水分对高静压处理不同类型淀粉微观结构的影响

摘要

利用高静压(HHP)作为物理变性方法处理糯玉米淀粉和木薯淀粉，考察水分含量对不同类型淀粉的糊化及重结晶的影响。用偏光显微镜、扫描电子显微镜观测 HHP 处理后淀粉颗粒的形态变化，利用激光粒度分析仪记录淀粉颗粒的粒度分布及变化规律，结合 X 射线衍射曲线及低场核磁共振图谱，分析淀粉颗粒内水分的结合方式及程度。结果表明：当粉水比(淀粉质量和水质量之比)为3/10~5/10时，在 HHP 处理下，两种淀粉均发生结晶解体和溶胀现象。糯玉米淀粉的重结晶程度顺序为4/10粉水比>3/10粉水比>5/10粉水比；木薯淀粉颗粒结晶结构完全消失，结晶破坏的程度是3/10粉水比>4/10粉水比>5/10粉水比。随着水分含量增大，糯玉米淀粉及木薯淀粉的粒度逐渐增大。干燥后淀粉中的水分主要以结合水的形式存在，且水分参与结晶结构的形成。%Waxy maize and tapioca starch with different starch-water ratios were treated by high hydro-static pressure (HHP)- a physical modification method - under 600 MPa.The effects of moisture content on gelatinization and retrogradation properties of the two kinds of starch were investigated. The appearance and particle size of granules were studied by micro-polariscopy,scanning electron microscopy and laser diffraction instrument.Combining the X-ray diffraction and nuclear magnetic resonance (NMR)spectrum,the change from crystal to non-crystal was confirmed again,and the water status in starch was studied,too.The results indicate that the crystalline structure destroying and gelatinization happen when the starch-water ratio was between 3/10 and 5/10.The degree of retrogradation for waxy maize starch was 4/10>3/10>5/10 (starch-water ratio),whereas the degree of crystalline structure destroying for tapioca starch was 3/10>4/10>5/10 (starch-water ratio).The diameter of waxy maize and tapioca starch granules increased significantly with moisture content. Water was kept within the crystalline lamella in the form of bond water.