EFFECT OF HEAT TREATMENT ON THE VISCOSITY OF GLUTEN DISPERSED IN ALKALI, ACID AND NEUTRAL SOLVENTS

Abstract

The viscosity of gluten dispersions in sodium hydroxide and acetic acid always decreased during heat treatment, the magnitude of the decrease being much larger in the former than in the latter solvent. Dispersions in urea solution decreased to a fixed viscosity level at temperatures below 70 °C., but at higher temperatures the initial viscosity decrease of dilute dispersions was followed by an increase, then again by a decrease. At 60 °C., dispersions in sodium salicylate increased in viscosity throughout the period of heat treatment, but at 80 °C. the viscosity increased to a maximum and then fell off. This qualitative difference in the viscosity changes at temperatures above and below 70 °C. in the neutral solvents, was the only evidence obtained to indicate that dispersed gluten undergoes any sudden change in character at a certain temperature, comparable to the so-called "coagulation point" of albumins. The results indicate that the changes occurring below 70 °C. can be attributed mainly to the action of the solvent on the protein.