交联羧甲基玉米淀粉的制备及理化特性研究

以羧甲基玉米淀粉为原料，环氧氯丙烷为交联改性剂，乙醇溶液为反应介质，通过二次正交旋转组合试验设计，合成了交联羧甲基玉米淀粉，得出交联改性的回归模型。研究了产品糊的透明度、膨胀度、冻融稳定性、吸附性能以及流变学特性。结果表明，交联改性最佳工艺参数为反应温度53.2℃、环氧氯丙烷用量0.23%(占淀粉干基)、反应时间64.6min、pH10，改性淀粉表观黏度可达10.51Pa·s，较玉米淀粉和羧甲基淀粉表观黏度分别提高了214.67% 和88.35%。交联羧甲基玉米淀粉糊透明度和膨胀度增大，稳定性以及吸附性增强。淀粉糊呈现非牛顿剪切稀化假塑性流体特征，常温下交联羧甲基玉米淀粉糊的流变学模型符合幂定律τ＝ 105.6γ0.3599(γ为剪切速率，τ 为切应力)，R2=0.9882；常温下吸附动力学模型符合Freundlich 等温式Q= 0.4152C0.9894(Q 为吸附容量，C 为铅离子的质量浓度)，R2=0.9846。

Preparation and Physico-chemical Properties of Cross-Linked Carboxymethyl Corn Starch

Cross-linked carboxymethyl corn starch was prepared from carboxymethyl starch with epichlorohydrin as a crosslinking agent in ethanol-water medium. A four-variable, five-level quadratic orthogonal rotation combination design was employed for maximizing apparent viscosity of modified corn starch, and a regression equation describing the relationship of it with four variables was established. The physico-chemical properties of cross-linked carboxymethyl corn starch paste including transparency, expansion, freeze thawing stability, adsorptivity and rheological properties were studied. A maximum apparent viscosity of cross-linked carboxymethyl corn starch of 10.51 Pa·s was obtained under the following conditions: epichlorohydrin amount 0.23%, reaction temperature 53.2 ℃, reaction time 64.6 min, and pH 10, which was increase by 214.67% and 88.35%, respectively, compared with native corn starch and carboxymethyl starch. Cross-linked carboxymethyl starch had significantly higher apparent viscosity, transparency, expansion, thermostability, adsorptivity and freeze thawing stability than native corn starch and carboxymethyl starch and its paste belonged to pseudoplastic fluid and displayed shear thinning characteristics. Under normal temperature, the rheological model obeyed the following law: τ= 105.6γ0.3599 (τ, viscosity; and γ, shearing velocity), R2 = 0.9882, and the adsorption kinetic model was in accordance with Freundlich adsorption isotherm: Q = 0.4152C0.9894 (Q, adsorption capacity; and C, Pb2+ concentration), R2 = 0.9846.