超声-微波协同酶法制备芸豆抗性淀粉工艺优化及结构分析

探究超声-微波协同酶法制备芸豆抗性淀粉的最佳工艺条件及其物理结构特性。以紫花芸豆为试验材料,利用超声-微波协同酶法制备RS3型抗性淀粉,考察不同水平时淀粉悬浮液质量分数、超声时间、普鲁兰酶添加量和微波功率对抗性淀粉得率的影响,同时做响应面优化试验;通过扫描电镜、红外光谱、凝胶渗透色谱仪等方法分析芸豆淀粉及抗性淀粉的结构特性。结果表明:淀粉悬浮液质量分数16%、普鲁兰酶添加量12.5 ASPU/g(干基)、微波功率300 W、超声-微波协同处理20 min时,芸豆抗性淀粉得率最高为(24.37±0.41)%。与原淀粉相比,芸豆抗性淀粉颗粒破损,呈形状大小各异的块状碎石结构;抗性淀粉未出现新的特征吸收峰;处理后的芸豆抗性淀粉平均聚合度降低,多分散系数降低。超声-微波协同酶解法可提高芸豆抗性淀粉得率,抗性淀粉形成过程中淀粉官能团没有变化,其余结构特性改变。

Process Optimization and Structure Analysis of Kidney Bean Resistant Starch by Ultrasound-Microwave Synergistic Enzymatic Method

The optimum conditions for the preparation of kidney bean resistant starch by ultrasonic-microwave synergistic enzymatic method and the structural characteristics of kidney bean resistant starch were investigated.Purple round kidney bean starch was used as experimental material,and RS3-type resistant starch was prepared by ultrasonic-microwave and pullulan enzymatic hydrolysis method.The effects of different levels of starch suspension mass fraction,ultrasonic time,pullulanase addition and microwave power on the yield of resistant starch were investigated,and the response conditions were used to optimize the process conditions,and the structures of kidney bean starch and resistant starch were analyzed by gel permeation chromatography,scanning electron microscopy and infrared spectroscopy characteristic.The results showed that the highest yield of the resistant starch of alfalfa was(24.37±0.41)%when the mass fraction of starch suspension was 16%,the amount of pullulanase was 12.5 ASPU/g(dry basis),the microwave power was 300 W,and the ultrasonic-microwave synergistic treatment for 20 min.Compared with the original starch,the resistant starch granules of kidney bean were broken and showed different shapes and sizes like a block of gravel structure.There was no new characteristic absorption peak of resistant starch.The average polymerization degree of resistant starch in kidney bean was decreased after treatment,the weight average and number average molecular weight increased,and the polydispersity coefficient decreased.Ultrasound-microwave synergistic enzymatic hydrolysis could increase the yield of resistant starch in kidney bean.The starch functional group unchanged during the formation of resistant starch,and the other structural characteristics changed.