The invention provides a method of preparing a stable enzyme-thinned starch dispersion characterized by a selected degree of thinning including the steps of: (a) combining a derivatized granular starch with an alpha-amylase enzyme to form a starch/enzyme slurry; (b) passing said starch/enzyme slurry through a jet cooker under conditions selected to gelatinize the starch; (c) treating the starch/enzyme slurry to complete gelatinization and achieve the selected degree of thinning such that the concentration of starch hydrolyzate product having a molecular weight greater than 1,000,000 daltons is 5 % or greater; and (d) deactivating the enzyme.