嗜冷普鲁兰酶制备玉米抗性淀粉工艺优化及其表征

以玉米淀粉为原料，采用嗜冷普鲁兰酶脱支处理和压热处理相结合的方式制备玉米抗性淀粉，考察了玉米淀粉乳质量分数、耐高温α-淀粉酶添加量、嗜冷普鲁兰酶添加量、嗜冷普鲁兰酶作用时间对抗性淀粉得率的影响，采用正交试验对压热-酶解法制备玉米抗性淀粉的工艺参数进行了优化。采用扫描电子显微镜、X-射线衍射和差示扫描量热仪对玉米抗性淀粉形貌、晶体结构、热特性进行了观察与分析。结果表明，制备玉米抗性淀粉的最佳工艺条件为：玉米淀粉乳质量分数18%、耐高温α-淀粉酶添加量7 U/g、嗜冷普鲁兰酶添加量10 U/g、嗜冷普鲁兰酶作用时间9 h。在最佳条件下，玉米抗性淀粉得率为16.84%。玉米淀粉经复合酶法处理后，抗性淀粉形成了致密的层状晶体结构，表面形态结构呈现出不同于玉米原淀粉A型晶体结构的V型晶体结构；玉米抗性淀粉的起始温度、峰值温度、终止温度和相变焓值分别为117.07、140.69、153.03 ℃和1 858.12 J/g，均高于玉米原淀粉。

Optimization of Preparation Process for Corn Resistant Starch with Psychrophilic Pullulanase and Analysis of Its Properties

In this research, corn resistant starch was produced by autoclaving treatment combined with psychrophilic
pullulanase hydrolysis, and starch slurry content, the amounts of heat α-amylase and psychrophilic pullulanase, and
psychrophilic pullulanase reaction time were optimized for the enhanced production of corn resistant starch through
orthogonal array experiments. Then, the crystal structure characterization and formation mechanisms of resistant starch
were investigated by using the scanning electron microscope (SEM), X-ray diffraction (XRD) and differential scanning
calorimeter (DSC). It was found that the optimum parameters for resistant starch preparation were as follows: corn
starch slurry concentration, 18%; thermostable alpha-amylase dosage, 7 U/g; psychrophilic-pullulanase dosage, 10 U/g; and
reaction time, 9 h. The yield of resistant starch was 16.84% under these conditions. The crystal structure of resistant starch
belonged to the V-type, which was different from that the A-type crystal structure of raw starch. Compared to raw starch,
the resistant starch showed higher phase onset temperature (117.07 ℃), peak temperature (140.69 ℃), end temperature
(153.03 ℃) and phase change enthalpy (1 858.12 J/g), respectively, resulting in better thermo stability.