The physical properties of soft wheat starch granule surface proteins and soy flours or isolates, which contribute to the texture of sugar-snap cookies was studied. Soft wheat flour was deproteinated and cookies were produced containing 0, 10, 20 or 30% soy flour, or one of two types of ground, textured soy flour. Color, fracture force and spread ratio of cookies were determined. Cookies formulated with wheat starch stripped of the starch granule surface proteins exhibited significant alterations in diameter, fracture force, thickness and surface cracking. Cookies containing ground, textured soy flour and protein-stripped starch granule wheat flour were larger, thinner and had more surface cracking than those produced with nontextured soy flour. Wheat starch granule surface proteins appear to partially mediate the interaction of proteins and starch in a sugar-snap cookie system.