Studies on the so-called protein turbidity of saké(V)

On the influence of heating conditions, pH, and metals added.

Abstract

The turbidity of sake depended on heating conditions, but no common effect was observed with all kinds of saké.
When the pH of sake was adjusted before heating, the turbidity decreased with decrease of pH below 4.8.5.0. The turbidity increared when its pH value was increased to the original value after heating. This phenomenon seemed to be related with isoeletric points of turbid materials.
The ash of turbid materials in sake contained metals such as Ca, Cu, Mg, Fe, etc.
As a preliminary experiment concerning the relation between the turbidity and added metals, the Koji solutions with added Metals were fermented. The turbidity of the filtrates after heating was likely to be influenced by added metals, i.e., Ca, Mn, Fe, Cu, etc., and the filtrates in case of no added metals were more tubid than those in case of added metals, This seemed to indicate that fermentation conditions had some inflcunces upon turbidity.