含水量对机械活化大米淀粉理化特性的影响

采用籼米、粳米和糯米三种类型大米淀粉为原料,研究淀粉含水量对机械活化大米淀粉理化特性的影响,得到利于机械活化的淀粉含水量范围,从而提高机械活化效果,缩短机械活化时间。研究表明,随着机械活化时间的延长,三种大米淀粉的糊化度、冷水溶解率、糊透明度和还原力均增大,而碘兰值(BV)均减小。籼米淀粉在含水量为6.02%时最易发生分子链断裂,粳米淀粉和糯米淀粉均在含水量为8.50%左右时最易断链。对糊化度和冷水溶解率而言,籼米淀粉以含水量为6.02%时最大,粳米淀粉和糯米淀粉以含水量为8.50%左右最大;对糊透明度而言,三种大米淀粉均在含水量为8.50%左右时最大;而对于还原力和BV而言,籼米淀粉含水量为3.50%时变化最快;对粳米淀粉和糯米淀粉均以含水量为6.00%左右时变化最快。由此可知,淀粉含水量对大米淀粉的机械活化具有一定影响,得到适宜的机械活化大米淀粉的含水量范围为6.00%~8.50%左右。

Influence of Moisture Content on the Physicochemical Properties of Mechanically Activated Rice Starch

In order to obtain a suitable moisture content of starch for mechanical activation and to improve the mechanical activation effect for reducing the duration of mechanical activation, the influence of the moisture content on the physicochemical properties of mechanically activated rice starch isolated from three rice cultivars was investigated. The results indicated that when the duration of mechanical activation was prolonged, the gelatinization degree, cold-water solubility, transparency, and reducing power of rice starch increased, while the blue value (BV) decreased. Indica rice starch was easily decomposed by mechanical force when the moisture content was 6.02%, while the moisture content of Japonica rice starch and glutinous rice starch was about 8.50%. In terms of the gelatinization degree and cold-water solubility, Indica rice starch reached the maximum value at a moisture content of 6.02%, while Japonica rice starch and glutinous rice starch reached the maximum at about 8.50%. For transparency, all three rice starches reached the maximum value at a moisture content of about 8.50%. Regarding the reducing power and the BV, Indica rice starch exhibited the most rapid change at a moisture content of 3.50%, while that of Japonica rice starch and glutinous rice starch was determined at about 6.00%. It was concluded that the moisture content had some influence on the mechanical activation of rice starch, and moisture contents of 6.00%~8.50% were determined as the optimum for mechanical activation.