Study On Structure And Properties Of Different Varieties Yam Starches

The dry yam starch content reaches as high as 60%,and the structure and properties of starch are of great relevance to starch procession.We extracted yam starch from six different varieties here,and the molecular structures and properties of different yam starch was studied before and after the heat-moisture treatment.The main results were listed as follows:1.In this paper,the researches on the structure of yam starch shows that the average granules size of yam starch are 18.73 to 25.27 ?m,and several varieties exhibit cracks on the granule surface.All yam starch has obvious polarization cross.The crystal structure of the starch granule are type B and type C.The C1 region of the C13 spectrum of Guihuai No.8,Tiegun yam and Purper yam are of great difference to other three species.The Iodine absorpion of Guihuai No.7 is significantly higher than the others.Purper yam shows the best digestion resistibility while Guihuai No.7 is the weakest.There was a significant negative correlation between the contents of amylose and water leaching rate.2.The molecular structures and properties of starch from six varieties were analysed with review of literatures.It is showed that the yam from Guihuai No.7,Purper yam and Guihuai No.8 had better processability than others and which are suited for manufacturing into cold starch noodle,adhesive and edible films,respectively.3.After heat-moisture treatment,the structure and properties of different varieties of yam starch were studied.All yam starch still has obvious polarization cross after the heat-moisture treatment,and it did not change the integrity of the structure and crystal types.But the Iodine absorption,peak and valley viscosity and attenuation values were significantly decreased while pasting temperature increased.After the heat-moisture treatment,the water leaching rate of Purper yam decreased while the starch solubility of Loudi yam inceased,and the Guihuai No.7 and Tiegun yam showed the lower swelling power and higher digestion resistibility.This paper studied the structure and properties of different varieties of yam starch,and the influences of heat-moisture treatment on structure and properties of yam starch systematically.And it can provide a theoretical basis for the yam starch products processing and yam varieties breeding.