O-18
A rapid, automatic method for determining total and viable cell
concentrations in pitching yeast slurries - A comparison with conventional
brewery methods. Precise determination of the total and viable cell concentration in pitching
yeast slurry is vital for the assessment of yeast quality and for accurate
control of pitching rate. However, traditional methods can be slow,
labour-intensive and require skilled operators. A novel instrument, the Yeast Viability
Analyser, is described in which these analyses can be made rapidly and
automatically using a small, undiluted sample of pitching yeast slurry, thus
removing a significant source of operator error. This instrument employs a
combination of radio-frequency impedance, to measure the viable cell
concentration, with a bulk fluorescence measurement, using a membrane potential
dye, which allows for determination of the dead cell count. From these two
results, the percentage viability is computed automatically. Results are
presented, from slurry samples taken from a production brewery, which compare
the yeast viability measurements obtained using the Yeast Viability Analyser
with those derived from a number of conventional methods.
Kirsty Turner graduated from the University of Leeds with a B.Sc. in
microbiology. In 1994 she commenced her Ph.D. at the University of Liverpool,
studying the effects of environmental stresses on Salmonella typhimurium.
Since joining Aber Instruments in 2000 she has worked on developing novel
methods for determining cell viability.
KIRSTY TURNER, Robert Todd, and John Carvell. Aber Instruments Ltd.,
Aberystwyth, Ceredigion, SY23 3AH, UK.