薏苡仁淀粉的理化性质

对酶法制备的薏苡仁淀粉的化学组成、淀粉颗粒形貌及其理化特性进行研究.结果表明:薏苡仁淀粉中淀粉、蛋白质、脂肪和灰分的含量(干基计)分别为99.615%、0.254%、0.022%和0.105%;薏苡仁淀粉的相对密度为1.376 g.mL-1,其颗粒形状呈圆形和多边形,具有清晰可见的偏光十字,均位于颗粒的中心位置,其X-射线衍射图谱结构属于C型;薏苡仁淀粉在常温下的溶解度较低,薏苡仁淀粉糊的糊化温度为67.0-71.6℃,透光率为39.6%,具有较强的冻融稳定性,凝沉速度较慢,强酸或碱性条件下可减缓其凝沉速度,而中性条件促进其回生;Brabender粘度曲线显示,薏苡仁淀粉糊的热稳定性低于玉米淀粉糊而高于马铃薯淀粉糊,冷粘度稳定性高于玉米淀粉糊和马铃薯淀粉糊.

The physicochemical properties of Coix seed starch

The chemical composition of the starch from Coix seed by enzymic method,the surface morphology of starch granules,and the physicochemical properties of the Coix seed starch pastes were systematically observed and studied.The results showed that the dry sample of Coix seed starch contains 99.619% starch,0.254% protein,0.022% fat and 0.105% ash.The relative density of Coix seed starch is 1.376 g·mL-1.The Coix seed starch granules are rotundity and polygon,and have apparent polarization cross lying in the center of the granules.The X-ray diffraction patterns of Coix seed starch granules and its structure belongs to C-type.Coix seed starch has a lower solubility under normal temperature.The gelatinization temperature of Coix seed starch is 67.0-71.6 ℃,the transmission rate of Coix seed starch paste is 39.6%.Coix seed starch paste has slower condensation speed which decreased under the acidic or alkaline environment,but its retrogradation rate is fastest at neutral condition.According to Brabender viscosity curve,the thermal stability of Coix seed starch paste is lower than corn and stronger than potato,the viscosity stability is the strongest.