ON-LINE MONITORING OF BREWERY FERMENTATION BY MEASUREMENT OF CO₂EVOLUTION RATE

Abstract

To take full advantage of computer monitoring and control systems already in existence in many breweries, there is a need for reliable and inexpensive on-line sensors. Prior to the development of any system for production scale conditions, the underlying principles of the method of measurement adopted have to be investigated.Work at the laboratory (1.5 Litre and 11 Litre), pilot (30 Litre) and experimental brewery (100 hi) scales of fermentation has demonstrated that a good correlation exists between evolved CO2 and changes in specific gravity. During the period from the onset of CO2 evolution to the end of a fermentation, it was found that evolved CO2 yield was ca. 1.0 gCO2/ Litre/degree gravity drop. Metering systems based on evolved CO2 determination are nonintrusive, simple to install and cost effective.

Calculation of pressure growth during fermentation in a closed container.

“…V provozu se nejčastěji využívalo měření průtoku unikajícího oxidu uhličitého (Eyben, 1989;Daoud a Searle, 1990). Při kvašení vzniká relativně velké množství tohoto plynu, jehož měření na výstupu z tanku je snadné, přičemž se používá různých principů (Venturiho trubice, ochlazování termočlánku, ultrazvuk) (Kobayashi a Hiroshima, 2005).…”

“…The most commonly way how to follow the industrial fermentation is the measurement of the flow rate carbon dioxide leaving fermentation vessel (Eyben, 1989;Daoud and Searle, 1990). When large amount of gas is formed the measurement is easy using various principles (Venturi tube, thermocouple flowmeter, ultrasound) (Kobayashi and Hiroshima, 2005).…”

4 Developments in Brewery Fermentation

“…It may be measured by diverting part of the exhaust gas from the fermenting vessel via a thermal mass flow meter (Stassi et aI., 1987;Eyben, 1989;Daoud and Searle, 1990). This is an attractive method for monitoring fermentation since it uses tried and tested technology which is totally non-invasive.…”

“…Suggested parameters for monitoring are the rate of carbon dioxide evolution (Stassi et al, 1987;Daoud and Searle, 1990), decline in specific gravity (Armstrong, 1986), decline in pH (Leedham, 1983) and by ultrasonic detection (Forrest, 1986).…”

On-Line Estimation and Control of Apparent Extract Concentration in Low-Malt Beer Fermentation

“…In the fermentation process, the main sugars in a low amino nitrogen wort, i.e., glucose, maltose, and maltotriose, are converted to alcohol, carbon dioxide and the volatile compounds responsible for determining flavour 8,11,12,15,16,20,21 . At present, operators in factories take samples every day to determine the state of the fermentation and to check the progress of fermentation despite the presence of many fermentation models 4,7,8,13 . There are previous reports on the development of an estimation method for the sugar concentration in the beer brewing process by measuring the CO 2 production rate 18,19 and maximizing the alcohol concentration in minimum time 1,9 , but, there are no previous papers concerned with the online estimation of cell activity and a feed-back control of apparent extract concentration.…”