加酶挤压对小麦淀粉结构和理化性质的影响

本文旨在探究加酶挤压对小麦淀粉结构和理化性质的影响。分别设置浓度梯度为0%、0.1%、0.2%、0.5%、1%、2%的α-淀粉酶-小麦淀粉混合物样品，挤压处理后，利用扫描电镜（SEM）、差示扫描量热仪（DSC）、X-射线衍射仪（XRD）、快速粘度仪（RVA）等分析淀粉结构与理化性质的变化。结果表明:各处理组的堆积密度无显著差异（P>0.05）；吸水指数与加酶量呈负相关，水合指数与加酶量呈正相关；挤压后淀粉糊化度均大幅度提高，接近完全糊化；挤压后淀粉的颗粒结构被完全破坏且加酶使得淀粉颗粒粒径更小；加酶挤压处理后相对结晶度降低，从原淀粉的17.52%降至10.29%（酶浓度2%）；挤压处理后小麦淀粉的糊化焓均显著下降（P<0.05），挤压淀粉样品焓值最低，仅为0.24 J/g，加酶挤压淀粉的焓值高于挤压淀粉，随着加酶量的增加，淀粉的焓值上升至2.5 J/g左右；RVA曲线可明显看出处理组的粘度远低于原淀粉粘度，且加酶挤压样品粘度低于不加酶挤压粘度。本文探明了加酶挤压对淀粉结构和理化性质的作用规律，可为加酶挤压技术在淀粉基食品领域的应用提供理论指导。

Effect of Enzyme Extrusion on Structure and Physicochemical Properties of Wheat Starch

This study aimed to investigate the effects of enzyme extrusion on the structural and physicochemical properties of wheat starch. The mixture of α-amylase (0%, 0.1%, 0.2%, 0.5%, 1% and 2%) and wheat starch were prepared and then extruded. After extrusion, the structural and physiochemical properties of wheat starch were analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), and rapid viscosity analyzer (RVA). The results showed that no significant difference in bulk density were observed among all treatments (P>0.05). With the increase of enzyme concentration, the water absorption index was decreased, and the hydration index was gradually increased. The gelatinization degree of starch was largely increased after extrusion, which indicated that the starch was almost completely gelatinized. SEM images suggested that the structure of starch granules was completely destroyed and the more extensive destruction was observed with the addition of enzyme. XRD patterns indicated that the relative crystallinity decreased from 17.52% of the native starch to 10.29% of the extruded sample with 2% enzyme. DSC results showed that the gelatinization enthalpy of wheat starch decreased significantly after extrusion (P<0.05). The lowest enthalpy was 0.24 J/g for extruded sample without α-amylase, while the enthalpy increased to about 2.5 J/g with the addition of α-amylase to 2%. This study explored the mechanism underlying the effect of enzyme extrusion on the structural and physicochemical properties of starch, which contributes to providing theoretical guides for the applications of enzyme extrusion in starch-based foods.