Study On Composite Modified Propreation Of Slowly Digestible Starch

This article firstly determinate the slowly digestible starch content in deferentsources of starch, and finally selected the corn starch as the raw material. Theinnovation of this subject was on the existing research results, enzymatic debranch thestarch method and hydrothermal method to preparation of slowly digestible starch, andthis article mainly study on ultrasonic assisted enzymatic method to preparation ofslowly digestible starch and microwave assisted hydrothermal method to preparation ofslowly digestible starch research, as well as analysis the structure and the properties ofthe slowly digestible starch.First of all, the atricle improved the method of determinate the slowly digestiblestarch content on base of the current Guraya method and the Englyst method, examinethe effect of four factors on SDS content determination method, the four factors arepancreatic amylase, saccharifying enzyme addition, pH and the amount of starch, at thesame time, an orthogonal optimization test were taken and the optimal method ofdetermination the content of SDS were: taking200mg starch samples into a test tube,add15mL5.2pH0.2mol/mL sodium acetate buffer solution, after mixing with10mLof porcine α—amylase (300U/mL) and saccharifying enzyme (25U/mL), constantwater temperature placed at37℃, response to20min and120min after glucosereagent kit for determination of the resulting glucose content, calculated the content ofSDS according to the different value.In the process of ultrasonic assisted enzymaticpreparation of slowly digestible starch by single factor experiments to research theultrasonic power, reaction time, temperature, starch milk concentration, enzyme dosageof five factors on the yield of slowly digestible starch, and through orthogonal testobtained the best condition of ultrasonic assisted enzymatic preparation of slowlydigestible starch: ultrasonic power was300W, pullulanase14%, the reaction time was40min, the reaction temperature was40℃,and under this condition three timesrepetitive were tested, SDS yield was43.14%. In process of microwave assistedhydrothermal to preparation of slowly digestible starch, through the single factorexperiment research on four factors of microwave power, reaction time, temperature, moisture content and through orthogonal test obtained the best condition of themicrowave assisted hydrothermal to preparation of slowly digestible starch: microwavepower was300W, the reaction time was25min, the reaction temperature of50℃, watercontent of70%(dry basis), cold storage temperature was4℃, storage time was18hand the drying temperature was60℃, under these conditions the slowly digestiblestarch yield could reach a maximum of34.83%.The starch sample structure analysis on the use of the DSC and synchrotronradiation analysis means. DSC results showed that the microwave treatment topreparation of SDS samples and ultrasound assisted enzymatic preparation of SDSsample, the structure become more compact, with the initial gelatinization temperature,microwave and ultrasonic enzymatic preparation of SDS samples to the crystallizationzone were also become deranged. The synchrotron radiation test result show that themicrowave method and ultrasonic enzymatic treatment on starch samples of crystallineand amorphous region is seriously disturbed, especially to the crystallization zonedamage more serious, however, the amorphous region is more closely and the crystalof slowly digestible starch were more perfect.On the properties of SDS samples, the analysis results show that: the preparedSDS from common corn starch, the peak of starch paste viscosity become slightly,while the lowest viscosity were increased, the peak time also had a certain delayed,attenuation value is substantially smaller, starch paste transparency, retrogradation andfreeze-thaw stability is poorer.