Development of a 96-well plate iodine binding assay for amylose content determination

Cereal starch amylose/amylopectin (AM/AP) is critical in functional properties for food and industrial applications. Conventional methods of AM/AP are time consuming and labor intensive making it difficult to screen the large sample sets necessary for evaluating breeding samples and investigating environmental impact on starch development. The objective was to adapt and optimize the iodine binding assay in a 96-well plate format for measurement at both λ 620 nm and λ 510 nm. The standard curve for amylose content was scaled to a 96-well plate format and demonstrated R2 values of 0.999 and 0.993 for single and dual wavelengths, respectively. The plate methods were applicable over large ranges of amylose contents: high amylose maize starch at 61.7 ± 2.3%, normal wheat starch at 29.0 ± 0.74%, and a waxy maize starch at 1.2 ± 0.9%. The method exhibited slightly greater amylose content values than the Concanavalin A method for normal type starches; but is consistent with cuvette scale iodine binding assays.