Lesson 2 - Cleaning Systems and Control
This lesson explores the concepts of hygienic design and the Cleaning-in-Place (CIP) systems in the brewery. We examine the nature of soils, the chemicals used to remove them and how we can validate cleaning effectiveness. We also consider the optimisation of modern cleaning systems within the brewery.
Point of Reflection - Reconvene
Welcome back. So, what were your thoughts?
In the world of brewery cleaning we need to make compromises and so adjust the relative weighting of the four factors. Why is this so? It’s because of production schedules putting pressure on cleaning time, unsuitability of some equipment to be cleaned at higher temperatures and chemical concentrations and incompatibility of certain environments with some of the cleaning agents used.
The most constrained factor in a modern brewery operation is time. We need to allocate dedicated time for cleaning, and in production constrained areas this will be less time than ideal, so where possible we will clean hotter, with more concentrated and effective chemicals and with higher mechanical action. An example would be wort main cleaning.
The hot side of the brewery, namely the brewhouse vessels, are also typically cleaned with hot caustic detergent. The cold fermentation, maturation and bright beer tank vessels are cleaned cold with a substitution of increased chemical and/or mechanical action.
In high CO2 areas such as maturation vessels caustic is unsuitable and risky to use due to possible vessel implosion, so a compromise is made by using acid. While effective in the short term, occasional caustic cleans with CO2 removed are essential to the long-term cleanliness of these vessels.
Certain areas in the brewery may not have been designed for cleaning, an example being the water supply mains. This can lead to biofilm build up requiring an out of the ordinary cleaning intervention such as a manual ‘fill and soak’ over a weekend of non-production. Here mechanical action and temperature would be substituted with time.
Terminology relating to cleaning
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Clean conditions – defined as those following the removal of all soils, but not all vegetative cells. Thus, the higher the required degree of cleanliness, the more robust the cleaning process has to be and the more important it becomes to ensure that the plant is designed for effective cleaning.
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Hygienic conditions – defined as a degree of cleanliness which has been achieved by elimination of vegetative forms of life, making it suitable for most aspects of beer brewing.
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Disinfection – more commonly referred to as sanitisation, may be defined as the destruction of microorganisms, but not usually bacterial spores. It does not necessarily kill all microorganisms but reduces them to a level acceptable for a defined purpose, i.e. a level which is harmful neither to health nor to the quality of perishable goods (in our case, beer).
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Sterilisation – defined as the elimination of all forms of life including, microbial spores. Typically, this is most effectively achieved with live (wet) steam at a minimum temperature of 122 °C for a contact time of at least 15 minutes, as occurs in a laboratory autoclave for preparing growth media. Certain parts of the brewery plant may have this capability, for example, the yeast propagator.