双酶协同制备玉米慢消化淀粉及其性质研究

Preparation and Properties of Corn Slowly Digestible Starch with Dual-enzymes Treatment

以普通玉米淀粉为原料,利用β-淀粉酶和葡萄糖苷转移酶协同处理制备慢消化淀粉,并研究其理化性质。试验表明,原淀粉在β-淀粉酶加酶量为20 mL、反应时间为4 h,葡萄糖苷转移酶加酶量为20 mL、反应时间为12 h时,慢消化淀粉含量最高可达16.37%;所有经过双酶处理后的样品的淀粉-碘吸附结合物的最大吸收峰位置,随着慢消化淀粉含量的增加而偏移增大;差示扫描量热仪结果表明慢消化淀粉样品的糊化起始温度、峰值温度、终止温度、起始与终止温度差均有显著的升高,淀粉热稳定性增强,糊化变得困难;与玉米原淀粉A型结晶结构相比,所有样品的晶型消失,仅在2=19.8附近出现尖锐的衍射峰,2=13.1附近有一弥散峰;扫描电镜结果显示,酶解后的样品变成不规则碎片,不再具有原淀粉的颗粒结构。

The common corn starch was applied as raw material to prepare the slowly digestible starch （SDS） by using β-amylase and transglucosidase, and the physicochemical properties of the SDS were also investigated. The content of SDS was up to 16.37% with addition of 20 mL β-amylase and 20 mL transglucosidase by stirring for 4 h and 12 h, respectively. The position of maximum absorption peak of starch samples binding iodine shifted obviously with increasing SDS content. Analysis by differential scanning calorimeter showed that the onset melting temperatures, the peak temperatures, terminated temperatures and the temperature differences between beginning and ending of SDS were improved significantly and its thermal stabilities were enhanced, resulting in more difficulty for starches to gelatinize. Compared to the native corn starch displayed “A” typical diffraction pattern, no crystal structure was found for all samples modified by enzymes which represented sharp diffraction peaks at 2？=19.8° and diffuse diffraction peaks at 2？=13.1？. Scanning electron micrographs revealed that all enzyme-treated samples had more irregular fragments without granular structures as native starch.