John Carvell (1), BETTIE LODOLO (2), Martin Brookes (2), Clint Viljoen (2)
(1) Aber Instruments, Aberystwyth, U.K.; (2) SABMiller, South Africa
In order to produce consistent fermentation performance and beer
quality, it is essential that yeast stocks are managed in such a way
that variability in physiological condition is minimal. Providing that
this is accomplished and there is adequate control of other important
variables such as wort composition and oxygen concentration,
fermentation performance is governed in large part, by the yeast
pitching rate. It follows that procedures that lead to precise and
repeatable control of yeast pitching rate will result in consistent
fermentation performance. A yeast monitor (Aber Instruments Ltd., UK)
incorporated into an automatic yeast dosing system is the only current
workable means of consistently and accurately controlling pitching rate
in-line automatically. Breweries that have replaced manual laboratory
methods for measuring live yeast cell concentration with automatic
pitching rate systems based on a yeast monitor have benefited from much
more consistent fermentations. This might be reported as more consistent
fermentation rates and times or fewer corrective actions such as beer
blending. It follows that any improvements in the consistency of
fermentation will result in an improvement in quality of the final beer.
In this poster, we report the findings of using a yeast monitor at SAB
Ltd. in South Africa. RDF (real degree of fermentation) and ferment
rates before and after the installation of the yeast monitor were used
as a measure of the success of the installation.
Elizabeth Lodolo completed her B.S. degree in microbiology, genetics
and zoology at the University of Pretoria, and she started her career as
a bursar with the CSIR, where she completed her M.S. degree (with
distinction). Her studies then focused on yeast and fungal molecular
genetics expressing heterologous proteins in yeast and developing rapid
molecular tools. She moved to SAB as a microbiologist in 1992, where her
investigations focused on fermentation optimization. She received her
Ph.D. degree from the University of Stellenbosch for a study titled “The
Effects of Oxygen on the Fermentation Ability of S. cerevisiae
During High-Gravity Wort Fermentations” and the MBAA Presidential Award
for outstanding refereed paper based on this work. She worked as a
senior research scientist for SABMiller Global Research, investigating
various aspects of propagation optimization, yeast fingerprinting, roles
of yeast food (zinc and CO2 toxicity), yeast vitality, yeast
handling, flocculation, and microbiological control. She has authored
or coauthored 23 papers related to yeast research and brewing science
and served as a panel member for the National Research Foundation. She
is an affiliated professor at the University of the Free State and, in
2011, was invited to serve on the ASBC Journal Editorial Board.
Since 2007 she has been the SAB brewing consultant for yeast,
fermentation and hygiene in the SAB Ltd. Brewing Centre of Excellence.
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