THE ALTERATION OF THE FLOW CHARACTERISTICS AND TEXTURE OF STARCH PASTES

Abstract

Starch pastes are classified according to the "length" of the flow or texture, and the practical importance of this characteristic in commercial applications for starch pastes is noted, e.g. for culinary uses. The differences in flow and texture may be attributed to the differences in phase-volume relations and the deformability of the swollen granules in the paste. It is shown that heating in water below the gelatinization point reduces both the volume occupied per unit concentration by the dispersed phase, and also increases the rigidity of the swollen granules. The viscosity of the paste is greatly reduced and the critical concentration of the starches is correspondingly increased by this treatment. The effect is particularly large in the case of potato starch, but is appreciable also with corn and wheat starches. Suspension of starches in dilute sulphurous acid (0.25% SO₂) effects a similar change in somewhat greater degree, hence it is probable that the flow characteristics of corn starch are altered during the process of extraction. The practical application of these modifications is briefly discussed.