低温挤出-多酶协同降解脱胚玉米中淀粉的机理

Mechanism of starch degradation of corn grist degermed by extruded at low-temperature and multienzyme synergistic degradation

为了改变目前挤出酶解谷物淀粉仅添加一种酶制剂(α-淀粉酶),只能降解淀粉的α-1,4糖苷键,不能降解支链淀粉的α-1,6糖苷键,限制淀粉转化成葡萄糖的收率进一步提高的现状,该文应用低温(≤80℃)挤出-多酶(α-淀粉酶、糖化酶、普鲁兰酶)协同降解技术,制备挤出过程中物料的石蜡显微制片,观察脱胚玉米经低温挤出-多酶协同降解处理后,细胞壁、细胞中的淀粉颗粒和蛋白质颗粒的分布状况以及淀粉含量、糊化度、可溶性糖含量的变化。结果表明:在挤出过程中,淀粉发生糊化和降解,表观淀粉质量分数减少,从81.50%减少到74.40%,可溶性糖质量分数增加,从1.07%增加到2.26%,挤出过程中加入酶制剂后这种变化更加明显。添加单一α-淀粉酶表观淀粉质量分数从79.72%减少到69.16%,可溶性糖质量分数从6.54%增加到7.90%。添加α-淀粉酶和糖化酶表观淀粉质量分数从81.42%减少到72.45%,可溶性糖质量分数从11.65%增加到14.71%。添加α-淀粉酶和普鲁兰酶表观淀粉质量分数从81.31%减少到70.31%,可溶性糖质量分数从6.74%增加到8.29%。添加α-淀粉酶、糖化酶、普鲁兰酶3种酶时淀粉质量分数从81.06%减少到69.05%,可溶性糖质量分数从11.25%增加到16.35%。因此,3种酶(α-淀粉酶、糖化酶、普鲁兰酶)协同作用对淀粉降解以及可溶性糖含量的增加作用效果最好。显微切片的分析结果表明:添加3种酶制剂(α-淀粉酶+糖化酶+普鲁兰酶)的切片,细胞结构中淀粉颗粒被降解破坏的程度大于添加1种(耐高温α-淀粉酶)、2种(α-淀粉酶+糖化酶,或者α-淀粉酶+普鲁兰酶)酶制剂的细胞结构中淀粉颗粒被降解破坏的程度。低温挤出-多酶协同降解后,脱胚玉米挤出物的总淀粉含量降低、可溶性糖含量增加,糊化度增加。试验表明:添加3种酶制剂协同降解脱胚玉米中淀粉的作用效果优于添加1种酶制剂或2种酶制剂的淀粉降解效果,为进一步提高淀粉转化成葡萄糖的收率提供科学依据。

In order to improve the conversion rate of starch to glucose,an enzyme(α-amylase)was added to amylopectin by changing theα-1,6-glycoside bond in amylopectin by extrusion enzymatic hydrolysis technology,and the microstructure of paraffin section was introduced.Low temperature(≤80℃)extrusion,multi-enzyme(α-amylase,glucoamylase,pullulanase)synergistic degumming preparation.The distribution of protein granules and starch granules and the main physicochemical indexes of starch degradation in cells were observed.The results showed that starch content decreased from 81.50%to 74.40%and soluble sugar content increased from 1.07%to 2.26%during extrusion.The change of enzymatic extrusion process was more obvious.By addingα-amylase,starch content decreased from 79.72%to 69.16%,soluble sugar content increased from 6.54%to 7.90%.By addingα-amylase and glucoamylase,the starch content decreased from 81.42%to 72.45%,and the soluble sugar content increased from 11.65%to 14.71%.By addingα-amylase and pullulanase,starch content decreased from 81.31%to 70.31%,soluble sugar content increased from 6.74%to 8.29%.By addingα-amylase,glucoamylase and pullulanase,the starch content decreased from 81.06%to 69.05%,and the soluble sugar content increased from 11.25%to 16.35%.The results of microsection showed that the degradation degree of starch granules in the three enzymes was better than that of one(α-amylase)or two enzymes(α-amylase,glucoamylase orα-amylase,pullulanase).The results showed that starch content decreased,soluble sugar content increased and gelatinization degree increased in degummed maize by low temperature enzymatic extrusion.At the same time,the effect of adding three enzymes(α-amylase,glucoamylase and pullulanase)on starch degradation was better than adding one enzyme(α-amylase)or two enzymes(α-amylase,glucose-amylase orα-amylase,pullulanase).These results provide useful data for improving starch utilization.