Alkali Gelatinization of Starches

Grain starches, chemically or genetically modified grain starches, tuber starches, and some from other botanical sources were treated at room temperature in media containing a constant amount of water and sodiumhydroxide. Appearances and viscosities of the mixtures were noted during a 7‐day quiescent period. The point of complete gelatinization of the starch was deducible from the viscosity changes, as well as from visual observations. Although there were some noticeable differences between the starches, an NaOH to starch ratio of 3.5 to 3.8 meq/g should assure complete gelatinization within several hours or less. This alkali: starch ratio is compared to previous ratios expressed in the literature. A slight dependency of the ratio upon the starch concentration is indicated. The birefringence endpoint temperature ranges of the starches were determined, and other implications from the experiments with the 21 materials are discussed.