Department of Food Science, Old Agricultural Building (Building 46), University of Pretoria, Lynwood Road, Private bag X20 Hatfield, 0028 Pretoria, South Africa.
DST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa.
Carbohydr Polym. 2017 Jul 15;168:86-93. doi: 10.1016/j.carbpol.2017.03.067. Epub 2017 Mar 22.
Nanoparticles were isolated from tef and maize starch modified with added stearic acid after pasting at 90°C for 130min. This was followed by thermo-stable alpha-amylase hydrolysis of the paste. The resultant residues were then characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic laser scattering particle size distribution (DLPSD), atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). XRD and DSC showed that the isolated residues consisted of amylose-lipid complexes. These complexes were type II with melting temperature above 104°C. DLPSD, AFM and HRTEM showed that the isolated tef and maize starch residues consisted of nanoparticles which became more distinct with increased hydrolysis time. The isolated tef and maize nanoparticles had distinct particles of about 3-10nm and 2.4-6.7nm, respectively and the yield was about 24-30%. The results demonstrated that distinct (physically separate) nanoparticles of less than 10nm can be isolated after formation during pasting of tef and maize starch with stearic acid. The production and isolation of the nanoparticles uses green chemistry principles and these nanoparticles can be used in food and non-food systems as nanofillers.
纳米颗粒是从添加了硬脂酸的埃塞俄比亚画眉草和玉米淀粉中分离出来的，这些淀粉在 90°C 下糊化 130min 后进行了改性。然后对糊化后的淀粉进行热稳定的α-淀粉酶水解。利用 X 射线衍射（XRD）、差示扫描量热法（DSC）、动态激光散射粒度分布（DLPSD）、原子力显微镜（AFM）和高分辨率透射电子显微镜（HRTEM）对所得残留物进行了表征。XRD 和 DSC 表明，分离出的残留物由直链淀粉-脂质复合物组成。这些复合物为 II 型，熔点高于 104°C。DLPSD、AFM 和 HRTEM 表明，分离出的埃塞俄比亚画眉草和玉米淀粉残留物由纳米颗粒组成，随着水解时间的增加，这些纳米颗粒变得更加明显。分离出的埃塞俄比亚画眉草和玉米纳米颗粒的粒径约为 3-10nm 和 2.4-6.7nm，分别为 24-30%。结果表明，在硬脂酸存在下，埃塞俄比亚画眉草和玉米淀粉糊化过程中形成的纳米颗粒可以通过物理分离的方法分离出明显的（物理分离的）小于 10nm 的纳米颗粒。这些纳米颗粒的生产和分离采用了绿色化学原理，可作为纳米填料用于食品和非食品体系。
