Lesson 4 - Wort Cooling and Oxygenation Technology
This lesson will firstly compare the design and operation of different wort cooling systems, and will give you enough information to help you describe why you would choose one wort cooling system over another. It will then move on to wort oxygenation systems, giving you enough information to help you make the same decision regarding this type of system.
Wort Cooling and Oxygenation Objectives
Let us first consider the main objectives of wort cooling and oxygenation. Overall, we are preparing the wort for our yeast to be pitched, so we can begin fermentation both consistently and reliably.
The previous stage of wort clarification was instrumental in preparing the clarity and stability of the wort. This made the wort ready for receiving yeast, avoiding coating it with trub particulate matter. It also worked to maintain the required specifications of the wort components. We now need to consider the additional fermentation inputs of temperature and oxygen, to be able to stabilise the yeast and prepare it for a consistent fermentation operation. This starts with growth, and for this our yeast needs attemperated food (wort) and oxygen.
The objectives of wort cooling and oxygenation are:
- Collect the required volume of wort
- Achieve target temperature
- Achieve target original gravity
- Achieve target oxygenation level
- Minimise time taken
- Minimise waste
- Minimise energy use
- Recover heat from wort
- Precipitate cold break
- Prevent infection
All these objectives are critical, as wort cooling and oxygenation is the interface between the brewhouse and fermentation departments. Although this is a man-made interface, it does represent a transition from hot to cold processing and the hygiene challenges that come with this transition. The cooling must be achieved as quickly as possible, not only to optimise cycle times, but also to stop or reduce the rates of all chemical reactions associated with wort boiling. It will also minimise the impacts of oxygen on the wort before yeast is pitched. As the wort cools, it becomes hazy (loss of clarity) as the cold break forms. The brewer can remove this cold break, or not, depending on brand requirements. Oxygen is then added for the yeast to use for growth. Most modern and large-scale breweries recapture the heat from the cooled wort.
The above objectives give us an idea of what we expect from our wort cooling process. Let us now explore the technology that can help us achieve these objectives.