2001 Volume 48 Issue 3 Pages 176-181
When tapioca starch was cooked rapidly with a dilute crude extract of Mesona (CEM) and reheated, the resulting gel showed higher values of modulus and tanδ at more than 35°C. The behavior of G' was similar to that of konjac mannan gel except a high value of tanδ. It is estimated that the behavior of G' was attributable to additional swelling of insufficiently pasted starch granules, but for tanδ some interaction with polysaccharide in CEM was responsible.
Conventional ηsp/C vs. C plots for dilute aqueous and 4M urea solutions of CEM were very strongly concave-upward. The intrinsic viscosity estimated by the method of Fuoss, where against was plotted, suggested a rather small molecular size.
A cryo-scanning electron microscope (SEM) was used to observe the structures of CEM-starch gel prepared at 10°C and the gel reheated at 50°C. Thin membrane was recognized in SEM images on the outside of extremely deformed swollen starch granules in these gels. The membrane in the gel at 50°C was thicker than that in the gel at 10°C. It is considered that the membrane was formed by some interaction between the polysaccharide in CEM and naked short chain on the surface of starch granules, and a network structure as framework of the gel formed by linkage of the membrane.
