2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Starch granule-associated proteins have been shown in our laboratory to reduce the breakdown of starch pastes and increase the solid behavior (storage modulus) of pastes. The objectives of this study were to determine locations of starch granule-associated proteins, and to reveal the existence or distribution of proteins in the pasted starch granule structures. Locations of proteins were shown using a protein specific dye with confocal laser scanning microscopy. The dye, 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde, fluoresces only after reaction with primary amines in proteins. With this technique, starch granule proteins were found concentrated in semi-crystalline regions in concentric spheres in potato, corn and wheat starches. In amylose-free potato starch and waxy maize starch, no protein rings were found. This implies that the internal protein spheres were granule-bound starch synthase (GBSS). The starch granule-associated proteins were also found tightly associated with and concentrated in the periphery of isolated normal potato and maize starch ghosts, while virtually no proteins were found in the isolated gelatinized amylose-free potato and waxy maize starch pastes. This study revealed the locations of GBSS in starch granules, and suggests that these are the same location as biosynthesis of amylose. The tight association of proteins with starch ghosts suggests a structural basis for the contribution of starch granule-proteins to paste rheology.