湿热交联甘薯抗性淀粉的制备及理化性质研究

Preparation and physicochemical properties of cross-linked sweet potato resistant starch with heat-moisture treatment

以甘薯淀粉为原料,采用湿热交联协同处理,制备高含量抗性淀粉,探究最佳工艺条件并研究了其理化性质。结果表明,当交联剂质量分数为10%、pH11.5、水分20%及温度120℃时,制备的抗性淀粉质量分数达72.45%,结合磷质量分数为0.39%。通过31 P NMR检测,RS质量分数为72.45%产物中含有磷酸二淀粉酯(DSMP),而没有发现磷酸单淀粉酯(MSMP)。扫描电镜和偏光显微镜观测结果表明:在高水分下进行交联反应,淀粉颗粒易受水汽和热能的影响而部分糊化,表面发生部分破裂,从而影响淀粉的抗酶解性。X-射线衍射图谱显示,甘薯抗性淀粉的晶型仍为C型,但相对结晶度有稍许变化。糊化温度随水分增加而升高,糊化焓值则明显降低。

The sweet potato starch was applied as raw material to prepare high content resistant starch under heat-moisture cooperating with cross-linking treatment and the optimal conditions and the physicochemical properties of cross-linked sweet potato resistant starches were investigated. A maximum RS content （72.45 %） and combined phosphorus（0.39 %） were obtained after 10% STMP/STPP at 120℃ and pH11.5 with a 20% moisture level. The 31 p NMR spectroscopy of RS 72.45% indicated the presence of DSMP, but MSMP was not detected. SEM and polarization microscope images showed that starch granules were susceptible to water vapor and thermal energy and part of gelatinization occurred under high moisture content which resulted in part of surface erosion and affected resistance to enzymatic hydrolysis of starch. X-ray diffraction patterns revealed resistant starches remained C-type, while the relative crystallinity had little changes. Gelatinization temperature of resistant starches increased with the moisture content, while gelatinization enthalpy apparently decreased.