Lesson 10 - Maturation and Finishing End of Unit SAQ
You have now completed the Maturation and Finishing Unit. This lesson enables you to test yourself on the material covered and to determine the level to which you have met the learning outcomes. It will provide you the opportunity to test your knowledge with a last set of self-assessment questions.
Suggested Response - Q1
*** The filtration department in a brewery is consistently finding high dissolved oxygen levels at the inlet to the filter. You, as the technical brewer, have been tasked to root cause the issue. List the potential sources and how they may have occurred.
Response:
At the end of fermentation, oxygen levels will be negligible as it has been fully metabolised by the yeast. Elevated oxygen levels may occur due to transfer from the fermentation tank and downstream to the filter, in numerous places. Sources of dissolved oxygen may originate from:
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The inadequate flushing of lines with deaerated water before introducing beer into the system: deaerated water removes any oxygen in lines before coming into contact with the beer to avoid oxidation. If this process does not happen or is inadequate, oxygen will dissolve into the beer and cause elevated DO (dissolved oxygen) levels.
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An inadequate CO2 blanket in receiving vessels: similarly to flushing lines adequately, oxygen must be dispelled by CO2 before beer is filled into the tank, otherwise the beer will pick-up DO upon filling.
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An incorrectly functioning centrifuge, which is normally placed between a fermentation vessel and a maturation vessel in a dual-tank system: there should always be a CO2 purge facility to prevent oxygen pick-up but if this facility is not functioning correctly, it increases the risk of DO pick up.
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The inadequate flushing of vessels and lines if an extraction tank is used for dry-hopping or accelerated wood ageing: the vessels and lines must be flushed with CO2 beforehand otherwise it will lead to high DOs.
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The incorrect use of filter powder, particularly as a key design feature of a filter powder make-up system is to ensure the filter powder slurry is purged with CO2 to remove any oxygen trapped in the voids of the powder.
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Continuous agitation of the slurry helps create homogeneity and displaces trapped oxygen: if the filter powder is used too soon after make-up or the CO2 supply flow is inadequate, the CO2 may not fully displace DO, which would cause high oxygen reading on to the filter inlet.