Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
Carbohydr Polym. 2013 Oct 15;98(1):295-301. doi: 10.1016/j.carbpol.2013.05.085. Epub 2013 Jun 6.
Waxy maize starch in an aqueous sulfuric acid solution (3.16 M, 14.7% solids) was hydrolyzed for 2-6 days, either isothermally at 40 °C or 4 °C, or at cycled temperatures of 4 and 40 °C (1 day each). The starch hydrolyzates were recovered as precipitates after centrifuging the dispersion (10,000 rpm, 10 min). The yield of starch hydrolyzates depended on the hydrolysis temperature and time, which varied from 6.8% to 78%. The starch hydrolyzed at 40 °C or 4/40 °C exhibited increased crystallinity determined by X-ray diffraction analysis, but melted in broader temperature range (from 60 °C to 110 °C). However, the starch hydrolyzed at 4 °C displayed the crystallinity and melting endotherm similar to those of native starch. The starch hydrolyzates recovered by centrifugation were re-dispersed in water (15% solids), and the dispersion was treated by an ultrasonic treatment (60% amplitude, 3min). The ultrasonication effectively fragmented the starch hydrolyzates to nanoparticles. The hydrolyzates obtained after 6 days of hydrolysis were more resistant to the ultrasonication than those after 2 or 4 days, regardless of hydrolysis temperatures. The starch nanoparticles could be prepared with high yield (78%) and crystallinity by 4 °C hydrolysis for 6 days followed by ultrasonication. Scanning electron microscopy revealed that the starch nanoparticles had globular shapes with diameters ranging from 50 to 90 nm.
将玉米淀粉(waxy maize starch)在 3.16M（14.7%固含量）的硫酸水溶液中进行水解，水解时间为 2-6 天，条件为 40°C 或 4°C 恒温，或在 4°C 和 40°C 之间循环（每天各 1 天）。将分散体（10,000rpm，10min）离心后，将淀粉水解产物作为沉淀物回收。淀粉水解产物的产率取决于水解温度和时间，从 6.8%到 78%不等。在 40°C 或 4/40°C 下水解的淀粉表现出更高的结晶度，这是通过 X 射线衍射分析确定的，但在更宽的温度范围内（60°C 至 110°C）熔融。然而，在 4°C 下水解的淀粉显示出与天然淀粉相似的结晶度和熔融热焓。通过离心回收的淀粉水解产物重新分散在水中（15%固含量），并通过超声处理（60%幅度，3min）对分散体进行处理。超声处理有效地将淀粉水解产物碎化成纳米颗粒。与 2 天或 4 天的水解相比，在 6 天的水解后获得的水解产物，无论水解温度如何，在超声处理下都具有更高的稳定性。通过在 4°C 下水解 6 天然后进行超声处理，可以以高产率（78%）和结晶度制备淀粉纳米颗粒。扫描电子显微镜显示，淀粉纳米颗粒呈球形，直径范围为 50 至 90nm。
