Titrimetric Measurement of Fermentation

Abstract

The fact that yeast in high concentration ferments glucose very rapidly has been put to considerable use in the analysis of blood and other biochemical material. The fermentation can be so regulated that small quantities of glucose are completely broken down in a few minutes at room temperatures. The evolution of CO2 takes place so rapidly that the red color of phenol red (indicator) in a weakly alkaline glucose-yeast mixture turns to yellow in a few seconds.In an attempt to apply this phenomenon as a means of quantitative observations in the study of fermentation processes, several serviceable procedures were tried out. The one to be described promises usefulness as the basis of a rather simple analytical technique.The reagents employed are: (a) 0.01 molecular sodium carbonate solution, (b) 0.06% aqueous solution of phenol red, and (c) a 20% yeast suspension prepared by rubbing up 20 g. of commercial baker's yeast in water and making up the volume to 100 cc.The procedure is as follows: Measure into a tes...