Process improvements at the Ibhayi brewery, South Africa, from using a yeast monitor

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.