Some properties of branched and linear dextrins from Nägeli amylodextrin

Abstract

Branched dextrin (BD) and linear dextrin (LD) were prepared from Nägeli amylodextrin, and their molecular structure and some properties (the interaction with 2- p-toluidinylnaphthalene-6-sulfonate (TNS) in solution and the aggregation into precipitate) were investigated. BD and LD were singly branched dextrin ( d. p. = 25.7) with the branched point near the reducing end, and practically linear dextrin ( d. p. = 12.4), respectively. The fluorescence intensity of TNS increased with increasing concentrations of α-cyclodextrin, BD and LD, indicating their interactions with each other, in which the values of the dissociation constant were estimated to be 20mM, 3.4mM and 7.8 mM, respectively. In aqueous 16 M methanol, the aggregation of BD was much faster than that of LD, and both dextrins were precipitated into a type A crystallite. It is considered that the branch point in the BD which is a connection of two linear dextrins may trigger the association of the unit chains. On the other hand, the aggregation of dextrins was retarded in the presence of lauric acid. These results may be applicable to the local phenomenon of the whole amylopectin.