促进玉米直链淀粉回生的甘薯淀粉晶种的筛选及表征
Screening and Characterization of Sweet Potato Seeds for Promoting the Retrogradation of Maize Amylose
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摘要: 通过向四次回生的玉米直链淀粉中添加草酸侵蚀的四次回生的甘薯淀粉、甘薯直链和甘薯支链淀粉晶种(质量分数:1%),研究甘薯淀粉晶种对玉米直链淀粉回生的影响。结果表明,甘薯淀粉晶种明显促进了玉米直链淀粉回生长晶,其中甘薯直链淀粉晶种使得玉米直链淀粉回生率达到59.5%,比不添加晶种提高了19.3%。可见吸收光谱研究表明,甘薯淀粉晶种及长晶后的玉米直链淀粉均保持了双螺旋结构。X-射线研究表明草酸侵蚀后甘薯淀粉、甘薯直链淀粉、甘薯支链淀粉均为A+B型。将其分别添加到玉米直链淀粉中并长晶后的样品,结构均为B型。DSC研究表明,甘薯支链淀粉晶种具有最高的吸热焓,说明其晶体含量最高。三种晶种分别促进玉米直链淀粉长晶后的结构较为相似,晶体含量也较相近。该研究为提高淀粉的回生率、研究回生淀粉结晶结构提供良好的技术支持。Abstract: The effect of sweet potato starch seed on the retrogradation of maize amylose was studied by adding the seeds of potato starch, sweet potato amylose and sweet potato amylopectin respectively (mass fraction:1%). The seeds were retrograded four times and treated by oxalic acid before added to maize amylose. The results showed that sweet potato starch seeds promoted the crystallization of maize amylose significantly. Among them, sweet potato amylose seed made the maize amylose retrogradation rate reach to 59.5%, which was 19.3% higher than that of seed free. Visible absorption spectrum studies showed that all the seeds and corn amylose were double helix structure. After treated by oxalic acid, as shown by X-ray, the crystalline structure of sweet potato starch, sweet potato amylose and sweet potato amylopectin was A+B type, while all the corn amylose promoted by seeds was B type. As shown by DSC, amylopectin had the highest endothermic enthalpy among the three kinds of seeds, therefore had the highest crystal content. The structure and crystal content of maize amylose treated by three kinds of seeds were similar. This paper provides a good technical support for improving the retrograded rate of starch and studying the crystalline structure of retrograde starch.