高直链玉米Ⅲ型抗性淀粉制备及其结构和特性

Preparation,Structure and Properties of High-Amylose Maize TypeⅢResistant Starch

以高直链玉米淀粉G50和G70为原料,经酸解、糊化、脱支和重结晶步骤获得Ⅲ型抗性淀粉,通过退火与压热处理以进一步提升淀粉的抗性比例。采用扫描电子显微镜、X射线衍射、差示扫描量热、快速黏度分析等方法,研究淀粉颗粒形貌、结晶结构、热特性及糊化特性,利用Englyst法测试淀粉消化特性。结果表明:高直链玉米淀粉G50和G70酸解后的得率分别为77.9%和84.5%,重结晶后的得率降为54.4%和70.2%。原G50和G70改性后,淀粉颗粒形貌被破坏,形成大小不等、颗粒形貌不规则的团聚体;淀粉结晶型由B+V型转变为A+V型,且结晶度升高;淀粉糊化温度升高,且加热过程中黏度几乎消失。溶解与膨胀特性结果表明,经酸解、糊化、脱支和老化处理后原G50和G70的溶解性显著升高,退火和压热处理后降低了Ⅲ型抗性淀粉的溶解性和膨胀度。体外消化特性分析表明,改性后的G50和G70具备更强的抗消化性能,抗性淀粉含量最高可达80.5%(G70-RS3-压热20%)。本研究的改性处理能有效提高高直链玉米淀粉G50和G70中抗性淀粉含量,同时抗性淀粉含量与结晶度和糊化温度呈显著正相关。

Using high-amylose maize starch G50 and G70 as raw material, type Ⅲ resistant starch was obtained by successive steps of acid hydrolysis, pasting, debranching and recrystallization, and annealing and autoclaving treatments were used to improve the yield of resistant starch. Scanning electron microscopy(SEM), X-ray diffraction(XRD), differential scanning calorimetry(DSC), rapid viscosity analysis(RVA) were used to evaluate the morphology, crystalline structure, thermal properties and pasting properties of starch granules, and the digestion properties of starch were tested by the Englyst method. The results showed that the yields of type III resistant starch from high-amylose maize starch G50 and G70 after acid hydrolysis were 77.9% and 84.5%, respectively, and were reduced to 54.4% and 70.2% after recrystallization, respectively. For G50 and G70, the morphology of starch granules was destroyed after modification, and aggregates with different sizes and irregular shapes were formed. The crystalline type of starch changed from B + V to A + V, and the crystallinity increased. The pasting temperature of starch increased, and the viscosity almost disappeared after heating. The solubility of G50 and G70 significantly increased after acid hydrolysis, pasting, debranching and recrystallization, while the solubility and swelling power of type Ⅲ resistant starch decreased after annealing and autoclaving treatments. In vitro digestion tests showed that the modified G50 and G70 had stronger resistance to digestion than the raw ones, and the resistant starch content of G70-derived type III resistant starch autoclaved after addition of 20% water was the highest(80.5%). In conclusion, the modification treatment can effectively increase the content of resistant starch in high-amylose maize starch G50 and G70, and the content of resistant starch is significantly positively correlated with the crystallinity and pasting temperature.