Lesson 5 - Wort Cooling and Oxygenation Technology and Process Control SAQ
This lesson provides the opportunity for you to test yourself on the material covered in Lesson 4 (Wort Cooling and Oxygenation Technology and Process Control) and determine the level to which you have attained the expected outcomes.
Suggested Response - Q3
*Your ale brewery is switching to high gravity brewing. Explain the wort cooling and oxygenation requirements.
Response:
Ales typically have higher fermentation temperatures than lagers and are cooled and pitched at higher temperatures too. These temperatures are typically:
Ale wort collection: 15-22°C
Lager wort collection: 6-12°C
We therefore require less cooling loads for ales. Some smaller breweries can even use local municipal water at ambient temperatures of 12-15°C in order to attain the required cooling.
For the movement to high gravity brewing, we would primarily need to re-evaluate wort aeration. The higher the gravity, the higher the amount of oxygen needed. This is because the higher the gravity, the higher the pitching rate will be, and hence there is more yeast that requires oxygen. In addition to this, the solubility of oxygen decreases as the gravity of the wort increases. We thus have to add more oxygen to achieve the desired amount of dissolved oxygen in the wort.
Furthermore, at high gravities, we need to use pure oxygen to achieve the higher requirements of dissolved oxygen in the wort. This can replace the use of sterile air or can be used in combination.
Brewing at high gravity means that we can also use dilution water before, during or after wort has been cooled into the fermenter. The cooling requirements will thus also change. This is because the volume of liquid to be cooled will alter depending on the addition point of the dilution water. If we use dilution water dosed in before the wort cooler, the wort cooler will need to be bigger. This will accommodate the extra volume and ensure that we do not extend cooling times.