The acidification power test and the behaviour of yeast in brewery fermentations.

Fernandez, S., Gonzalez, G. and Sierra, A.

Abstract
The "acidification power" test, in which the pH of a glucose solution in which yeast cells are suspended serves as an indicator of their physiological condition, was used in studies on the fermentation performance of yeast in the brewery. The effects of storing yeast slurries recovered from brewery fermentations for varying periods at different temperatures were investigated, the results of the acidification power test for each sample being compared with the time taken by the same yeast to reduce the gravity of a wort from 15 to 10 degrees Plato. The two tests were found to be closely correlated, longer and warmer storage leading to both a slower fermentation rate and a smaller change in pH. It was also found that differences in the degree of acidification achieved by different strains after storage under the same conditions corresponded to the differences in vicinal diketones reduction capability between the same strains.
Keywords : acidification brewers' yeast fermentation measurement performance pH storage temperature time