Screening and Characterization of Sweet Potato Seeds for Promoting the Retrogradation of Maize Amylose

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.