A simplified method of determining the internal structure of amylopectin from barley starch without amylopectin isolation

To determine the internal structure of barley starch without amylopectin isolation, whole starch was hydrolyzed using beta-amylase to remove the linear amylose and obtain beta-limit dextrins (beta-LDs). The beta-LDs were treated with extensive a-amylase to prepare alpha-limit dextrins (alpha-LDs), and the alpha-LDs were further hydrolyzed with beta-amylase into building blocks. The chain-length distribution of beta-LD and building block composition were analyzed by sizeexclusion chromatography and anion-exchange chromatography. The internal structure of the barley whole starches had similar pattern to barley amylopectins analyzed by conventional methods. The starch of barley amol-mutated varieties contained more short internal B-chains and less long internal B-chains than that of other varieties. The starch from amol-mutated varieties had more large building blocks than that from waxy varieties. The simplified method presented in this study can effectively characterize starch internal structure that relates to physicochemical properties of starch, although some details of amylopectin structure are not assessable