,of which the relative crystallinity of Dahongpao starch is higher.The results of Fourier transform infrared spectrometer of three kinds of adzuki bean starch show that the peak positions of the functional groups of pearl red,Baoqing red and Dahongpao starch are the same,but the absorption peak intensity of infrared spectra of the three kinds of adzuki bean starch is to a certain extent The intensity is different,the order of intensity is:pearl red starch>Baoqing red starch>Dahongpao starch;the gelatinization properties of three red adzuki bean starches determined by differential scanning calorimetry(DSC),the results show:gelatinization The starting temperature range is 59.75?62.92?,of which the starting temperature of Dahongpao starch is the highest and that of pearl red starch is the lowest.The enthalpy values of Dahongpao,Baoqing red and pearl red starch are 7.47 J/g and 6.55 J,respectively./g and 7.34 J/g;The RVA properties of the three adzuki bean starches showed that the peak viscosity of the three starches ranged from 8614 to 11461 cP,of which pearl red starch had the highest peak viscosity and Dahongpao starch had the lowest.In addition,the final viscosity range of the three starches is 6170?6863 cP,the final viscosity of the Dahongpao starch is the highest,and the pearl red starch is the lowest;the rheometer results show that the shear stress of the three adzuki bean starches increases with the shear rate.Large and increasing,with pseudoplastic fluid characteristics;and the shear viscosity of the three starches increases with the shear rate,the three curves flex to the shear stress axis to varying degrees,it can be judged that they are all non-Newtonian fluids,In line with the characteristics of starch in rheological properties.As the shear rate increases,the shear viscosity of the starch paste decreases.When the shear rate is 10 s-1,the viscosity decreases sharply.Among them,the decrease trend of the shear viscosity of the Dahongpao starch is the most obvious,showing a strong Shear thinning phenomenon,G 'and G " all increase with the increase of frequency,showing a typical weak gel dynamic rheology spectrum,among them,G'and G "of Dahongpao starch The lowest value.After adding 2%sodium chloride,the average particle size,peak viscosity,attenuation value,retrogradation value and gel strength of the three adzuki bean starches decreased;the settling rate,gelatinization start,peak and end temperatures,valleys and The final viscosity increases;while the addition of 10%sucrose reduces the average particle size,peak and valley viscosity of adzuki bean starch;the start,peak and end temperature,attenuation value,final viscosity and retrogradation value of starch increase,while the enthalpy changes and The gel strength did not change significantly.In the in vitro digestion experiment,after adding sodium chloride and sucrose,the content of RDS decreased,the content of SDS increased,and the content of RS increased;indicating that the addition of sodium chloride and sucrose will inhibit the digestion of starch,but because sodium chloride digests enzymes The resistance is higher than sucrose,so the effect on the hydrolysis properties of starch is significantly greater than sucrose.In summary,based on the multi-angle comparison of the starch properties of different varieties of adzuki beans,this experiment studied the effects of adding sodium chloride and sucrose on the properties and digestion characteristics of adzuki beans,and determined the sodium chloride And part of the reason why sucrose changes the structure structure of starch promotes the improvement of the functional characteristics of adzuki beans. |
PDF Full Text Request