P-10
Fluorometric method for tracking fermentation rates in the brewery. Monitoring fermentations can provide brewers with important in-process
information. Such information is useful in order to maintain consistent and on
time fermentations. Traditional methods include specific gravity for the
measurement of alcohol production. Also, hemacytometers or particle counter
measurements are often used as supplemental tests for the determination of cell
concentration. While these methods provide some information about the growth of
yeast during fermentation, they are inaccurate and do not provide data about
yeast activity. What is needed is the ability to accurately measure the activity
of the yeast culture to predict and track the performance of fermentation. A
novel fluorometric technology for fermentation tracking is described. This
technology, the Easy Count, rapidly measures the metabolism of the yeast cells,
and can be used to monitor yeast activity through the course of fermentation. In
this study, several normal brewery fermentations were monitored using a Coulter
counter, hemacytometer counts, specific gravity and Easy Count. A correlation of
(R(^2)=0.89) was found between the Easy Count and Coulter count measurements. A
correlation of (R(^2)=0.94) was found between Easy Count and hemacytometer
measurements. The Easy Count also correlated well to specific gravity readings
(R(^2)=0.97). In addition, an overpitched and unsuccessful fermentation was
monitored using both the Easy Count and Coulter counter. In this case, the Easy
Count indicated a significant loss of activity while the Coulter counter
reported no dramatic changes in cell concentration. These results show that the
metabolic activity as measured by the Easy Count is a more useful measurement of
yeast performance than cell concentration. Thus, the Easy Count can be used by
breweries to provide critical information about the activity of yeast
in-process.
Darby McLean received her Bachelors degree in Microbiology with a minor in
Chemistry from Eastern Washington University. After graduation, she worked at
the Spokane Intercollegiate Research and Technology Institute on methods for
enumeration of bacteria in dairy products. She then moved to GenPrime, where she
was a co-inventor of the Easy Count technology. Darby has presented papers at
several scientific meetings, is a co-author on a patent and the author of two
papers in preparation on microbial counting technologies.
D. McLEAN (1), J. Holcomb (1), K. Maxwell (1), J. B. Somes (1), and J. E. Fleming
(2). (1) GenPrime Inc., 157 S. Howard Suite #605, Spokane, WA 99201, and (2)
Department of Biology, Eastern Washington University, Cheney, WA 99004.