Identification of botanical origin of starches by SDS-PAGE analysis of starch granule-associated proteins

Starch granule-associated proteins (SGAPs) were extracted from various starches and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with silver staining. The SDS-PAGE results showed that granule-bound starch synthase (GBSS) of approximately 60 kDa was found in most starches, except waxy-type starches. Starches exhibited the presence of proteins specific to the botanical origin, including those of 22 kDa for maize; 160 and 98 kDa for potato; 140, 115, 90, and 80 kDa for wheat. These proteins could be detected from noodles prepared with the corresponding starches. The detection of the specific proteins by SDS-PAGE may be used to identify the origin of starch incorporated in various foods and industrial products.