Synthesis and optimisation of the Wits Micro-Brewery Plant
Date
2011-04-20
Authors
Baloyi, Thabo Victor
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Abstract
The brewing industry is facing challenges on rising commodity prices and utility prices
that rise by a high margin on a yearly basis. Effective methods are required to reduce
other process variables which elevate the operational costs in the production of beer. The
aim of this study was to design and investigate the optimal control philosophy for beer
fermentation using the proportional integral derivative (PID) control algorithm in the
Micro-Brewery at the University of the Witwatersrand. This will be achieved by
controlling the cooling regimes of the fermenter jacket in order to compute the gain
constant (K1) that would minimise the dead time (Td) and process reaction time (Ti) and
produce a beer which will have desirable palatability attributes. All investigations were
performed using a Saccharomyces cerevisiae yeast strain and wort of 14.30P apparent
extract. The controller constant, the dead time and rise time were found to be 9.6 second
,2 seconds and 1second, respectively. The Isoamyl acetate, Ethyl acetate and Ethyl
Caproate esters were found to be 6.8, 25 and 9 ppm, respectively and the vicinal
diketones (VDK) level was found to 20 ppb at the end of the fermentation. This study
showed that beer colour (EBD) was found to improve with fermentation temperature for
the first 2 days then remain unchanged and showed that temperature is a possible process
variable in the optimisation of colour. The study also showed that the fermentation rate
and duration increase with increase in temperature. The flavour ratio (R) improves as the
temperature increases. The developed simulation program helped in selecting optimal
profiles to reduce dead time and improve the controller efficiency.