Nano-starch has many characteristics, such as the small particle size, large specific surface area,nanometric size effects and nano enhancement.In this study, the corn nano-starch was prepared by a double screw extrusion with six cylinders and the morphology, crystalline property and rheological properties of nano-starch were also characterized.The results showed that the D50 particle size of corn nano-starch was reached to 225.8 nm when the dosage of glycerol was 20%, the dosage of glyoxal was 2.0% under the condition of screw speed was 160 r/min and the second to sixth cylinder temperature is 80, 100, 110, 115, 120 ℃, respectively.The structure of nano starch was integrity and its surface is smooth.The glyoxal reacted with the hydroxyl groups of starch to form the acetal compound and a new absorption peak was appeared in the FTIR spectra.Its TG spectra are similar to the original corn starch, and has the similar thermal stability with the corn starch.The XRD peak of nano-starch was weakened compared with the original corn starch and its crystallization area was obviously destroyed.Nano-starch paste is a pseudoplastic fluid with shear thinning properties as the original corn starch, and with the decrease of particle size of the nano starch, the transmittance of its paste increased.The corn nano-starch has broad application prospects in food processing, preservation and packaging due to its unique nano properties.%纳米淀粉具有粒径小、比表面积大,纳米小尺寸效应、纳米增强等特点,采用六节筒体的双螺杆挤压机制备玉米纳米淀粉,并对其进行表征.研究结果表明:当挤压机2~6区的腔体温度分别固定为80,100,110,115,120 ℃,甘油用量为20%,乙二醛用量为2.0%,螺杆转速为160 r/min时,所制得纳米淀粉的D50粒径最小,为225.8 nm;纳米淀粉结构完整、表面光滑,乙二醛与淀粉羟基反应生成了缩醛类化合物,红外谱图出现新的吸收峰;其热重分析曲线与原淀粉相似,热稳定性无明显变化;纳米淀粉的X射线衍射(XRD)峰型减弱,结晶区破坏明显;纳米淀粉糊液属假塑性流体,具有剪切稀化性质,随着纳米淀粉粒径的减小,糊液透光率逐渐增大.玉米纳米淀粉的独特纳米特性有望在食品加工、保鲜和食品包装等领域广泛应用.
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