Characterization of internal structure of maize starch without amylose and amylopectin separation.

Normal maize starch was used to characterize the internal structure of starch without separating amylose and amylopectin, and the result was compared with amylose-free waxy maize starch. The clusters in the whole starch were produced by partial hydrolysis using α-amylase of Bacillus amyloliquefaciens, and were subsequently treated with β-amylase to remove the linear amylose and to produce β-limit dextrins of clusters from amylopectin. The clusters were further hydrolyzed extensively with α-amylase to produce building blocks. The compositions of clusters in the form of β-limit dextrins and their building blocks were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography. The results showed that the structures of clusters and building blocks from whole starch of normal and waxy starches were similar. By number, each cluster contained 9-10 chains and 5-6 building blocks. The inter-block chain length in the clusters of whole starch was around six glucosyl residues. This study explored an alternate procedure to characterize the composition of branches in whole starch without separating amylose and amylopectin components.