Study On The Preparation, Properties Of Citrate Starch And Compound Modified Starch

Citrate Sweet Potato Starch (CSPS) was prepared by the method of dry heat, using sweet potato starch (SPS) as raw material and citric acid as esterification crosslink agent. The preparation process of the CSPS, physical and chemical properties and in vitro digestive were studied. Meanwhile, octenyl succinic anhydride (OSA) and acetic anhydride (AC) were used as double degeneration with the purpose of improving physical and chemical properties of citric starch. The content of RS of different types of starch modified by citric acid and OSA or AC was compared. Through above studies, we wanted to get modified starch with higher in the content of RS and good gelatinization properties designing to supply the selection basis for the toxicology studies and blood lipids regulating function.1. CSPS was prepared by the method of dry heat. Response Surface Design of Design-Expert V.8.0.5software optimized the DS of CSPS. Optimal preparation of the dry heat method was as follows:the pH value1.5, the reaction temperature148.2℃, reaction time6.45h, mass ratio of citric acid and starch0.59, we could get the DS0.301±0.004of CSPS through above reaction conditions, the reaction efficiency of citric acid and SPS was (38.5±0.4)%.The fitting relationship of DS and factors were as follows:DS=-2.691+(2.77E-01)X1+(3.33E-02)X2+(7.26E-02)X3+(1.25E-01)X4+(1.50E-04)X1X2-(3.50E-03)X1X3+(8.50E-02)X1X4-(6.25E-04)X2X3+(3.75E-03)X2X4+(5.00E-02)X3X4-(1.09E-01)X,2-(1.08E-04)X22+(4.17E-05)X32-(7.96E-01)X42(R2=0.9693) The degree of influence of factors for the CSPS was as follows:the mass ratio of citric acid and starch> temperature> reaction time> pH value.2. The studies on the physical and chemical properties of CSPS showed that:(1) The infrared spectroscopy of the CSPS and SPS showed that a new absorption peak at1739cm-1which is the characteristic peaks of the carbonyl vibration, indicating that the esterification reaction did occur;(2) CSPS occurred vary degrees of degradation, the average degree of polymerization decreased with the increases of DS of CSPS.(3)The in vitro digestion resistant properties of CSPS showed that the RS content gradually increased with the increases of DS of CSPS, the CSPS could not be digested when DS of CSPS reached a certain level;(4) The peak viscosity decreased with the increase of DS, the viscosity curve showed a smooth straight line, when reaching a certain degree of substitution;(5) The swelling degree of CSPS was higher in warm water than sweet potato starch, but lower in high temperature. The swelling degree of CSPS decreased as the DS increased;(6)The whiteness of CSPS increased with the increase of DS of CSPS to some extent, when the DS reaches a certain level, the whiteness reduced.3. The monotropic and composite modified starch made by OSA and AC, the conclusions as follows:(1)Both of the AC and OSA can increase the peak viscosity of sweet potato starch. OSA could improve the peak viscosity more than AC;(2)The RS content of OSA-SPS and AC-SPS were higher than SPS, but the AC could increased the RS contents more than OSA;(3)CSPS,CRS,CPS and CCS were modified by OSA or AC. Secondary degeneration could play a role under the certain DS of CS,the DS of CSPS was0.047,CRS(0.056),CPS(0.049),CCS(0.055),respectively. OSA and AC could improve the peak viscosity.(4)Compared different types of compound modified starch,the RS content of CCS-AC reached (37.54±2.17)%, the SDS content reached (17.56±1.39)%.